| QUESTION NO. P1215-4: Sharp CTV Model CX2073 - set dead, no sop. Any clues on possible fault? |
| Change IC701 in this case there was low ohms between pins 6 -7 and 6-8. If the set is compleatly dead with a blown fuse check pins 10 -15 and 10 - 11. Also change C740 1uF 400V, C713 47uF 25V and C711 4.7uF 63V. Change ZD701 4.6V 1W? zener and ZD702 3.6V 1W? zener Also check Q701 2SC2236 and varistor VD701 RH-VX0010CEZZ. |
| QUESTION NO. P114-6: Mitsubishi model CS-2715R TV, tries to start when the set is turned on, the relay clicks on then off. The degaussing coil comes on and seems to stay on too long. If the set is turned on manually (not by remote), the operator gets zapped. When the relay was bypassed bright light came from the CRT yoke and the HOT blew. |
| Flyback, Yoke, and/or CRT. Flashes from yoke denote either a shorted yoke or a punctured crt neck. Short is what killed the hot, may have also damaged fbt. Check regulated b+ also, must be going way high to cause this type of damage. |
| QUESTION NO. P114-2: Sony KV27V55. The screen has shifted downwards slowly. It started small, now it is about an inch wide. Cannot see any visible signs and no diagrams either. |
| Direct view Sony with one color shifting? Sounds as if the static convergence magnets, on the crt neck, have been mis-adjusted. The purity, and convergence adjustments are done with the three concentric rings behind the yoke assembly. Spot areas are adjusted using 'spot' and 'wand' type magnetic material and yoke wedges. Shifting of a particular color, without affecting the others, may be a problem within the crt itself. |
| QUESTION NO. P113-4: 13" RCA X13152GS that blows the horizontal output transistor every couple of months. All supplies etc, seem ok. |
| Check fbt, connections @ pcd, intermittant shorts in crt, or possible breakdown of damper diodes, caps, or other devices in derived supplies. Also confirm input voltage is not developing surges that may trigger problem. |
| QUESTION NO. P113-2: Sony 15sx-trinitron powers up, tube lights, no video, no visible component failure. |
| Check for ring cracks @ the on board regulator ics. Also for a load on one of the smps feeds to the tuner, video, audio cks. |
| QUESTION NO. P113-2: Sony 15sx-trinitron powers up, tube lights, no video, no visible component failure. |
| Check for ring cracks @ the on board regulator ics. Also for a load on one of the smps feeds to the tuner, video, audio cks. |
| QUESTION NO. P113-5: Mitsubishi model CS-2715R TV, the HOT (Q532)is marked D1879. What is the real part number of this device? Is there a replacement part? |
| That transistor is a Sanyo 2SD1879, a widely-available type. If that is all you need, Mouser (800-346-6873) has it for $2.85 (cat#620-2SD1879), and they do not have a minimum order requirement, unlike some others. |
| 2SD1879 Good Part # may have a flyback problem, common. Put component into circuit, run for 10 -20 minutes and check if flyback & part are unusually warm to touch. |
| QUESTION NO. P18-7: Sony 35xbr48 with a light shadow arc in the upper right. The arc is only visable on white, light blue yellow solids and from all sources. Degauss done, no effect. Adjusted picture and electronic focus, no effect. |
| Make absolutely sure there are no magnetic items, speakers, large power amplifiers, etc. near the tele. Have the degauss circuitry checked. Have the set manually degaused, have a signal generator connected to adjust the purity and check tracking low to high light conditions. Some of these adjustments may require the set being serviced by a qualified repair person. Make sure the person adjusting the set has the available time to confirm the problem and competently adjust set to factory specifications. |
| QUESTION NO. P1229-5: Could you tell me where I can get color chips for a Mitsubishi CS2671R color TV? They stopped making the chips in 1993. |
| Try Prelco Electronics in NJ (908-851-8600). They have a large selection of new and older TV, Stereo IC's and VCR semiconductors at low prices. |
| QUESTION NO. P1230-8: JVC model av2672s. The reception and sound are fine, problem is the picture is constantly changing from a good picture to a horizontal line in the center of the screen. |
| Check for poor solder connections at the vertical output devices and supplies to that circuit; also may be output ic failure. |
| QUESTION NO. P1230-5: 27" GE TV model 27CT613FE2 chassis number CTC177BH2. The problem is the picture shifts from being stretched to drooping in about 2 -3 inches, turning the power off and back on would sometimes correct this. I also get a bad pincushion while it is on. It does this even while view a tape. Is there any type of service mode menu to adjust pincushion? |
| Change the pin diode and associated capacitor. While you are at it, do the resoldering at the tuner and mpu ground reference points. Pin problem common on these chassis, seems cap fails and damages diode.#164589 & 200149. |
| QUESTION NO. P1216-9: Zenith model SE5749W powers up fine, but at random (not consistant) HV shuts down, crt filaments go out. It does not sound like horiz. osc. is working either, sound ok. Turn off and on, set comes right back on again, and works for awhile. |
| Good possibility the protect is being triggered by some effect, be it an internal arc in the in-famous Zenith crts, or a glitch in the power regulation on the smps/ deflection circuits. |
| QUESTION NO. P1216-7: RCA TV ctc185aa. I accidentally blew out u4103 and would like to know the replacemnet for it. The TV does not come on even though I am getting voltage going into the set. The relay does not click. |
| Good possibility you also have problems in the chopper and horiz output circuits. You will find with the 185 and similar chassis that the failure of the horz out usually damages the chopper and vice versa. EST had a very good article on this particular problem in their Oct issue, also Thompsom has a good technicial trouble shooting procedures for these chassis. |
| QUESTION NO. P1223-6: Sony TV model # KV-9PT40. IC 202 is intermittant when cooled and heated. I have no service data but the IC appears to be an 9v reg. I cannot find a cross or source. The part is labeled AN78M09R. It is a 4 pin IC not to be confused with a 78M09 which is 3. Anyone have a cross, source, or data sheet? |
| Sorry, you will have to order the part from Sony. Their engineers are some of the best in the world of electronics, however, they do like to design some propreitry parts too. |
| QUESTION NO. P121-7: 25" RCA TV with chassis 177. Replaced the output transistor and now have a clicking in the system it sounds like it is coming from the high voltage transformer. With the transistor replaced, would this let the transformer so that it is shorted out by arcing inside? The set sounds like it wants to come on but instead it just has the clicking noise. |
| Replace the flyback. |
| QUESTION NO. P1210-10: Hitachi projection tv (model 50fx30b, chassic ap62) that intermittently cuts off, the power light on the front goes dim, but does not go off. Turn the set off, and it will come back on ok. Takes three hours for the problem to show up, then about 30 minutes to do it again. |
| May have microprocessor related problems similar to the AP73 chassis. The repair on those are to replace the memory ic and reprogramm it. Contact Hitachi tech services to confirm if this is their recommended fix for your symptom. Also, check the power supply for proper operation and the hv protect circuits. |
| QUESTION NO. P1210-1: Pioneer sdp 4565k 45" set that has two small spots that show in the picture. Closer analysis confirms two holes in middle of red and green CRTS. These are not bacteria, but acutal holes in CRTs underneath fluid. May have been cause by electrical surge. Are these CRTs shot? |
| Phospher burns caused by some type of deflection failure. Contact Pioneer regarding the deflection problem and check the third crt. There may be the necessity to replace the power supply/deflection assembly to not have this happen again. Check the cost of the components before going too far with this set. |
| QUESTION NO. P124-3: Sony KV-27TS31 TV. It had intermittent sound and now the sound is almost gone. You can hear some distorted sound at highest volume setting. Both stereo channels are bad so I do not suspect anything past the AUDIO controller (IC431). Also, all voltages on the IC431 seem ok. I have tried to plug an audio amp into the audio outputs and they are also bad. When I turn mute on, all sound goes off completely. Trying to trace back, I am stuck here. |
| The audio problem with KV-27TS31 is due to an audio module (SBX-1643-11). |
| Replace Sony #8-746-371-20 with generic # BX1637-11, located on one of the vertical mounted sub modules with RCA input jacks. |
| QUESTION NO. P1110-3: Have a Sony 27" TV (KV2781R) that turns on after 10 minutes of hearing a click sound. When it does turn on, the picture is slighty pulled vertically inward from the right hand side. Everything goes back to normal once the TV warms up. The relay clicks on but I suspect the flyback transformer or the horizontal transistor. |
| Sounds as if you have a regulation problem, definetely not FBT. Look for a bad electrolytic cap in and around the regulator. |
| QUESTION NO. P121-3: Magnavox RX4035-04 13" TV. The set comes on for a split second and then goes off. If I push the power switch a few times, the set will stay on. But when I connect an antenna to the 75 ohm connector, the set goes off. |
| Replace str30130. |
| QUESTION NO. P123-9: RCA with chassis 177AM2. It has what appears to be a tuner problem. While turned on, it will go like the cable was unhooked. Turning the set off then back on most of the time takes care of the problem. I have soldered the grounds on the covers for the tuner which is soldered to the board. Sometimes it will go for days before it acts up. |
| There are at least 10 internal ground connections inside of the physical tuner assembly that must be repaired. Also, the ground reference points surrounding the MPU IC must be repaired. RCA has a nice template showing the specific pins within the tuner that require service. This is a very delicate area to be working in, if the attempt is botched, damage to the e-prom and/or delicate smd devices will occur. |
| QUESTION NO. P1113-2: Working on a Sansui TV/VCR Combo unit (AC/DC Model) Model# COM0953 made by Emerson, I believe. Picture is squashed in middle (looks like its in the "Wide Screen Format" as seen on LD Players, etc). Have replaced ALL electrolytic caps on "V OUT" section of PCB. Also, D402 (using ECG519 cross). Still nothing. Possibly the IC(s) next. I need part numbers or something to get a replacement. |
| Your Sansui combo unit was made by Orion. Vertical IC402,LA7840, manufacture part #103SD78400 can be purchased from Fox 1-800-321-6993. Check pin voltages.1-0v,2-10v,3-0v,4-3.6v,5-3.6v,6-25.7v,7-1.4v all dc. Wave form for vertical input pin5 should be 500mv 5ms div. on scope. |
| QUESTION NO. P1123-10: Zenith model SL2784BT 27" TV draws a current when power button is pushed and degauss activates but, no picture and no sound. |
| Zenith 'L' & 'M' Line sets have been known to have problems in the crt that can destroy the hv generating & occasionally the regulating circuits in the set. Confirm the crt is not exhibiting intermittant shorts internally before trying another known good module or you are just wasting your time. Probaby the regulator circuit or horizontal deflection circuits have been damaged. |
| QUESTION NO. P1117-7: Symphonic TVCR13B1 is dead. So far it looks like something in the power supply. I have good voltages up past the bridge but after that none. It seems like the switching supply is not working. I have no voltage at the on/off switch which appears to come from the flyback. |
| Look for bad caps in secondary side of switch mode power supply. Caps may test good or border line, replace anyway. Usually caused by two caps but replacing them all eliminates guess work. |
| QUESTION NO. P1119-1: Quasar model cktk2790s, chass#Aedp152. Found the following parts bad; horizontal output transistor, stk regulator, 5 watt 4.7 ohm resistor in power supply bad. Replaced above parts and also flyback transformer. Set comes on now but horizontal output gets hot, picture pull in on right side, shortly after blows all the above parts. |
| The fault you described could be that the HOT is not saturating due to lack of base drive. The HOT is usually driven via a pulse transformer. The base drive signal to the HOT should be a good pulse with fast rise and fall times. If not, there usually is a capacitor on the primary of the pulse transformer. Check that it is not bad. |
| QUESTION NO. P1120-6: I have a Mitsubishi VS-5073 PTV. This unit will not display picture nor sound. The tuner does work properly. The TV does not recognize an auxillary input. I have changed the switching ic. |
| If your specific unit has a standup PIP module having many surface mount electrolytic capacitors that may be your problem. If you can press the menu button and view a stable menu but not view the video then this may be a prime suspect. The PIP boards are still available from MGA |
| QUESTION NO. P1120-2: Sony TV KV-20S20, no sound, audio output IC is muted. Pin 46 of system control IC is high, supposed to be low to work. I wonder if the problem is with the system control IC or EEPROM IC? |
| Isolate the pin from the buss to allow the buss to go low. If the line does not go low when the IC pin is disconnected, you know the problem is from another source. If the sound returns [ buss goes low] when removing the MPU pin form the buss, the problem most likely is in the MPU. |
| QUESTION NO. P1112-5: Emerson 30, Model #TS 3050D. Repeated failure of D512 (shorting) in power supply. Replaced with ECG 570, lasts about 15 minutes. Happened twice. Have no schematic. Vertical linearity also incorrect (no adjustment provided), in case this has a bearing on the problem. |
| I replaced in Russian equipments,at repairs,the KP 303x (where x means anything) with BF 245 A,B,C in fuction of necessary Idss; KT368BM NPN,EBC,Vceo=15V,Ic=30mA,P=225 mW,Ft=900 MHz; KT940VNPN,ECB,Vceo=160V,Ic=0,1 A,hfe >= 25,P=1,2 W(10W*), Ft >= 90MHz. |
| QUESTION NO. P1112-1: Have a Sylvania RLF308; chassis NC3.5 with a burnt R403 in degaussing circuit and a scr 401 with no markings. Anyone know the values? |
| MCM (800-543-4330) lists thermistor R403 and thyristor SCR401 as Philips/Magnavox parts # 483511637005 and 483513027002. |
| QUESTION NO. P1110-8: I recieved a Sony TV Model# 1981R, which has a vertical foldover problem and also looses picture periodically. I have checked all the electrolytics in the vertical section and they measure fine. I did discover that when I tried to adjust the vertical bias control, by just touching it the picture goes to raster, and if I work it alittle it comes back. The part is RV505 Vertical bias control 33K mfg part no. 1-230-632-11. I tested the electrolytics in the vertical section, and they seem fine. I did find that when I tried adjusting the Vertical Bias Control the picture would come back and if I touched it again It would go out. My question is does this seem like a potential problem component, and if so does anyone know where I might get a 33K Trim Pot part# 1-230-632-11 or has anyone come accros this type of problem before on a Sony ? |
| It is possible that you have numerous poor solder connections in the area of the control you are physically adjusting. Also, non-linear sweep suggests defective active or passive components in the vertical sweep circuits. |
| QUESTION NO. P1112-3: I have a Sony TV KV-X2962U that has a line (made up of one scanline each of R, G and B) running right across the top of the screen. As it appears just above the picture it can be shifted up off the screen using the service mode but in 169 it's very obvious and intrusive. |
| Possibly what you are seeing is the VITS signals that are broadcast during the vertical blanking period. Adjust the vertical size to a point where the lines and vits are no longer available for viewing. |
| QUESTION NO. P1113-1: Mitsubishi big screen VS-466R does not turn on right away. It use to be a three minute wait, later became 10 minutes, now much longer. Also, it shuts off once in a while on its own. |
| Maybe the fact the crts are needing a longer time to exhibit a usable raster. More likely, there are problems in the power supply and deflection ckts. |
| QUESTION NO. P1023-9: Sony 27" Color Receiver Model KV27S35, Chassis No. SCCJ71G-A. This unit has high voltage (22KV), filament to CRT, audio is fine; but no raster. |
| Concentrate on IC351. It has been known for strange problems. |
| QUESTION NO. P115-6: I have an RCA model #gxr659pr has a 130 chasiss. Replaced hoizontal output transister and when the set is turned on there is a clicking sound set does not come but the clicking sound there. I have checked different components, they all seem fine. |
| In some cases C5007 in 26v line shorts..r402 and r404 open also. |
| QUESTION NO. P112-4: Mag 27" TV model 27TSC62110. Vertical is short at top and bottom. Replaced LA7338 VERT I.C, R539 was open. Vertical still short, no bulging, or overheated filter caps visible. |
| Jump filters with a smaller value when set is off. turn set on for reactions. |
| QUESTION NO. P116-7: Have an RCA model#vr335, the capstans do not move. |
| R243 opens and can cause this. |
| QUESTION NO. P1110-9: Goldstar CMT2108a TV. Having problems with the vertical deflection circuitry, white line in center of screen. Replaced the verical. out IC twice, works for awhile then collapses again. |
| Check filter cap off supply line. |
| QUESTION NO. P112-10: Sansui TV/VCR Combo Unit AC/DC Type Model COM0530 (I think) 13" TV VCR Below. Has a black bar across the top and bottom of screen, looks like its in the "Wide Screen Format". No menu function to change. I cannot locate a vertical or horizontal knob to adjust. |
| Found the fix for that combo! Hold Volume button down until it reads "0" on screen. Then hit "9" on remote control. This puts you into the "Service Menu". From there, you can adjust the vertical height, horizontal, etc. Works Great! No parts needed after-all! |
| QUESTION NO. P1110-5: I have a Zenith model numer SL2784BT. It appears to have a shut-down problem. When the power is turned on, it quickly shuts off again. I think the hv is working because a charge seems to build in the picture tube sometimes. It will not come on long enough to light the pictures tube however. Sams does not have a schematic for this set. |
| Consider a new CRT and circuit module. Common problem in the L line Zeniths is to have the crt fail and destroy the pcb. |
| QUESTION NO. P115-3: Working on a TV/VCR Combo unit, Sansui AC/DC Model# COM0953 made by Emerson, I believe. All functions work great. BUT, screen looks like its in the "Wide Screen Format". Black Bars on top and bottom of screen. Picture in the middle. Must be a "vertical" problem. No adjustment knobs for vertical. So far have done the following: Jumped 7 Caps on "V OUT" section of PCB. Replaced D402 with ECG519. There is one more cap I can jump. Other than that, im stuck. Unit stays the same. |
| Hold Volume Button Until it hits "0", then press "9" on Remote Control. This puts the unit into the "Service Mode". Once there, you can adjust the vertical height, horizontal, etc. I found this after I jumped ALL electrolytics, replaced a diode, and ordered a vertical IC(LA7840). Uug! Unit now works great! |
| QUESTION NO. P1023-8: Have 'burnt' unidentifiable component on Philips TV, Chassis AA27c601 (592268-1), Model - PG7290 BK01 Component # R400. Please supply specs for this component, it seems like the only thing wrong...so far. |
| NAP is located in Greenville, Tenn. USA It may be worth your while to contact them regarding schematic diagrams for your device. Also, having a burnt or open resistor, or other component, is indicative of other problems. You may need to dig much deeper to completely repair this item. |
| QUESTION NO. P1029-10: How can I get into the service mode on a Toshiba TP50H60? |
| Try mute mute menu. Press mute on remote, press it again, thern press menu button on front of receiver. |
| QUESTION NO. P116-3: How do you perform the digital convergence on a CTC177AH chassis? My convergence is a little off on this set that I am working on and I do not know how to do it since it does not have the normal convergence adjustments on the neck of the tube. |
| Buy another CRT from RCA! They come pre-converged with the nice little magnetic ring around the neck of the crt. With the "bonded Yoke". Sometimes you can play with the magnetic ring and ger the adjustments a bit closer but it is a real pain. |
| QUESTION NO. P113-5: Toshiba TV model CX21349. The problem is that everything is red. The green and blue drive on the crt board look fine on a scope, but only the red gun appears to be working. |
| I must tell you what you probably do not want to hear. Your CRT has gone. From experience,Toshiba crt's do not take too many insults [nor assaults]. |
| Using a white screen as input, if all drive levels are equal on the scope. It is a good chance your CRT is bad. |
| QUESTION NO. P113-1: I have a Mitsubishi VS-6061 big screen TV, and I need to access the service menu to make some adjustments. How do I get in? |
| To get into the servise menu, push menu then 2,3,5,9 -- be careful. |
| QUESTION NO. P105-8: I have a Symphonic 19" TV/VCR combo that is dead. When you apply power, you hear a relay click but nothing will power up. Awaiting schematics on it but looking for advice in the meantime. |
| These Funai/Symphonic units use a garden variety switching power supply. A way to cheat and fix them easily is to measure the AC voltage across all the electrolytic caps in the power supply, and replace the one or ones that show more than a few millivolts. Typically, however, the input filter to the bridge rectifier that is directly connected to the AC line shows a higher AC value across it than most, but this is normal. This cap usually is not the culprit. What happens is the capacitors lose some of their value and hence their ability to bypass AC. The smaller they get, the more AC you can read across them. 100mv might be ok, but .5 or more volts may indicate a problem. Never connect a cap with the supply energized. Always turn it off and solder a test cap across the suspect cap. If the problem goes away, bingo. Use only 105 degreee caps for best service. Other tricks involve a variac on the input (with an isoformer of course) and testing the cold side regulator circuit by applying a voltage to the output of the supply with it deenergized, but these are usualy not needed. Most of these can be found with the AC voltage measurement technique across the 'lytics! |
| QUESTION NO. P112-3: I am working on a Sony KV 2764 FE TV. A few minutes after powering up, the image and sound disappear. Only the video input allows to have an image and sound. I have checked the AGC and the memory, OK. I tried the cold spray and hot air but no effect. Where can I search the problem? |
| I see most Sony TV's fail due to bad grounds in either the tuner or the IF module, that little subassembly next to the tuner. Usually, but not always, rapping either will resolve which one has the trouble. I usually repair both and charge the customer accordingly to avoid a callback. You will need magnification and suitable solder tools for SMD technology. |
| Ckeck the IF pack For audio and video out. You probally should pull it and resolder it. They are known for bad conections. |
| QUESTION NO. P1020-5: JVC AV-27CM4 TV. Tuner will go directly to any channel keyed-in. However, in channel up/down mode, it skips over many channels in antenna and cable modes. Example: skips from channel 19-22 or just channel 30. It does not matter if cable is connected or not. Is this a tuner problem or processor? |
| It sounds like a programing problem. First, program all channels into memory. If the problem continues, you have a bad processor. |
| QUESTION NO. P113-9: How do you perform the convergence adjustment on a CTC 177AH chassis? I assume since the normal adjustments are not on the neck of the tv that it is a digital adjustment. |
| This set does not have digital alignment of beam alignment. What you need to do is order an adjustable beam bender assembly from RCA. It replaces the computer aligned magnetic strip that is taped to the yoke now. |
| Convergence is not adjustable on the CTC175/6/7 or for that matter most Thomson heaps from about 1986 to the present. The convergence is adjusted at the factory and usually is not adjustable afterward. The service literature mentions a "beam bender" and convergence adjustments, but I have never seen a unit with them. I doubt if you could change to this configuration. You might call Doug at Arizona Wholesale (800) 877-0771. He is one of my favorite vendors and might be able to tell you more. |
| QUESTION NO. P1026-9: I have two Emerson TC2555's in my service center with the same problem. Both of them are dead, no power. It looks like the HOT is bad but when replaced, there is no change. Before I order schematics I was wondering if there was a common problem on this model. |
| Problem components for this symptom include the IC501 regulator IC, usually STR30110; R507 = 47 ohm, 1/2W. off the regulator; R521 = 4.7 ohm/3 W.; and sometimes R503. Also check cap C435 = 1 uF @ 160-200V and check/resolder the horiz. drive transformer, since the HOT had blown. If it continues to blow HOT's and regulators, the CRT may be causing this by arcing, and need replacing. |
| Check for small coil in horizontal section (generaly no.2010). If it is open or small blue coils. Also, replace all caps in this section. |
| QUESTION NO. P1030-2: I have a 12-year old RCA 28" TV, Model#FPR 720 that has an intermittent high pitch sound from back of set. Muting the volume has no effect. Which component is most likely responsible? |
| The squeal you hear is coming from the high-voltage transformer. To get rid of the noise, it will have to be replaced. |
| QUESTION NO. P1030-3: I have a Mitsubishi VS-5006R Bigscreen TV. The red tube horizontal adjustment will not let the beams converge. Although the red tube will adjust up and down as much as the other tubes, it will not adjust up enough to converge with the other beams. I can find the focus and other beam adjustments for the tubes, but no adjustment for raising the red beam up so that it will converge. |
| First, adjust the red static convergence for approximate center. Second, readjust the red mechanical centering magnets in the neck of the crt. |
| Probably have a problem in the convergence output or correction ckts. Check the output devices and for any electrolytic capacitors that may be changing value [leaky]. The centering rings on the yokes should allow enough vertical and horizontal movement for center static setup. However, dynamic adjustments must have a fully functional convergence correction circuit. |
| On the MITS VS-5006 it is possible you have bad power resistors feeding the red stk-convergence ic. Compare VCC voltages between the red and blue stk packs. If they are the same, you may just need to adjust the red mechanical centering magnet on the neck of the crt. |
| QUESTION NO. P1029-7: I have a Sony 27" KV-27TS27, Mfg date 10/91. Audio is emitting a high pitched noise. The louder the volume, the louder the noise. It is not the speakers, externally wired speakers do the same. Audio is occasionally muffled and takes time to come through. Approximate part cost? |
| You need to replace the IF module. The part # is on the shield. |
| This model has a common problem with sound bad of all natures, as all models using the sound module SBX 1637-11. Available at Dalbani, Mcm or most part stores. |
| QUESTION NO. P102-9: I am working on a Sony TV KV27ts27 that came in with a power supply problem, resistor and diode fried. I replaced the components. The picture now comes up but is very dark. I do not have a remote for this set and am wondering if it is just a menu adjustment of brightness and contrast. Is there any way to access the internal settings without a remote (or should I suspect another problem)? |
| You need to get the remote for the set. It is the only way to access the menu. |
| QUESTION NO. P1028-7: Zenith Sentry 2 TV, turns on , turns off but has no picture or sound. |
| Model # would be of assistance, however, check for the little tags having part numbers on them for the complete circuit modules. Numbers start with 9-XXXX-XX. Suspect sweep/HV modules, especially broken or cracked connections on those modules. |
| QUESTION NO. P1027-1: I have a Sharp 20rv69 TV. When you turn it on, the picture is dark and out of focus. After it is on for an hour or so it gets better but picture is still weak. The voltages on the red, blue and green output transistors is 20 to 30% low but I cannot seem to find a reason why. |
| Possible a very weak CRT, low G2 voltage, or even low HV to the CRT. Also, have you confirmed the B+ level is correct, this would affect the entire system. Low voltage at the video outputs caused by excessive current flow or low supply from your source; power supplies. |
| QUESTION NO. P1027-7: Pioneer pro-119 RPTV. After accessing the first factory ADJ mode, the unit makes a loud but short static burst when changing channels. Delay between channel changes is also signifiantly shortened. Just want to get rid of the static burst. |
| Try reprogramming the channels into memory [autoscan]. |
| QUESTION NO. P1025-6: I have a Hitachi color tv model# CT2670B. There is a white line across the screen from left to right and the sound is still normal (can still be heard). |
| Sounds as if you have no vertical deflection. Check supply voltages to vertical output devices. Check electrolytic capacitors in supply and deflection checks. |
| QUESTION NO. P1023-1: I have a Sony model kv1973r that has distorted audio half way through the volume range. Speaker is fine and solders are ok too. |
| Check the Power Supply Capacitors. The value of them/it should be 1,000/20,000uF and 25/75 volts. |
| QUESTION NO. P1023-6: Looking for the specs or an alternate part number for a component on a Gold Star TV, NC-95A Chassis P/N 111-D59A. The component is Q402 P/N D1555. It is the horizontal drive portion of the board and is causing intermittent collapsing of the display. |
| 2SD1555 is a Toshiba 5 Amp horizontal deflection transistor, with internal damper diode and 50 ohm base-emitter resistor. Mouser (800-346-6873) lists it for $3.25, no minimum. |
| QUESTION NO. P1020-2: I have a GE model 25GT520 (chassis CTC177AF2) that is not displaying proper menu setups. All of the soldering around the tuner has been done. The EEprom data looks reasonable. Setup for the "CONTROL" menu is missing three out of five functions. They are Sleep timer; Stereo; Tone. The background color of the menu is correct. "ALARM" menu and "ADJUST" menu are all okay and function properly. My main problem is the "SETUP" menu has the proper background color but all of the functions are wrong. It has the same functions as the "ADJUST" menu and it controls them also. With this problem I cannot turn on the speakers nor program the channels. Other than this, the set is working fine. |
| Even though the values may be correct, the eeprom will still have to be replaced. Record the values before replacing the chip as they are probably ok. The hard memory portion of the chip is what is corrupted. There is no way to reload this information from the front panel buttons. I have seen this symptom before where some of the menus are missing, or the remaining ones are spelled wrong, depending on the degree of corruption. |
| QUESTION NO. P1013-4: I have a Sony KV-A2922U (approximately 1992 vintage) with no vertical deflection on power up. Have reseated connections to yoke. Cannot see a service switch inside. Any tips? |
| Failure in vertical deflection circuit or supply power circuit to same. Suspect vertical output devices and electrolytic capacitors in vertical circuit. |
| QUESTION NO. P1013-8: Zenith SZ1961W using module no. 9-214. Need audio output 1-c part no. 221-178 or Zenith kit no. 905-91, Zenith does not have kit at this time. I tried a TDA 4190 but volume stays at maximum. How can I convert the circuit to make TDA 4190 work or will ECG 1633 work if I can find one? |
| Pin # 13 on the device is the volume control. Check if the bias @ this pin varies with change of volume setting. If it does the IC is probably defective. If it does not then you have other problems in the ckt. |
| QUESTION NO. P1013-3: I am working on an RCA TV chassis ctc 167c. When power button pushed, led blinks thre times then shuts off. All standby voltages are present and processor and reset are receiving proper voltages. Processor crystal was replaced along with cr 4103 and c4605. Voltages at q4161 collector 24.2 and r4163is good. Shorting pin 18 ic 3101 to ground does not bring up high voltage. |
| Check your standby voltage @ collector of horizontal output transistor, should be approximately 140 volts. If you have no standy voltage, find out where in the power supply or distribution system you are losing it. A good circuit diagram may be of assistance. |
| QUESTION NO. P107-9: Need pin-description of following TV IC's: DPU 2543, PVPU 2203, DTI 2222, SPU 2220, ADC2310 E, APU 2471, CCU-SCHNE-13. All these IC's are coupled on Schneider Digitech STV 7150 / typ DTV 7032 /TV set. |
| You may try http//www.ba-karlsruhe.de/chipdir/chipdir.htm to find more info. |
| QUESTION NO. P108-1: I have a Sony (PAL) TV, type KV-2581 and I need to enter the Service Menu to make some adjustments. |
| Sony RA Chassis service mode may be entered by the following sequence of buttons on the Sony remote. Switch the receiver off, press display, 5, volume up, and power within one second of another. Set should come on with a menu display. Buttons 1 & 3 select register to be modified, buttons 2 & 4 select the data value. To write changes to the registers, press 8 and enter button and power off. Suggestion, write down the original data values before changing so you can return to them if necessary. |
| QUESTION NO. P108-3: I have a 63cm CTV AWA Thorn Model QM100 63T3 Chassis with remote control. The set shuts down intermittently for a few seconds then restarts. This only occurs when the set has been on for a period of many hours. Does anyone have a clue as to where I should start looking? |
| Possible something changing in regulated B+ causing the protect to go into effect. Monitor the B+ to the hv section while the set is in extended operation. Also, when the set is acting up you may try freeze spray to cool certain components to see if they are the affected items. Intermittent problems like this can be a real challenge. |
| QUESTION NO. P108-5: I have a 1982 Quasar 25" console (model TU916OUS, chassis ALQDTS980) experiencing vertical collapse. Solid white line across screen with approximately 6" of raster showing below the line. Replaced Q451 & Q452 vertical ouputs which re-established 6" of raster (was originally flat line only). |
| Suspect defective eletrolytic capacitors and probably changed value resistors within the vertical circuit as well as the supply to the vertical. If the supply is to low to the deflection, you will have limited sweep. |
| QUESTION NO. P918-8: I have in my shop a Mitsubishi CS 2012RA. The problem is audio, the sound comes on, good volume then fades to nothing. It may stay that way for 5 or so minutes then comes back up to a good level, when it does, it sounds like an old time radio, really tinny. Has anyone out there had a similar problem? |
| If my memory serves me corectly(??), replace BP330 Audio band pass filter. You can sometimes test it by removing it and turning it around. |
| QUESTION NO. P104-1: I have an RCA model number f191220bk chassis # ctc175l2 that does not pick up any channels, just snow. But the on-screen display works. I was told it had previous horizontal problems but that is unconfirmed. I have measured 5V at a 120 volt test point TP4108 and 21V at a 12V test point TP4103 as well as 0V at a 12V test point TP4731. Can someone confirm these test point voltages and is the eeprom causing this? I do not have a schematic. |
| Repair the tuner and mpu grounds per RCA repair info. Replace the Eprom preferrably with one that has been pre-programmed. Should the Eprom not be available pre-registered, either enter all the data manually via the service menu or use Chipper Check to enter the data thus providing proper info for tuner parameters, etc. |
| QUESTION NO. P104-5: I have an RCA 25" model X25101GS, chassis CTC177AA. The set works fine for a while and then the screen begins to shrink. Then it cuts off and cannot be turned on unless it is unplugged then plugged in again. What could possibly be the problem? Other people I know with the same model have a similar problem. |
| Repair the tuner and mpu grounds as per RCA Tech Data. May eventually require Eprom replacement if not correctly repaired. |
| QUESTION NO. P102-1: Have Mitsubishi vs-406rs big screen TV set has no picture or sound. There is no H.V. and picture tubes not lighting. There is 132 volts at the col. of HOT. 50 volts at J118 reads 0 volts. Reg. ic 991 has 145 volts at the case. Read voltages at the three pins of ic991, they read 122 volts 0 volts and 132 volts. 170 volts at R546 reads 132 volts. No 12 volts at R587. All fuse res. and diodes check good. HOT checks good. IC protector checks good. Relay on power supply is working. Main power light comes on as does the channel indicator. |
| Check the B+ at the horizontal driver transistor. Also check horizontal drive signal from source through driver to base of hot transistor. Common problem is failure of yoke windings but this usually blows either the B+ fuse to the sweep or the cpt to same area. Possible FBT problem, but quite rare. Possible open in driver transformer or bad solder connections at same. |
| Check fusistor and 2kV diode feeding SCREEN voltage to CRTs from flyback. |
| QUESTION NO. P928-9: I have a Sony KV-2063 which can run without problems for hours (days!) and then suddenly switch off and on very quickly with random text showing on my screen. This can also happen in reverse ie. set is off for hours then suddenly switches on by itself. I have replaced the voltage regulator and the Protection Module with no success. I am beginning to think that the micro is acting up. Has anyone had a similar experience and what can be done about it? |
| Very good probability, also check the memory ic. Also, look for possible solder cracks in the area of the micro, specifically associated with grounds, reset, and source. |
| QUESTION NO. P925-1: I have a Sanyo television, model DS25330, that has lost channels 2 through 47 with just raster seen and heard. Channels 48 and up have perfect video and audio. After checking all solder connections and finding no other problems, where would be a good source to get this tuner? The model number on the tuner is 1AV4F1BAM0010. |
| Sanyo authorized parts distributor or direct form Sanyo Corp. |
| The first thing to do is check the band switch voltages it is probably not the tuner. |
| This Mitsubishi chassis had a problem with a bad glue. The glue turns brown and begins to eat away at the circuit board. While doing the damage it acts somewhat like a conductor and may cause intermittent operation, erratic operation or complete failure. One of the places where this glue attacks cuts a trace in the vertical. Best to remove all glue and bridge and damaged foil. |
| QUESTION NO. P923-9: I have a Sony TV model kv32S22 with intermittent trouble. The set will run three hours, sometimes five or more, then shuts down. Hitting the power button will return set to normal again. I have checked for bad connections, resoldered any in question, replaced error amp detector on power supply board. Monitored supply as well. Changed flyback with oem, changed video / chromra processor ic, monitored beam current. Set ran two days at shop fine, all day. Customer gets the set, one hour starts doing it again. I tried calling Sony at their 900 # but can never get through. I am lost on this one, any help? |
| Your Sony is acting just like one I had in the shop. Finally found a bad connection from the circuit run to the solder pad by taking a stick and pushing down on the board all over the place, tapping on components and moving them around. I tried cold spray to no avail. These are hard to find and takes time. |
| QUESTION NO. P922-4: Is anyone familar with RCA #ctc185? Vertical problem, top half foldover with pincushion lines. Also, will not change channels. |
| Check the capacitors around the vertical IC, in and around the flyback, but most of all - remove the shield on the tuner and resolder all ground connections. Use a strong magnifying glass and look for cracks in the solder joints. This is a big problem with the new ctc chassis. |
| QUESTION NO. P923-7: I have an Emerson ts1995 television. The picture either rolls or has vertical jitter. I have checked the vertical section and everything seems to be ok. The circuit board fits into two slots, one on each side. If you move the back of the board up and down you can start or stop the vertical movement. I have checked for cold and loose solder joints but can find none. |
| If moving or flexing the circuit board stops the roll and vertical jitter, you probably have a bad solder joint some place on the board. It is easier to just resolder all connections in the vertical circuit using kester liquid soldering flux as a wetting agent. This saves many hours of shop time. Also, jewelers loop magnifiers help tremendously in identifying those hard to locate, bad solder joints. |
| QUESTION NO. P827-1: Sony KV-1440E's power supply is screaming, even when disconnected from load. Before that, the set was smoking but cannot find any burned components. |
| Check for shorted diodes and dried up electrolytics in the power supply. The screaming you hear is probably due to one or both conditions being met. |
| QUESTION NO. P923-3: Memorex 25" ctv comes on for about 1min then shuts down. Picture and color good, cannot get unit to restart unless unplugged and replugged in. Picture lasts longer if set sits for a day or so (approx 2 min), end result is same. Suspect bad caps in p/s. |
| Suspect the b+ is going too high or the hv protect is shutting unit down. Regulated B+ should be about 125 to 130 @ the fbt. If this potential is too high, it will also trip the protect ckts. |
| QUESTION NO. P923-10: Working on JVC 27AV820. Set came in dead, possible power surge? Do not have a print yet, but this is what we have. About 145 volt on HOT, 5volt standby. No volts on horizontal drive when power switch pushed. |
| B+ @ 145 seems too high, suspect regulator problem. Try on variac to see if unit starts at lower B+. Also, suspect anything in the standby supply, including the +9 reg ic. |
| QUESTION NO. P921-2: The NEC model DT-4861-S has the issue of ring cracked solder at Q401 and Q402 vertical outputs due to the heat of the transistors. Is there any way to cool this area and prevent the compromised integrity of the solder? Maybe something like a computer fan intalled near the board? |
| Anything to get rid of the heat directly from the pcb will help. However, with these sets becoming more than seven years old, and their unkind history of frying the crts, why bother? Not to be cynical, but I have personally installed over five hundred crts into these NEC televisions, some of them within three years of purchase. Thank God NEC stop producing consumer products! |
| QUESTION NO. P918-6: I keep running into the same re-occuring symptom on several different brands. The TV's have sound, but no picture, no raster, no video, just dark. No heater lights, and crts are not lite Power or standby power light is on. I have read many of your faq's, and they talk about dried caps but do not give location numbers, or what board. They talk about crt fluid levels, where are these fluid chambers located? I have repaired many by replacing the flyback module, and tripler unit. This gets expensive! Is there a cheaper fix? How do you tell the difference between caps in the comb filter knocking out video, and the connection in the high voltage causing no high voltage no video? Help! Question # P530-1 seems to be very close to what I have experienced, but states that heaters are not on, the answer given says since filaments are lit I assume you have high voltage, I am confused! Heaters and filaments are just different words for the same thing, right? In most of my cases, I have no heater lights and no high voltage. I still have sound. |
| Fluid levels are specific to projection tvs, not direct view. If the fluid level is low, look for damage to any pcbs below the crts. The material is elthlene glycol and can not be easily cleaned from the pcbs. Sound but no raster?? Sounds as if the derived power supplies from the horizontal sweep are not functioning. No filaments also indicate the horizontal circuits are shut down. Trouble shoot the power supply to the horizontal output and drive circuits. If the horizontal output device is defective then also consider the fbt may be defective. To develop hv and filament currene, the horizontal circuits must be functioning. Also, any component in the derived power supply and deflection circuits may cause the horizontal not to function. |
| QUESTION NO. P919-4: Have a Mitsubishi TV CS-26EX1 sn039213. After a couple of minutes warmup, the colors get washed out and the picture fades to black. It happens more with hot or humid weather and appears to be thermal related. Audio is fine. |
| If your set has a stand up PIP module suspect C-7001, 4.7 ufd @ 35 wv. SMD device leaks electrolyte and eats trace off board. Also, other smd elect caps on same pcb have been know to cause similar problems. |
| QUESTION NO. P919-7: I am working on a Toshiba 31 inch, chassis# TAC8957. Keeps blowing the HOT. When the deflection yoke is removed, voltage on the HOT is normal, replaced D406, D408, D302. C442, 443 test good. Is the yoke bad? |
| Highly probable, I have seen quite a few on projector sets made by Toshiba. Would not surprise me to find same problem in diectview also. |
| QUESTION NO. P917-7: I am working on an RCA 35" CTC169EJ5 "Dead Set Syndrome". Customer described it dying as hearing a loud snap and then TV shut off. Checked all supplies in standby mode, all are as they should be! (I have read many of the responses here and actually replaced many of the components recomended for repair but to no avail!) Checked U3101 (pin 38) "power on" output of Micro when "On" button depressed does not go to 4.9 volts bouncing all around. Removed Q3304 I believe is the next component off this pin and pin goes to high 4.9 volts as it should. Is this a function of the output of the Micro (pin 38) being bad so as soon as you load the output it fails (replace Micro) or something down line (switching transistors being shorted.) |
| Also suspect the HV-Focus block. Remove the HV lead from the block to the anode connector. Try the set to see if it will switch on.Switch set off and remove all power from chassis. Very carefuly discharge the HV from the anode cap using a good ground lead to dag. If set will work without bleeder/focus assembly attached, you found your problem. Also can cause similar problems in projector tvs. |
| CTC-169 Chopper Supply Problems. Change Q-4101 #200165, U-4101 # 200419, CR-4101 #207878, CR4122 #200158, C-4108 #208002,R-4001 #190487/200444. Usually the cap dries out and causes the chopper to run hot and evetually short out. If your horizontal output is also shorted, cange the pin damper diode #164589 and cap #200149. |
| QUESTION NO. P911-4: I have a CTC 177AH that keeps blowing fuses. I have replaced CR4106, U4101 twice, and R4001 checks fine. Rectifier diodes forming the bridge check ok. HO checks good, but I question the flyback. Also does the ctc 175a chassis use the same flyback as the ctc177ah? If so, I have one I can replace it with. |
| Suspect the fbt, they seem to have a short life span. Check the device numbers stamped on the side of the fbt assemblies. If the 177 and 175 device numbers are duplicate, they can be interchanged. Knowing Thompson, there is probably a different part for the 177 because of the different deflection angles and current requirements. |
| QUESTION NO. P911-6: I have an RCA F27251WN that has a width problem. The picture is too wide for the screen. Cannot find an adjustment for the width. Any suggestions? |
| Suspect the pcc damper diode and associated cap. Common problem. |
| QUESTION NO. P93-2: Have Mitsibishi model #ck-2696c with no color. Everything seems ok with picture coming in black & white only. |
| Try changing the 3.58 xtl first. Check i/o of signals @ signal jungle ic. Check for glue or corrosion on pcb in area of video processor. Confirm proper voltages @ vioeo processor ic. |
| QUESTION NO. P911-9: I have a Quasar T.V. m/n QC-29sx51h. When blue screen is displayed, the picture is purple in the center, blends to red on the rest of the screen and the corners are green. The picture is O.K. if the color and tint are turned down, but color is a mess when turned up to normal levels. The set was fine in the morning but the display came on like this when it was turned on in the afternoon. I only work on computer monitors, so I am looking for a place to start. |
| 1. Degauss the CRT. 2. Troubleshoot the degaussing circuit. 3. Warped shadow mask in CRT. |
| Suspect purity problem or degauss circuit problem. |
| QUESTION NO. P98-7: Have a JVC HR-D970U and JVC made Zenith VRG520HF that both have the same problem. Plug it in and the switch mode power supply clicks but no display and unable to power on. Cannot seem to locate the problem in the power supply. Any thoughts? |
| Replace the two caps in the Power Supply on the 3.2V line. |
| QUESTION NO. P819-7: I am in need of a part for a 1954 Dumont TV. The # on the part is 03121601, it also has printed on it 500 mmf 20kv. I was told it is called a "doorknob" by an old time partsman. |
| I have a 500mmfd., 20kv capacitor that is probably the one you need for the old TV. It is light brown in color and has threaded holes in the ends for screw-in solder terminals. It is about an inch in length and an inch in diameter. You can have it for freight. |
| QUESTION NO. P818-7: Am working on a GE 5" Color TV Model 05GP008 which, when initially turned on is extremely blurred. If left on for an hour or so, it clears up. Sound is OK, tuning OK, colors OK. Can you point me in the right direction? |
| Your problem sounds like a soft crt.. But you can double check by measuring the focus voltage when bad verses good. If it is the crt there will be no change. You will need a HI-Z probe and a Digital meter. |
| QUESTION NO. P811-2: I am working on an Hitachi TV model CT3020B and am in need (ideally) of a new power supply, but cannot find a supplier. If that can not be obtained, a schematic. The p.s. containes an I.C. labeled STA8012 and I suspect this as being bad but am having REAL trouble finding any data on the I.C. |
| You probably have a shorted diode in the secondary. The 18V zener is a good suspect. Also, CHANGE the 6.3V caps and the 1@50 cap. |
| QUESTION NO. P98-4: I have a Sony 68cm CTV model number KV 2966AS. Line driver STRS5741 blown. Does that mean I have a short somewhere up stream? Perhaps a transformer with a short to earth OR a dud Capacitor? |
| Probably just the regulator ic took a dump, seen it before. However, make sure the hot is good. If shorted, you may have a defect in fbt or derived ckts. |
| QUESTION NO. P98-3: I am repairing an RCA Model #F25652BL TV, Chassis # 187AB. The problem with this unit is only channels 51-59 are present, all other channels are snowy. The TV still programs the channels, but nothing but snow appear on channels 2-50. |
| First, resolder all ground tabs and ground points within tuner and mpu ground shield tabs per RCA service info. Second, order a new Eprom, preferrably one with data parameters already entered, or a copy of the RCA diagnostics software for setting the parameters in the new Eprom. Third, confirm that none of the smd devices within the tuner area have been solder splashed, moved, or overheated during the repair procedures. |
| Sharp 25J-M & 25K-M televisions having strange symptoms. S/A only osd and menu without audio or pix, switches from blue screen to neutral by itself, parameter changes by themselves [pix & audio settings]. Check on top of pcb to see if there is corrosion in multiple areas, especially around the mpu ic. We have found a couple sets with this problem. Cabinet and crt show no trace of fluid spillage. Cleaning corrosion from pcb and replacing damaged components seem to fix problem. No guess as to where the material came from or its composition. |
| QUESTION NO. P813-9: I have a Zenith SJ2065S5 that has caused me some service problems. The regulator in the power supply ICX3431 (STR53041) and Q3431 (121-1264-01A) keep blowing after running for about an hour or more. The STR53041 runs very warm during that running time. Most times, it fails after running for a few hours but only after I turn it on the next morning. I have changed R3432 a 180K resistor and the filter C3432 100ufd/50volts. My substition for Q3431 is an ECG123A and a STR53041 from a source other than Zenith. This regulator seems to run hot in most of these models but I have not had a problem like this one before. Is there any information about this from Zenith or someone who can give me some help with this one? |
| Do yourself a favor and replace the complete module from Zenith Parts Department. Then, when it fails again within the next two hours you have a warranty to fall back on. |
| Q3431 crosses to NTE194. Check for burn resistors 15 + 47 ohm in front of reg ic. BUT I have had this problem many times Replace CRT. It shorts or is leaky. The chassis is not the cause. |
| QUESTION NO. P814-3: I have a Toshiba TV that I cannot get any picture or audio from. The orange power indicator light comes on, but no other functions work. |
| Anything from the B+ power supply through the deflection circuits and protect circuits. Not knowing specifically the model or chassis I can only guess. If it is a projection tv suspect probably shorted yokes. |
| QUESTION NO. P824-6; TV Mitsibushi 66cg06. It is flashing intermittently. I have changed the tuner, ic701, la7911 cables on tuner, removed glue on board. It works fine on video and audio in or if I inject a i,f signal. Any suggestions? |
| Saw Filter?? |
| QUESTION NO. P824-2: I have been working on a Nap Sylvania chassis 26c8-01. The set cannot be turned on. There is no 5volts for the power on. I have the main power coming out of the bridge. The set has a remote and the first problem was the scr401 was shorted and the r403 neg cold resistor was cracked. The switched mode transistor is not working. I tested every transistor, diode, and resistor in the power supply circuit. The voltage on the 5 volts is about 2volts. |
| Remove any loads from the 5 volt source and see if the voltage comes back to around 5v. If not, check the source feeder and regulator. If it does, follow each load lead to find what is shorting out the supply. Suspect the mpu, memory ic, and tuner. |
| QUESTION NO. P93-9: I have been working on a Magnavox TV model number HD2502 a101 and chassis #25s102-00DD. I just replaced the hot and powered it up. The set turned on but had a black line across the screen and there was a high pitched noise coming from the set. I am not sure if it was coming from the flyback or not. After a few minutes, the hot shorted again. I have checked Q400 and R407, they both seem to be ok. I did not have a chance to measure the 130 volt reg because of the hot shorting out again. Do you have any other suggestions? |
| I will bet the fbt is toast. If the hot blew quickly, and felt especially warm, the flyback probably is bad. Other things may be any thing in the fbt derived power supply and deflection. I would check the fbt with a ringer or just replace it. |
| QUESTION NO. P93-6: Repairing Zenith color TV model #SD2501W. Channels 10, 11, 12 sometimes show snow. As well, sometimes causes same problem on other tv attached to splitter (only when the three channels are showing snow). First thought, it was cable. Should the tuner be replaced, and if so, where can I find the part number for the tuner? |
| Part number for tuner should be on a tag attached to the tuner. Should start with 175-. |
| QUESTION NO. P817-8: TV GE 27GT614FE1. I have replaced STK 730-010 & diode +b. When I turn on TV, it burns out again, same parts. Any idea ? Where I can buy the parts? |
| I do not have the exact answer you want but I do have some info that may help. If this is a ctc177 chassis I have the exact same problem (ctc177ah) (rca F25671SE). I found cr4106 shorted, U4101 shorted on 09, 10 and 11,12, and the 5A fuse blown. If I replace the parts the same ones are taken out again. They is an updated U4101 and it is STK 730-130 and I believe it crosse to ECG 7125. The CR4106 crosses to ECG 577. I have found that the HO checks ok and I found a few high voltage caps that checked bad on a Sencore Z meter cap checker (very good meter by the way) 2.2 uf 200v and 10uf 200v. I also did a ring test on the flyback and it checked funny on pin 1 and 2, and 2 and 3. I suspect the flyback to be bad but I have not had a chance to replace U4101 again. |
| Did you insulate the IC from the heat sink? If not, you just shorted the raw B+ to ground again. RCA does not include it when they sell you the IC. |
| Had this same problem. C4105 10uf @ 200v is open and causes CR4106 to short, which shorts U4101 regulator. My set also originally had CR4109 zener shorted. Suggest using original Cr4106 164589. Zener is 7.5v. |
| QUESTION NO. P818-6: Working on a Samsung TV/VCR combo model MVR-3100. There is a constant high pitch squeel if the TV is powered off. As soon as the TV is powered up, the squeel goes away and everything works normally. The squeel appears to be coming from the hot/cold power transformer (T801). Is the transformer the likely fault, or should I look for something else? |
| Check/replace the electrolytic caps around the transfomer and on both sides of the heat sink in front of it. I had the same problem with one a couple of months ago. I found two bad caps. Forgot ref #s. One was next to heat sink towards back of board, other was close to transformer towards front of board. |
| QUESTION NO. P818-8: I have a Sharp color TV model number 51 only two years old. The problem is no picture but audio is ok. Line and field drives seem to be ok. Can get a raster with flyback lines if I turn up screen voltage. Rgb drives are ok {I even replaced ic801 mc44007}. This chip does all the video processing.the lead for the heater voltage is a four wire one. Pin 1 has 180v on it pins 2, 3 are ground. Does anyone know what pin 4 should have? Has anyone got any other ideas? |
| D1002, which clamps the video signal, goes leaky. This killls the rgb to the crt base. Replace D1002. |
| QUESTION NO. P730-7: I have a Samsung TXB2525 TV that comes on when plugged in. There is no control over the TV with remote or direct. To turn the set off, you must unplug the unit. There is no sound and no picture but there is high voltage. |
| Have you checked the power relay? I have had a few sets that did the same, the contacts where arced closed. The micro does not have a chance to reset first at plug in, that is why no functions and no pix + snd. Check AC pins of relay for short. If so, unsolder one AC pin of relay, plug set in, reconnect pin with a jumper, set will power up. Then push power "on" switch and pix, snd and functions should return. |
| QUESTION NO. P818-1: TV Sony kv-27hfr. I have replaced power supply out tranzistor. TV was functional about 1 month and back again with same tranzistor exploded. I have checked components around but without success. I have replaced tr. and after 1 month same story. Any idea? |
| You did not state that you used exact Sony replacement parts or generic? Try the original Sony part, also check for possible leaky caps in filtering checks. |
| Replace control ic 601. |
| QUESTION NO. P84-3: I have a Zenith Sentry 2 sls2504. The vertical display started to intermittently shrink to about 1/3 the screen. This went on for two days then it shrank to a thin horizontal line. Is there anything I can check as far as bad components before I replace the whole module? I do not normally work on TV's but I am an ET. |
| Check supply to vertical output and active chip. |
| Repair bad joints on vertical ic. |
| QUESTION NO. P86-4: TV Sony Model KPR41EXP95 have horizontal lines in bottom of picture and the begining (left) of lines looks like many haft-Sine wave form. It is not problem of tuner. May be caused by some capacitor? Any ideas? |
| Vertical, pincushion, convergence, then guess. Probably not a power related problem. |
| QUESTION NO. P810-9: I have a Zenith Model #SJ2743LK which has a vertical hold problem consistently on channel 10 and occassionally channel 12. All other channels work fine. Can anyone help? |
| Clipped sync from the cable system can cause this problem. Try with off air signals or a good, stable generator. Check source with another brand of TV to see if problem persists or is only specific to Goldstar/Zenith. BTW, they do have reasonable tech support for authorized servicers. Scoping the composite video while tuned to these specific channels then comparing the sync pulses height and width may give you a clue. |
| QUESTION NO. P814-8: I have a SHARP model 40KD855 40" big screen TV. The red/blue - horizonal/vertical adjustment will not respond when placed in the "test" mode. Normally, a horizontal & vertical crosshair should appear when in the "test" mode, but only the horizonal line is present and the red and blue adjustments do not respond. |
| Probably a failure in the convergence output circuit. If the unit uses the STK type outputs, it is possibe that they have failed which could also cause fusing devices in the convergence to fail. |
| QUESTION NO. P817-6: Working on a CTC146M. TV is having an intermittent problem that I cannot figure out on two separate units that came from the same motel. Both units will usually auto-program when powered on, then after some time they will go to static on the screen. Seems like if I push the tuner one way or the other it will be OK. Definitely seems like a solder connection somewhere? Is it true that these chassis' are known for tuner problems? And is there any fix to this? Help. Need an answer urgently! |
| Very good possibility, you may try resoldering the grounds and any suspicious connections within the tuner or just replace them. |
| QUESTION NO. P817-2: Hitachi CT7881B TV. Problem intermittent, then final loss of cable channels 2-48. Upper channels are o.k. Any ideas? |
| Probably the tuner. Check for broken grounds and ring cracks within tuner or sub with another to check. |
| QUESTION NO. P813-5: I have been working on a Magnavox model HD2502 a101 chassis #255102-00DD. I found that the HOT is shorted and I beleive that the Flyback is bad. I cannot seem to read the manufacture part number on the HOT. Would you know what it is? Also on the flyback there are two numbers, I am not sure which one to use for a replacement flyback. Before I buy a new flyback, is there a simple test I could use to check it? |
| I think there is a misprint of the chassis #. If it is a 25S1XXX, the number on the flyback that starts with 003XXXXX can be crossed by any NAP parts dist. Also check the 130 volt reg. and Q400. If R407(100ohm 1/3 watt ) is open, you could have a fault in the x-ray latch. Been there. |
| QUESTION NO. P816-9: Have a lightning damaged Mitsubishi CS2611R which is now functioning fine except for OSD which is missing.Have changed micro and checked what I thought was everything in OSD checked. Horizontal to micro ok but slight distortion of waveform on vertical pulse to micro. Had damage to vertical checked initially. |
| Set has been fixed. Problem was IC501 - 9v regulator - 78L09A. (9.2v measured 10.2v). |
| QUESTION NO. P84-9: Toshiba TV model CF2655F. Channels will not lock. Replaced tuner C175, C171, Q171. R171 ok. Sync pulses reaching ICA01 at pins 26&27. Pin 36 of ICA01 goes high to low as channels try to lock. |
| That repair is a killer. I do not remember the location #, but there are two 1/2 watt resistors at the flyback area that open. |
| QUESTION NO. P86-5: I have a dead TV Magnavox 19 inch model xr1938 c121, chassis 19s403-00aa. Every major component tests ok. HOT ok. 165v dc at filter cap. |
| Change IC430, check Q400 for base/emitter short. Also check solder joints and dropping resistors in horizontal drive circuit. |
| QUESTION NO. P814-2: I am working on a 27" Quasar T.V model no. SP2716k. There is no picture. Changed IC LA7836, worked fine for about three weeks then same problem occurred. I do not have a schematic. Any suggestions? |
| Vertical amps usually go bad for a reason. Change the 100uf/35 volt coupling cap for the feedback circuit, then change the IC again. |
| QUESTION NO. P812-9: I am working on an RCA with a CTC130 chassis. It works fine when first turned on cold, but after a while, anywhere from a few minutes to a few hours, the audio and video signals will drop out leaving a snowy screen and hissing audio. When this happens the channel LED display goes completely out. It will stay this way until the set is shut off. I removed the cover to the tuner module and now notice that it takes longer before acting up. The power supply to the tuner module stays constant when the set is working fine and when it is acting up. |
| In the tuner control you will see a bank of 5 caps (220uf,330uf,470uf,100uf& 10uf). Change all of them and resolder all binding posts, including the ones on the back side next to the processor. |
| QUESTION NO. P721-10: I have a NAP 25c8 chassis which has been dealing me fits. The set works fine, but the vertical will collapse down to a single line for one second intermittently. The set plays fine otherwise. The vertical ouput IC 580 has been changed, so has the IC201 if/sound/sync chip. The voltages seem to be ok. This seems to be some form of shutdown of the vertical circuit but I have no idea what to check or change next. |
| Check all the small disk caps around the vertical chip. I had one do the same thing to a computer monitor, it would collapse and pop back up whenever it felt like it. |
| QUESTION NO. P83-7: I have an RCA TV Chassis CTC187; that looks like it has a horizontal hold problem. I cannot even bring up the service menu without it looking all twisted. What is the problem? |
| In order to see parameter and value numbers on screen when H. frequency is off, do not connect cable or antenna. Set value to 76 then parameter to 01, adjust value to 14, reconnect cable or antenna and fine tune H. freq. Do not forget to solder tuner and system control ground shields. If this does not restore set, replace EEPROM. |
| QUESTION NO. P84-6: I have a Sharp 25" model #25H102 that has a bad power regulator IC #RH-iX0359CEZZ. Do you know of a source of supply for this IC? Sharp says that it is NLA from them. |
| MCM Electronics (800-543-4330) is currently listing this as "RH-1X-0359 CEZZ" <sic> for $ 11.04 a piece. |
| QUESTION NO. P81-8: I have an Emerson model TC1351 that has no vertical or sound. I have found Q407 open and R438 burned and replaced them. Still have horizontal line, no sound and R438 gets HOT! Also replaced vertical IC LA7837. |
| Possibly the audio output device{s} are shorted? Obliviously there is still an overload causing the fuse resistor to scream out for attention. Also, check the electrolytic capacitors in derived supply, audio, and vertical ckts. |
| QUESTION NO. P81-2: I have an RCA G31100CK. Had a blown fuse resistor .29 ohm, replaced and tv seems ok except no channell 9 . Any ideas? |
| Not knowing the specific chassis I would probably suspect the solder connections around the tuner & MPU or maybe the E-Prom, if it is a chassis later than CTC177. Chassis before the CTC170, may be in the tuner or controller. |
| QUESTION NO. P731-9: I have Zenith model SG2567h that will not respond to customer control to change 'picture'. All other controls respond properly. There are no 'hidden' pre-sets for picture (contrast). I suspect IC2301 (221-518) but would like to prove it first. I have scoped all pins that seem too be related to this with no positive results. I am beginning to have bad feelings about Zenith as I have run into many wierd problems similar to this. HELP. |
| Find the white sticker with the 9-XXXX-XX part number and fix the set. Sure, it would be nice to find out just what is causing the symptom. However, the complete modules are still stocked by Zenith. |
| QUESTION NO. P730-4: Need a cross for a Motorola IC used in a Magnavox TV Chasis L1. IC is Q450. Number on the transistor is 612479-4. I also need D450, diode is labeled 181 ph. The IC is a 3-legged one. |
| The IC Q450 Part# 612479-4 crosses to an ECG966, and the D450 Part# 181 I believe crosses to a ECG519. |
| QUESTION NO. P730-5: I have a Wards TV Model #GSK15126, manufactured by Sharp. The plastic button assembly is no longer available from Wards. Does anybody know the Sharp equivalent? It is similar to a # JBTN-1332CEKA, but not the same. |
| I have gotten parts from HP parts with success. The number is 1-800-227-8164. You will first have to get a part number. You can call their tech support number at 1-208-323-2551 and they should be able to help you there. |
| QUESTION NO. P727-3: I have a problem with a JVC C-140F color TV. When I take channels in memory, if I cut off the TV for 5-10 minutes, all is ok. But if I cut off the power for 1 or 2 hours, all channels are lost from memory. There is no battery or capacitance to maintain the memory on the schematic. I think that if the memory is down, it will be lost after 5 minutes. Any ideas for this problem? |
| I do not believe there is a storage device in your JVC tv. The memory source is via the standby supply and requires constant ac application to be active. |
| QUESTION NO. P727-2: JVC TV #AV27BX5. The problem is that <*sometimes*> when powered down (from remote or console), the screen goes bright blinding white. The remote and console buttons cease to function. The only way user can turn the set off and ultimately return it to normal operation is to unplug it from the wall for about 5 seconds. User goes through this procedure about twice a month. |
| There may be a 9 volt regulator ic, TO-220 case, near the center of the pcb. Replace it, the thing seems to like putting out less than 9 volts. When it gets low enough, it causes the MPU to do strange things. |
| QUESTION NO. P721-1: I have a Zenith system 3 Direct-View Reciever/Monitor, Model SM2573BT. The PIP screen when activated looks like a horizontal "Rainbow" has been superimposed over the picture. After searching for the difficulty to no avail, I wonder if this is being caused by the Application Specific IC. Has anyone seen this before? |
| Having failed to locate the problem, you may need to get the signal module and pip module to cure this item. You may try one of the items at a time to justify changing just one of them, check with your parts supplier if they will allow you to do so. Probable on pip module but could also be in video processing on signal pcb. |
| QUESTION NO. P726-10: I am trying to fix a made in Malaysia Panasonic CTV, console model TC-20Z1K. There is a single horizontal line in the middle of the screen. Channels come in fine, sound is good. I have no service manual, printed board not marked where is vertical section. There are two IC's LA7837 and AN5265, which are located near the vertical size control. Can anyone please tell me which one is for the vertical output? |
| Probably the La-7837. Suspect the ic, associated capacitors, and supply sources. Also check for any poor solder joints or ring cracks around component leads. |
| QUESTION NO. P726-5: Zenith PV5263mk2 Lost video, still had audio, smelled smoke. Could find no visual damage. Powered up, smoke from crx3212, crx3212 and cr3419 shorted. do not have a service manual, What other components do I need to check before replacing these two? Fuse fx3468 right by cr3419 ok. |
| Suggest replacing the entire module{s}. Also check the focus, hv block for fine cracks that allow moisture into the distribution area. |
| QUESTION NO. P721-6: I am working on a Toshiba CF3264K television. I have never seen this in a solid state television; when the tv is first turned on, the the picture has too much height. Looks like balloning used to look on the older tube high voltage rectifier. After 5-10 minutes, the picture is the correct size. Where should I start looking in a solid state tv?? Updated information on the problem: Replaced all electrolytics in the vertical, did not fix problem. Tried to cool all components to create the problem that you have the first 15 minutes, but that also did not cause the problem to reoccur. It always fails when it has been off for a couple of hours. |
| Regulated power supply, I'll bet the voltages are t0o high to some of the sources. Also leaky capacitors in vertical. |
| QUESTION NO. P724-9: Sony 27" with number KV27XBR50. The sound disappears from time to time. When present it is clear and loud (the amp ICs seem to be OK). It is probably something small but tricky. Do you know what is it? |
| Check for a small pcb housing many smd electrolytic capacitors. ESR each cap until you locate the defect. Also, some of these units developed cracks in the ground shields of the tuner and mts assemblies which may explain your symptom. |
| QUESTION NO. P724-4: Received Zenith 27" TV, model SM2787BT. TV will turn on and operate fine for about five minutes, then the picture will start to go green. Picture is still sharp, and intermittantly the picture will shrink with white horizontal lines accross the picture. If TV is turned off for 5-10 mins, picture will be normal until set starts warming up and repeats cycle. Could this be an indication the tube is going? |
| Going green may be a symptom of the crt failing. The loss of vertical sweep, however, is a circuit failure, not the crt. |
| QUESTION NO. P724-10: I have a Panasonic CTP2580S in the shop that works fine on channel 3 in cable mode with a VCR. But when hooked up to cable on channel 3, it will not lock on and when it does, it is distorted and the sound is off (like the tank circuit for the tuner is not noticing it). Could this be a saw filter problem? |
| Have had this problem before. Cap c559 is bad causing a lower voltage to the tuning if circuits. |
| Have you tried to switch to another channel and back to channel 3 while connected to the cable? This allows the aft to tune in the channel again. The Cable "channel 03" and Broadcast Standard "Channel 03" may not be the exact same frequency. Normally the atf compensates for this, however, you must go off station and switch back to the station to allow the aft to activate. |
| I have found the problem. It was cap c559 (220uf @ 25v) near the flyback causing the tuner to have problems with cable, but air signals look ok and channel 3 looked ok with a VCR attached. I am so glad for the ecr meters. |
| QUESTION NO. P723-4: I have a 20" RCA standing on my bench. The number is CTC176E. The problem is that it does not want to turn on. They are all of the power supplies (about 160V DC at the main PS, the stand by PS, even the high voltage at the flyback). It seems like the processor is not responding so I changed it. It still does not work. Do you have any idea what might be the reason? |
| Maybe the EEprom. Try removing the tuner bottom shield, check for bad solder, especially the large pin that solders to shield. See http//www.elmswood.guernsey.net/ctc177.html . |
| Try changing the crystal that controls the processor. It is probably 4 or 8MHz . |
| QUESTION NO. P629-5: I have a GE/RCA chasis #CTC175A. I have a picture but it's real fuzzy and I have no sound. When it was opened up there were hundreds of cockroaches that came out of it from being stored in an unpleasant place. |
| The shield of the tuner wasn't soldered right at the factory. Thomson Consumer Electronics has a "repair kit" that consists of flux, solder, a cut-out of the spots to solder, and an instruction sheet. You can do it yourself by de-soldering and removing the bottom shield cover of the tuner, and soldering all the shield tabs correctly, then replacing the shield cover. |
| QUESTION NO. P717-1: I have a Sony KV 2142R which needs a replacement Horizontal output transistor Part #sg-619. A source for an individual part would be appreciated. Set has no sound, no raster , no picture. Transistor is shorted and I am hoping the flyback is okay. |
| Regarding finding a parts source for the h.o.t. for your Sony, try EDS a supplier of factory parts. These parts are still available. from Sony but require a long wait. Keep in mind these older Sonys need to have exact replacements (no subs.) or the set goes into meltdown (believe me). While you're at it, double check the damper diode (this usually fails when a h.o.t. shorts) and order the exact replacement. Check associated nearby components tied in with the h.o.t. as well. Check your B+ regulator transistor also for damage or leakage. Check the horizontal osc. and drive transistors. Perform resistance checks from h.o.t. lead to ground so there are no heavy current paths. I know this sounds like a lot of work but these old Sony types are finicky when the horizontal out fails and ANYTHING left unchecked will assuredly pop your new replacement. Rarer yet, sometimes the high voltage wire to the anode goes bad and needs replaced. I usually plug the set into a variable ac supply and bring up the voltage slowly!, watching the current consumption and monitor the 18v power rail as well. I know this seems like quite an effort but, very necessary on old Sony's, even the factory recommends these procedures. Good luck... I don't envy you ( I'm still working on an old Sony pro monitor which is full of grief!) |
| QUESTION NO. P721-11: Samsung TXG2547 Colour TV having intermittant vertical sweep. |
| Check for ring cracks @ R-310 in derived power supply. I have found a few causing this and other symptoms. |
| QUESTION NO. P715-5: I have a CTC187BD RCA chassis. I resoldered all connections for intermittent picture, now the picture is too wide and looks like pincushion problem on side. Any ideas? |
| Problem may be the pin diode and associated capacitor. Also, I have seen the solder on the pin and damper diodes so poor that they physically fell out of the pcb. |
| QUESTION NO. P630-4: I have a Color T.V.25" Sanyo Model DS-25330. It burns R007(5.6 ohm 1watt)and horizontal output after 20 minutes of use. Any ideas? |
| Suspect flyback and any of the derived supply ckts. Also, make sure the replacement HOT is correct. Also, if the b+ goes to high the unit may shut down or could destroy the HOT. I'd suspect something in the horiz deflection/HV ckts. |
| QUESTION NO. P71-8: Does anyone know what causes vertical jitter on a Philco P2510RW101 (chassis 25S102)? I have seen this problem on a couple of Magnavox, and Sylvania TV's also but was never able to figure it out. |
| If it is accompanied with occasional audio distortion and colour loss suspect the AFT adjustment. If only on a cable source, and specific station, suspect clipped sync level from that specific source. Check the videl input to the jungle ic and the sync level & waveshap coming back out. |
| QUESTION NO. P71-7: I am working on a 25" RCA model G2628OTN chassis CTC157C. Upon powering up, the video is barely visable and the screen has white retrace lines from top to bottom. After a few seconds the little video that was visible is washed out with a white screen with retrace lines. The audio is fine. Also turning the set off and back on after it is warm, causes a delay of about 7 seconds for vertical deflection. Adjusting the screen control has very little effect if any. Is the problem in the video circuit or screen circuit or what? |
| Suspect the video output transistor. Very common on CTC169. |
| This is an answer to my own question. After further troubleshooting with the assistance of the Sam's photofact, I found the luminance buffer transistor Q901 to be leaky from collector to emmiter. I replaced it with an ECG159 and the picture is now fine. |
| QUESTION NO. P71-1: I have a 25" TV Sanyo Model DS-25230 after 20 minutes of use will go to shutdown. Any ideas? |
| Monitor the regulated B+ to assure that it does not go to hign, if the regulated supply is to hign all other voltages also increase, including HV resulting in protect circuit action. A failure in the hv protect can have the same effect. |
| Many of the heating problems I've run across are either components going into thermal runaway or bad solder joints. I've been using a jewelers loop magnifier to positively identify cracked solder joints which will give the symptom you just described. In conjunction with the magnifier, I've made it a point to identify the circuit giving me the problem by chilling it with cold spray. This works very well 99% of the time on heating and shutdown problems in TVs. |
| QUESTION NO. P623-2: I have a Zenith SS1937 with a vertical linearity problem. The set originally had a blown HOT. With a new HOT, the picture squeezes in from top to bottom. |
| Check the caps in the vert circuit and power supply with an ESR Meter. Probably one or more has seen better days. If all else fails, order the circuit module using the 9-XXXX-XX numbers found on the tag. |
| QUESTION NO. P629-4: RCA CTC169 B,35 INCH, repaired pin cush. problem and shorted HOT, now set comes on with vertical line, no horizontal. All secondary supplies are good ? |
| Recheck all you work around the horiz circuit and pcc circuit, I will bet you find a solder joint that you missed. Or did you forget to plug the horiz yoke leads back into the yoke plug? |
| RCA Model No. CTC175C suffered Lightning damage. |
| Replace Fuse,Low Voltage diodes, Q4103 & Q4105 5 volt regulator and 3 lead 12volt regulator. The 12 volt regulator may test ok Change it anyway. |
| QUESTION NO. P64-7: A Panasonic CT27G22 has about 1/4" white line at top of screen when the picture is black. I need to increase the height. How do I enter Service Mode? So far, I can activate self-test with the Power and Action buttons. |
| Short TP8 to gnd, FA-1 to FA-2. A yellow CHK should appear on the screen. Press Action & Volume UP at front of tv. Characters should change to red indicating that you are now in service mode. Power button on remote selects adjustments, B, sub-adjustments, C, CRT adjustments, D, geometry adjustments, and S, factory only setup. Channel buttons on remote select feature, volume buttons on remote change parametre value. To exit press Action and Power for about 2 seconds. TV sill switch off then back on tuned to ch #3. Changing the data in geometry mode will express changes in raster. |
| QUESTION NO. P623-5: I have an RCA (Dimensia) Model FPR2723E-1, Chassis CTC140E. The unit works fine most of the time, but occasionally will power off completely (no picture, no sound) without warning. The set will instantly come back on by itself. This may happen repeatedly for a couple of times then work fine for an extended period. A second unit, same model and chassis has also exhibited the same symptom at various times. Any suggestions on what may be the cause? |
| Remove sub-power board from main chassis. Resolder all diodes and pins on sub-power board, reinstall into chassis. Many times the solder breaks loose from the diodes where they are soldered to this small pcb. |
| Desolder the low voltage sip board (in front of the switching transformer) resolder all diodes, coils & caps. |
| Information for adjusting some manufacturer's TVs via digital service modes are addressed in the june, 98 issue of Electronics Servicing & Technology. The article is not comprehensive but does give information for NAP, Zenith, RCA, Sharp, & MECA [Quasar/Panasonic] televisions. |
| QUESTION NO. P618-2: I have a CTC 146L that is blowing the 1 amp. B+ fuse. The H.O.T. is good and the power supply is OK. I have checked the diodes and capacitors in the derived power supply circuits and have found no trouble. When I remove drive to the HOT by opening the base circuit, it does not blow fuses. I have checked caps in the horizontal circuit and found no trouble. Now I am suspecting the flyback. Is there some check that I can make to verify that before replacing it. |
| A ringing device or commercial flyback checker will give you a yes/no answer. Does the fbt become very warm when the transistor does blow out?? If it dows there is a high probability the transformer is defective. |
| QUESTION NO. P618-4: I have a Sony KV-27SXR10 Television which exhibits intermitent loss of luminence. The picture will turn dark red after a few minutes of operation and can be returned to normal by striking the set. This solution has recently lost its effectivness for the owner. Hence, a faulty solder join is suspected |
| Look for broken solder connections at the regulator ics mounted on the center aluminum heat sink, towards the front of the chassis. Common problem. |
| Find and resolder the main video delay line. On some versions the video board is mounted on the left side of the cabinet (facing the back). |
| QUESTION NO. P617-9: I have a Hitachi 31" TV with intermittant power problems. It will power up to about 5 minutes after it is powered off. Sometime maybe 50 clicks. |
| Check caps in horiz. drive circuit( most likely 100uf/50 volt). |
| QUESTION NO. P65-6: CTC146 has no vertical, just line. Replaced U4501, C4501, CR4501. 24V good and checked tuner solder joints. Any Help? |
| Check the vertical B+ resistors(10 ohm I think) Also check the diodes for the 12 volt run. Had one instance of front control pcb being "Windexed" and two corroded buttons was freezing the system control. |
| QUESTION NO. P69-8: I am working on a Mitsubishi Model CS-2653R with a lose of vert out. IC401 has the following readings 23v pin 7,0.1v pin 6, 0.09v pin5, 0.01v pin4 with a 6.5 mvac sig.,22v pin 3, 2.0v pin 2. Is the lack of an input on pin 5 appear to be the cause or ic401 itself? |
| Suspect the IC, however, if you scoped the drive and found no signal from the previous stage then there are other problems. Most of the problems have been defective ics and supply related as well as dried our caps. |
| QUESTION NO. P617-2: I am working on a toshiba 27in mod cx2668 with dead chassis no blown fuses. Low voltage supply checks good .Jumped the relay and high voltage comes up with green screen and no audio,also no user controls. Any tips would be helpful. |
| Probable failure in standby power supply or source to mpu and associated circuits. Probable open fuse device to standy supply or defective regulator ic. |
| If this has a switching power supply, check for a 100uf/10volt cap on the hot side of the standby transformer, and I think, C805 220uf/50 volt cap on the secondary(-30volt filter for the "earom". If it does not, check for a 100uf/160 volt filter in the standby circuit. |
| QUESTION NO. P610-5: How do you enter the service mode on Sharp TV model 21R-SC ? |
| Hold volume up and channel up buttons in while plugging set into to power. Tv comes up then in service mode. channel up/down selects register volume up/down selects parametre's value. Register numbers have an 'S' preceeding them, data will be expressed in hex code. See June's issue of 'Electronics Service & Technology' Magazine or Sharp service material. |
| QUESTION NO. P526-10: I have a video problem with a Sanyo 28" Color. Model 82C952U (Canada).This set is distributed by Sears Canada Problem: Intermittant video,with slight vertical compression top and bottom,only when video problem is present.OSD ok.I suspect a component(capacitive or resistive)around IC101 (LA7655N).I have not been able to isolate this problem with cold spray or heat. Any suggestions? Model may also be listed as 14231. |
| Does the supply voltages to the ic change with the presence of video?? Scope the drive signal with no signal and with standard video input. |
| QUESTION NO. P68-9: I am working on a sony kv-2162m9 tv. It works fine for about 30 sec, then the horizontal transitor or d613 blows. Just before crashing there is a arcing sound from the power supply area.Could it be the PS transformer - t602? I have ruled out the yoke and H.V. transformer. |
| Arcing sound from power supply destroying the Horiz output? Suspect the flyback, crt, crt socket, and other hv related components. Excessive current is destroying the Horiz output. This is being caused by the arc you hear. The voltage in the B+ power supply in normally not high enough to cause an arc. |
| QUESTION NO. P610-2: I have 2-KV-27V55 (chassis SCC-F84H-A) in for repair. After replacing Q601, Q602 & r607, they failed again in less than a minute. Horiz out x-sist is ok. Can someone would share their troubleshooting procedure for this power supply? |
| First, use Sony original transistors for the choppers. Also, check for a thermistor in the secondary of the supply that ocasionally fails. Generally. replacing the two transistors and fuse resistor with original parts normally sufices. Once in a while the thermistor also causes a problem along with a leaky diode in the secondary. We have been repairing these sets in the field for some time with apx 98% completion rate. For troubleshooting, the use of generic transistors is fine but we always put Sony components into the sets before returning to service. |
| QUESTION NO. P64-2: I have an Emerson model TC2555D which no longer responds properly to the remote, or to the buttons on machine. Most noticeably, both the remote and the machine's power button mute the tv instead of turning it off. However, this is not the same muted state as triggered by the mute button, because the screen does not display the word "MUTE" in green. The mute button still produces the expected message, but many of the other controls no longer perform as they had. |
| Sticking buttons or defective MPU IC. |
| QUESTION NO. P64-1: Does the Toshiba Cinema Series 32" TV have a "Raster Rotation" (or equivalently named) adjustment from its service menu? |
| No. |
| QUESTION NO. P61-3: Toshiba CF2666R, chassis TAC 9102, circa 1991. I have a good pix, but the top four inches of raster has vert. retrace lines and Closed Caption data showing. The blanking bar is not visible, though. Sometimes foldover is visible, but not usually. Would this still be considered foldover? Caps in the vertical or the whole IC? |
| Suspect the electolytic caps in the vertical deflection and supply. Check with an ESR meter or, if one is not avail, subsitute the caps. |
| QUESTION NO. P54-1: I need a fly back number for a Sharp(model #19LP56). |
| The listed part # is RTRNF1445CEZZ. This crosses to most after market manufacturers. |
| QUESTION NO. P58-6: Does anyone know the values of RX3433 and RX3434 on a Zenith 9-1333-1 module.Model# SLS2549S? |
| Zenith 9-1335 which is very similar shows RX3433 as 15 ohms 1/2w and RX3434 as43 ohms 1w. |
| QUESTION NO. P528-8: Magnavox TV, Chassis # 25G1. Switched Mode power supply will not put out over ~ 55 volts. Have two sets w/ same problem. |
| Had the same problem. turned out to be IC400 Part# 483513097006. This is the optic-isolater in the power supply. |
| QUESTION NO. P527-8: NEC model ct-2750 27" ctv. powers up fine with a good picture and sound. after approx. 5 minutes vertical jailbars appear in the raster and the raster begins to dim. within 1 minute the raster is dark. |
| Check if the video processor ic in inserted in a socket on the main pcb. If it is, remove the IC, unsolder and throw away the socket, resolder the IC directly to the pcb. Have seen many strange problens in NEC basause of poor connections between the IC and socket. |
| QUESTION NO. P58-9: How do you identify wether a CRT is good or bad? |
| Does it arc when HV is applied or glow a pretty blue colour? Does the elements arc within the neck of the tube when the neck is lightly tapped [necessary to have the set turned on]? Is the definition of data displayed very crisp without any trailing colour or smear? Does the tube require longer than a 60 seconds to show any display? General functional checks plus the use of a good crt checker can certify your worries. |
| QUESTION NO. P514-4: Working on a Samsung TV\VCR Combo Model MVR-2100 TV
portion will not power up and gives out a constant capacitor charge "squeal"
from the high voltage section. VCR powers and functions normally using the RCA outputs. |
| P/S squeal indicates probable short in supplied circuits. Possible hv or audio problems. Deflection circuits take most current so check there first. Also check rectifiers and filters in ps specific to tv section. |
| QUESTION NO. P518-9: I have a Zenith SC3943W that will turn on but not turn off. It has to be unplugged to turn off. Suggestions? |
| Burnt contacts @ relay. Latching but not releasing due to remaninant voltage following attempted shut-down. Check relay contacts and diode paralleling coil. |
| QUESTION NO. P520-9: Sanyo DDS923019" COLOR TV has a vertical picture is 1/4 the normal size. After 10 minutes of operation the picture grows to fill the screen but it is distorted and there are small horizontal gaps. I have replace the virtical drive IC451 and Video Detector IC101. The problem is still there. |
| Check for dried electrolytic caps in the supply and actual deflection ckts. Also check for resistors that may have varied in value. Since it opens up during operation expect something that changes thermally or only with applied voltages. |
| QUESTION NO. P520-7: I have a Sharp TV model #25NV68(BK) that has no power. You can hear the relay click. Any one had this problem on a Sharp? |
| I have experienced a fair number of opens at transformers in the newer Sharp tvs. Standby more prevalant than driver and FBT but have seen all. Also, check the standy power supply for b+ when the relay is energized. |
| QUESTION NO. P514-6: Toshiba CF2655R, faint vertical retrace lines. I cannot get green bias down enough, blacks have greenish tint. Replaced a couple dozen electrolytic caps. Still retrace lines. |
| Check for burned bias resistors/pots or leaky green drive transistor on CRT board. |
| QUESTION NO. P514-9: How do I get into the service mode on a zenith se2795 system 3 didital set? I want to adjust greyscale. |
| Try pressing the menu button and hold until the menu disappears. Then, on the remote press 9,8,7,6 then enter. |
| QUESTION NO. P417-2: I have a Sony KV-2092 tv which intermittently loses the tuned station on some of its channel numbers. What should I suspect? |
| Check for bab solder on the IF Coils and also on the ground tabs around the IF circuit. You can also see the plugs that make the connection between the main and the IF Board. |
| QUESTION NO. P56-2: I am repairing a Samsung C11-6229T t.v. - No picture at all - suspect due to screen voltage (G2 from FBT) approx zero. |
| The CRT socket had arced inside and there was consequently a leakage to ground - forcing 'screen' voltage to near zero. |
| QUESTION NO. P54-6: A Zenith SSB796H brought in Dead, found (MOSFET) Qx3407 and a resistor off it's gate on the foil side of PCB burnt beyond recognition. Anyone have the values for the Mosfet and the resistor off it's gate? |
| Since there is obvious damage to the pcb, flash over, etc why don't you get a replacement module from Zenith and repair the set. Use the 9-XXXX-XX numbers found on the original, defective module to get the part number you need. Having such damage in the power supply probably means there is more damage further into the supply and associated circuits. |
| QUESTION NO. P416-9: I am currently facing a problem repairing Panasonic TC-21L10 CTV with the smps. The smps is working fine with no load connected but when the tv ckt is connect the smps o/p voltage drops to half what is required(12&24 normally). I have verified that there is no short in the rest of tv circuit and same thing happens even if I connect a 100ma load at o/p |
| Replace the main switching transistor 2sc4804a with the same thing. This problem of load might have occured due to power surge/lighiting. It is little diffucuilt to remove the heatsink from the transistor so be careful. |
| QUESTION NO. P415-9: I am working on a rca tx826tb tv that is dead. tf01 vert shutdown was shorted and rf01 and rf 13 was open. also pin 20 of ir01 is missing the standby voltage. is there a way to defeat this shut down circuit? |
| Lift one leg of dx01 and dx02 to defeat the xray protect shutdown mode. |
| QUESTION NO. P416-8: I am working on a Mitsubishi CS-3103C T.V. The set cannot receive channels 2-28. 29-63 (last cable channel) are all fine. |
| Check for brown resin glue on the foil side of the signal PCB....especially @ the band-switching IC (LA7911). If no glue..try replacing the LA7911. Last resort...replace the tuner itself. |
| QUESTION NO. P416-3: I am working on a Toshiba CF2750K, the vertical output IC (AN5521, IC301) shorted which blew the fusible resistor R327. I have replaced both of these and now have a picture, however, the picture is not centered, it has a 1/2 inch band accross the top and the channel number, etc. are right at the bottom of the screen. All voltages and waveforms feeding the vertical yoke look good. Any ideas? |
| On most older toshiba tv's there are 2 caps that always cause vertical problems: C301 & C305 both are 2.2uF/50V HIGH TEMP! and are usually RED in color. |
| QUESTION NO. P42-8: I have a Magnavox with a shorted HOT the no. CSD 1555 does anyone have any spec's on this part ? I can't seem to find out any info. on it. Set Mod. HD1906 C121 Chassis 19P615-ooAA. |
| I checked philips service manual for this unit and the HOT part # is 4835 130
47897 which crosses to an ECG 2353 NPN horiz output with damper diode. |
| QUESTION NO. P415-10: Sony KV-32XBR35 - no power - blown F602, R623. Any advice? |
| Check both switching transistors in smps circuit, check horiz. output transistor. Normally the smps switches short and open the fusable resistor. Replacing them may get this unit operational, however, if the horizontal output also is shorted you may have a defect in the fbt or deflection circuits or derived supplies. |
| QUESTION NO. P47-9: I am working on a rca f35100st ctc169. I have replaced q4101 u4101,jw340,and r4001 because of the dead set problem. After replacing these parts the set comes on. after a few hours q4101,r4001 and u4101 are shorted or open. Can any body tell the what is causing these things to short? |
| I just had this one! Replace the parts you did before to get the set to come on again. Plug the set in and keep it in standby mode. Measure the base voltage on Q4101 (SMPS power transistor) and it should be about -0.2VDC. When you turn the set on, I found it dropped to about -1.2VDC (reference to ground). If it's more positive than this, or if the transistor is *forward* biased, it will run *very* hot. In this case, check for a 3.0V zener CR4122 and capacitor C4108. Change both of these and your problems should be solved. (don't bother testing the cap, just replace with a 105 degree cap). If the base voltages are normal, check the "snubber network" C4111, C4112, CR4105, and R4119. Also check solder on L4101. I would also change the 'lytics around U4101 (SMPS IC). When you're done, Q4101 should not be too hot to touch after running for several hours, although it does run very warm. |
| QUESTION NO. P42-9: I am trying to repair a Sony Model KV-1882AEB (chasiis SCC-573A-A) This set has a prgrammable tuner. It appears to program ok but once power is removed the tuner loses its programmed channels. I was under the impression that a battery held the memory after power was off, but can not find any battery on the schematic. I have a feeling the problem is a bad CX7959 Sony Memory chip. Can anyone give me some thoughts on this problem also need a current address/ telephone # for the Sony westcoast Parts center. |
| Yes. Your problem is most likely the memory ic cx7959. As for west coast distributor Sony has a service/training center in Costa Mesa Calif.I do not have the telephone number however I suggest calling 1-800-555-1212 directory assistance for an 800 Sony listing and go from there. |
| QUESTION NO. P46-9: Toshiba 27in tv hit by power surge cx2668 tac8812 replaced c840 and c841 and 5volt regulator trip relay have high voltage but can only get less than 3volts out of 5volt regulator L78M05. Any ideas? |
| Start by unsoldering the output pin of L78M05 from pad. If the 3v doesn't come up to 5v with no load then the regulator is bad. If the output leg does come up to 5v then you have excessive load on the regulator pulling it down to 3v. There is no easy way to locate the load except to resolder the output pin of 5v reg. and trace every branch the 5v goes to and one by one unsolder that branch or ic pin from trace and see if 5v comes up if not resolder and go to another branch.Soon you will locate the defect. My suspicion is that it will be a bad ic. |
| QUESTION NO. P47-8: I am working on a rca f35100st ctc169.i have replaced q4101 u4101,jw340,and r4001 because of the dead set problem.after replacing these parts the set comes on. after a few hours q4101,r4001 and u4101 are shorted or open can any body tell the what is causing these things to short. |
| Replace Q4101,U4101,R4001 again if bad. Then also check or replace CR4122 and R4110. |
| QUESTION NO. P42-7: I am working on a Toshiba, Model # DA1766m-01 which only displays a white "Vertical" line; Yes Vertical. I found Q7630 shorted and replaced it only to have the exact symptom. I have no schematics and suspect that a fusible resistor or another component may have opened when Q7630 shorted. Has anyone had this problem and if so could you help? |
| Check for an open cap, resistor, solder joint etc. in the yoke vertical circuit. |
| QUESTION NO. P41-5: Does anyone know how to get into the service mode of a Sony KV-T29MN81? |
| Check for a small hole on the back panel of your tv. Puch a non-conductive device thru that hole and press select switch to activate service mode. |
| QUESTION NO. P330-3: I have a Sony TV model # KV-32S25 which came in dead. I replaced Q601, Q602, R607, in power supply and Q502 (horizontal output). The set now powers on but has no high voltage, sound and tuner functions ok. The high voltage seems to pulse on for a few seconds then disappears. |
| HV Protect or B+ is going to high causing HV shutdown. Have you tried disconnecting the hv from the crt & seeing if shutdown occurs then? Carefully PLEASE! May even be a fault in FBT. |
| QUESTION NO. P41-9: I understand Craig Consumer Electronics is out of business. Does anyone know where tv parts may be obtained? |
| Locate the FCC data from the rear panel. Check the FCC mfgr data base to locate who the original supplier was. Then, hopefully they may be able to supply necessary parts if set is not to old. Many brand name suppliers used another marketing name to sell their products, i.e zenith/ admiral/ bell & howell, etc. |
| QUESTION NO. P42-6: I am working on toshiba 27 tv cx2668 set will not turn on, hit by power surge the 5volt regulator has only 3 volts coming out. I have replaced it and also c840 and c841. Any ideas why I cannot get the 5volt regulator ic back to 5volts. |
| Does the +5 reg run hot. Seems as if you may have excessive load on the 5 volt buss?? Hit by power surge it may have sustained unusual damage. |
| QUESTION NO. P42-2: Panasonic CTK 2042R(other models too)sam 2694.Out of focus for the first minutes, some times more.After that works ok.Checked crt,crt socket and board,solder connection of focus lead,flyback,res.and caps.at pin 3(abl)of fbt,c565-npcap.Were is the problem in these sets? |
| Possible humidity problem with crt socket or problem with source [FBT]. Have you used a HV probe to monitor the Focus and HV for the first few min when the set is first powered up?/ Also check the regulated B+. Slow warmup of the crt may also cause similar symptom. |
| QUESTION NO. P318-5: Need RCA part# or equiv. for t4100 Viper Transformer in 27" tv model f27100ak, ctc140 board location T4100. |
| RCA,GE,PROSCAN CTC-XXX all have chassis families for a given chassis. They are indicated by the letters following the chassis number. Since your question didn't have trailing letters on the chassis This answer assumes no letters. For CTC- 140 with no letters and all the following 140, 140AC,140AE,140B,140C,140E T4100 Vipur Output RCA part# 179723 the writing on top of transformer for this series should be 2847401-502(1) You can also see SAMS manual # 2608-2. If this reply doesn't satisfy your requirements then resubmit the question with the trailing letters of chassis and I will ll be glad to research it for you. |
| QUESTION NO. P323-1: Sylvania t.v. model rkj 178 wa02 powers up o.k. but will not tune to any channels. There is just static on screen and out of speaker. |
| Check r321 10 ohm 1/4 w resistor. It feeds the +13v to the tuner. |
| QUESTION NO. P326-10: I have a RCA chassis CTC175 with the three tic, dead set problem. I went to my distributor to buy the "Chipper Check"PC Interface box and software which will check for defective IC's on the bus line. I got the interface but was told that they could not give me the software unless I was an authorized service center. Is there another source for this software, or am I just stuck With a $100 pc interface that I cannot use? I have contacted Thompson and they tell me the same thing. Please help! |
| The servicer can purchase the software direct from TCE Publications, 10003
Bunsen Way, Louisville, KY 40299, Phone: 502 491-8110. If they encounter any problem or
have any questions regarding "Chipper Check" they can call our Help line at 800
711-6913. NOTE FROM WEBMASTER: There was an answer posted here that was contrary to the above information. The manager of the Chipper Checker at TCE contacted us and provided the above correction. We regret the mis-information that was submitted to us and posted here. |
| The "chippercheck" will not allow you to check i.c's on the buss of a ctc175 chassis. It is for tuner alignment only on this set. |
| QUESTION NO. P323-7: I am working on a Sony kv27ts32 q601, q602 pwr conv are shorted r607 and r644 are open. replaced same parts and transistors shorted and resistors opened. has anyone encounted this problem and its cause. |
| Use original SONY PARTS. Check the Horizontal Output Transistor, if shorted you may also need a flyback. Also check for defective parts in secondary of main smps. |
| I had the same thing happen on an XBR version. Turned ou to be a shorted primary for the standby transformer( small xformer just forward of the 2 transistors) |
| QUESTION NO. P324-9: Could you please tell me the ratings of the 2SD1555 horizontal output transistor(particularly V ebo)? Iam using NTE2331 in a Magnavox RX4476 AK06(25N101-00E) and base voltage as well as J-test4 voltage and regulators are ok. The transistor heats up to over 52 degrees celcius after about 15 minutes of operation. Also, what is the inductance value of the Philips 3620-0028-0015 horizontal linearity coil I measured about 21uH? Vertical and horizontal deflection yoke resistances are 7.4ohms and 1.4ohms respectively vs. the 7.8/1.8 listed in the schematic, but both appear to be unimpaired. When the horizontal yoke is out of line transistor heats up to an acceptable temperature, which leads me to beleive that the problem is isolated to the horizontal deflection coil or associated components. Could you offer any suggestions on how to remedy this situation? |
| 2SD1555:: Vcbo=1500; Vceo=600; Ic=3.5A; Pc=50W;Icbo=~10ua@500Vcb; Hfe=~8; Basing BCE with [2-16E3a] type case. The overheating of this component may be caused by incorrect waveform from drive circuit or defects in the ringing capacitors &/or coils in the horiz deflection circuit. Don't rule out the flyback or components in the derived power circuits powered from the flyback. |
| QUESTION NO. P35-1: I have an older Sony tv mod# kv-1710 problem: 2-3 inches from the bottom of screen has lost its picture! Any specific capicitor I should be looking for? Could it also be another component? |
| KV-1710, if there is an ESR Meter available you may check all of the capacitors in the vertical, derived, and main ps. Not having access to an ESR Metre, and from the age of your tv, it may be to your advantage to replace each of the electrolytic capacitors in the said circuits, esp the vertical supply and deflection. Also, check the bias voltages on the active devices in the vertical circuits, some of the resistance values may also have changed or the transistors may become leaky. I.E conduct lower than design spec. |
| QUESTION NO. P318-10: I have an RCA 19" Chassis# CTC-175A. The set came in with no On Screen Graphics. I soldered the usual grounds under shield and replaced the EPROM, T-Chip, CPU. The voltages seem to be normal. Pin 8 on Eprom has nominal 5v. Pins 5 and 6 have around 3volts each. I even tried a second new EPROM. |
| Replacing and programming the E-Proms are two seperate things. Did you reprogram the data into the E-Prom or does the set still refuse to initialize? Assuming the data in the E-Prom is correct, suspect power supply & or deflection problems. I'v even found shorted dampers and components that were never corectly soldered to the pcb. |
| QUESTION NO. P318-8: 1989 Zenith 25" console w/Remote. Model SE2507N. No apparent Chassis NO. Set has five seperate modules. Main-module on floor(# 9-516) pwr-supply on right, tuner/Display interface on left, Video interface on plug of Pix tube. No-pix, no-hi volt. Has distorted sound, can control volume with remote, can change channels w/remote. All fuses good, no visual component failure. Help! |
| 9-516 still avail from mfgr. Good place to start since it has most of the deflection & ps circuits. Check Horiz output for shorts, check B+ @ main filter caps & horiz driver collector. Make sure CRT is good before spending much time or parts on 89. |
| QUESTION NO. P318-7: I have a Zenith TV model SS6509G that was the victim of a power surge. R3296 was blown apart, unable to find a replacement part number. |
| Find the little white tag, order the 9-XXXX-XX part number, and replace the module. Who knows what else was fried from the power surge. Check quality of CRT also before going too far. |
| QUESTION NO. P318-6: Magnavox RJ8530AK03 Projection TV. The problem is with the convergence drifting slightly out of adjustment all the time. For the most part you can make adjustments from the On Screen Display but it changes over the course of a few hours. I also have to break out the pattern generator every few weeks to make more major adjustments. The convergence board has been replaced once and is still relatively new. Am I missing something here? Also, I can't find a manual for this TV. Can someone help me find the values for resistors R53,54,55 on the power module board. |
| Let's see, from the back there should be two boards @ the vertical panel. Right power, left deflection. A problem with changing voltage supplied from either to the dynamic convergence panel will cause drifting. I've had better luck in just replacing both the PS & Defl panels or at least trying them with good [new] subsitute modules. Expensive !!The print should still be avail from NAP but maybe only on fische, better than nothing. Also, if you haven't already check the condition of the coolant fluid in the chambers @ each crt. Probably needs changing to get rid of bacterial growth that will cloud the fluid [looks like floaters]. |
| QUESTION NO. P318-1: I am working on a Emerson TV, model TC1365B suffix L. It is dead. I have checked Sam's and cannot find schematics for it. The 115 vac primary fuse is good and the 6 vdc regulator has nothing on it's input leg. |
| Check for B+ @ the large filter caps in the main power supply, if there then advance to the regulator [ic]. Check the horiz output for shorts. Advance logically from power to sweep circuits checking for probable shorted or open components. Check high wattage resistors in both main and derived supplies. |
| QUESTION NO. P317-4: I have a Zenith model SlS 25535 that has a no power condition. Main and lo power supply fuses good. rx3433 burned. No apparent cold solder jointsor other damage 9324 diode in area shorted- now replaced. What is value ofrx 3433? any ideas on no power(startup)? |
| Suggest checking the CRT. Some of the SL models have crt failures that also damage the main modules. Check the crt with a good module or better yet, with a crt checker. Specifically check for inter-element shorts. |
| QUESTION NO. P317-3: I am working on a Zenith SLS2555S - after about 20 minutes picture gets very dark with barely visible blue. Turn G2 control down and back up and its good for another 20 minutes. Focus Volts vary from 690(working) to 410 (dark). G2 @ 7kv (constant). Any idea if it's the tube or flyback? |
| Probably the fbt, suggest trying another known good module or a CRT checker if available. Tap lightly on crt neck while viewing pix. If brightness changes while taping on crt or if there are flashes in the picture or physically within the crt neck then you know what's causing the problem. |
| QUESTION NO. P310-9: Zenith Model SD2511, After customer replaced power supply brd, audio does not come up right away, takes several minutes like something is heating up. Audio into output chips looks good. Voltage on input pins is low as if the limiter is affecting it. Only the 7 volt source is low ( 6 volts ). |
| Suggest checking ALL CABLES for proper hookup. Also try another known good P/S board. Heafty estimate including new autio module [if still avail] and audio interface module, mts-stereo decoder. Highly recommend looking for something stupid, like wires pulled from connectors, reversed or crossed cables, some do look alike. |
| QUESTION NO. P211-3: I have a Magnavox model RJ5540 AK01 TV (27G1-01 chassis) that came in with C502 fried as a result of a HOT with a leaky base-emitter junction, I believe. Could someone please give me specs of this disk bypass capacitor? |
| Use a 1.5kv/471pF polyurethane disk cap & replace the HOT. |
| QUESTION NO. P36-1: RCA TV, model F35751MB CTC169BG5 Vertical High and corner words lose (PIN CUSHION PROBLEM). Do you have procedure for imput to eeprom configuration? |
| Change the Pin Damper diode and associated cap [ usually .056 ]. You will find the cap slightly swelled due to internal pressure. Common 169 problem. Don't worry about E-Prom data until you see 175+ chassis. |
| QUESTION NO. P35-9: I have a Sharp 19" television that someone has been into. There is a part missing and I do not have a schematic. The model is 19LP16 and the location of the part is SCR701. |
| Sams lists sveral originaql part numbers but they all cross to ecg5457. |
| QUESTION NO. P225-10: Having difficulty with Magnavox 27T1. Unit does not lock on channel immediately. Requires 3 or 4 searches then continues to tick after pic is on. Have replaced aft coil & S.A.W. filter. Aft coil has no effect on pic. Unit has taken a lightning surge. |
| Anything from the RF input to the processor chip. Blitz usually destroys items that are not usual failures so assume every component in signal selection and processing may have sustained damage. Usually just rocking the aft adjustment will allow proper lock but after lightning anything goes. |
| QUESTION NO. P225-6: I have a Zenith SE 5221W (1989). Sound, no image. The tube is cold. High voltage circuits are evidently working (noise). Without an electrical daigram do not know how to approach the repair. Any suggestions? |
| Cold CRT? I assume that you mean the filaments are not lite? Confirm that the HV is functioning with a neon [ne2h] bulb attached to a non-conductive rod or stick. The bulb will light when brought near the flyback core windings. Asuming the hv is operating then check the connections on the CRT board, filament leads, and the connections on the module. If all else fails order the 9-XXXX module fron\m Zenith and repair the set. Of course, the filaments in the CRT may be open but highly unlikely. |
| QUESTION NO. P220-8: I have an RCA (ctc177) with a kind of degauss problem. The bottom right and left of screen are not well. At first, the tv was not working and I resolved the problem by replacing the STK730-010 (u4101) regulator. Can you help me? |
| Is it possible the tube was jarred or bounced shaking the shadow mask?? Sounds as if you may want to try some spot magnets. All the purity & convergence adj are done by the magic ring around the neck. New tube time possible. |
| QUESTION NO. P224-7: Magnavox TV Model RP2786-B904, about 5 yrs old. Has significant vertical overscan problem, and I desire to adjust vertical size. I'm not in the TV business and don't have access to TV service menu codes in other manuals. FAQs tell me how to enter service menu, but I am presented with a large matrix of un-labeled codes ranging from A:0-28 to D:0-28, each with a hex adjustment value. Any help identifying the right one? |
| NAP in Greenville Tenn will gladly supply info to qualified service companies and technicians. |
| QUESTION NO. P224-3: I am working on a Toshiba 27" TV model # CF2666A with chassis # TAC 9100. The set has no vertical deflection with the picture squeezed to a thin line in the center of the screen. I feel the problem is in a bad cap on vertical height board but I am unable to locate which cap it is. Do you have any information as to the likely problem? |
| Suspect either the vert output ic or the supply sources to the ic from the sweep ps. The caps may result in foldover or distorted sweep but rarely cause total failure. |
| QUESTION NO. P23-7: TV Emerson Model M1375RA - No raster or sound. HOT no pulse but has DC Voltage 130V, DC from power (5V Reg.) good. No DC voltages from flyback. Startup problem? I cannot find signal that would get things going. |
| On several of these we have found IC301 bad. AN5156k. |
| QUESTION NO. P128-1: I am working on a Sylvania 26" set which exhibits the problem of the H.O.T shorting out after replacement. The set will run fine for a day or so. I have resoldered T501 the horizontal drive transformer. I am also using an NTE replacement for the H.O.T. Should I use only an original NAP part or do I have trouble else where? |
| Remove the horizontal drive transformer, sand its conections and then reinstall it. Tap on top. If this effects the horzontal then the top connections are bad. They do not solder very well and you must replace. The number is on top, Put 361xxx in front of number. |
| QUESTION NO. P216-9: I have an RCA 25" stereo tv, model F25652BL, chassis CTC187AB. The set is 4 years old. Initial problem - Picture pulled in from top & bottom, static in picture. Tapping or cycling power would sometimes clear up problem. Set finally quit. Replaced HOT, set worked for about a week, then symptoms returned, and then HOT went out again. Understand this is a common problem with RCA / GE sets, but have not found solution yet. |
| See www.paranoia.com/~filipg/ look under Sci.Electronics.Repair Faq for RCA/GE CTC 175/176/177 and follow reccommended repairs. It is also probable you have by now blown the E-prom in the set. If all else fails take the set to an authorized RCA repair shop. |
| QUESTION NO. P29-7: Mitsubishi CS27200 has about 1" of information around edge of screen and black in the center. |
| Turn off the Closed-Caption mode thru the Video settings via remote. It is probably set to "TEXT 4". Using the remote control: press >video< button until "cc:text" appears, press >adjust< button until "cc:off" appears. |
| QUESTION NO. P114-1: I am working on a RCA CTC-149 that the Horizontal scan is about 4 inches to wide. All other circuits are working. |
| If there is a blue rectangular capacitor or grey off the collector of the H. O. transistor. Change it if it is bulged out on the side. |
| QUESTION NO. P29-4: I have a megatron t.v. model# ctv-1371(e) thats channels up constantly without the press of buttons. It has a i.c. chip in it that I believe controls the channel functions. It is a mn15287hy. I do not have any specs on it. can anyone tell me which pins control the channel up, or has anyone seen this problem before? |
| I would first look for any jammed push buttons on the front panel. This will cause a in-key command to the mpu. This may be caused by debris around the button or a failure of the actual switch. Check them with a meter to confirm function. Any low/high at the switch inputs to the mpu may be causing constant scan, shorted caps etc attached to the ic. Look for the oblivious rathen than comdeming the mpu. You should be able to trace the paths from the buttons to the pins of the mpu. A good magnifier may help. |
| QUESTION NO. P25-3: How do you change the colour settings on the Goldstar 1715SS? There are no pots. Presumably it is done with software. Is it likely to be available? |
| Assume you are asking about customer's settings and not tracking? With original remote and G/S access code found in tech manuals you may change tracking [bias, etc.]. Customer's settings via on-screen menu in picture settings. |
| QUESTION NO. P25-9: Zenith SF2507N - Pix is dark, narrow & short with vert foldover when powered-up. increasingthe consumer picture level causes pix to shrink & start to shut down. Also any program with a white background causes the same. The problem gets better as the unit warms-up indicating an electrolytic cap is involved. However, I do not speak Zenith very well. Any direction would help. |
| Find the little white tag on the main board. It will be 9-XXXX-XX. Order a new board from Zenith & replace the one you have. The joy of finding out what is wrong with the original pcb may be outweighed by the ability to complete the service with a RMA board from Zenith. |
| QUESTION NO. P22-11: Troubleshooting Toshiba 26" TV, Model # CF2665K. No Sound. Having difficulty locating fault. I cannot switch from 'SPKR OFF" to "SPKR ON". Don't have remote but, front panel controls include: SPKR, CATV, VID, Rest, FUNCT, VOL UP, VOL DN, CH UP, CH DN. I get SPKR OFF always whenever I press Spkr. Switch. |
| May be op error. Could be defect in mpu. Suggest getting original remote and try changing parameters then. The setings change on some Toshib sets when you access the function without pressing select buttons. However it is much easier with the proper remote. Have had many customers not able to stop 'demo' mode because of fact when change is accessed it may be comitted without manually selecting desired change. I.E. when you go to item in menu you actually make a change in it's setting. I know, clear as mud. |
| QUESTION NO. P24-7: I am working on a 27" RCA ctc169 chasis, model#f27188bt.The original problem was a dead set condition caused by a shorted cr4101.After replacing the diode the set powered up ok and the video was good except for overscanning in the horizontal.Both sides of the picture are cut off.I tried to adjust the horizontal width pot but it had no effect.Is there a service menu I must access to adjust paramiters in an e-prom like the ctc177 chassis? |
| ANSWER 1: Excessive width usually caused by shorted PCC Diode (use ECG577) & Yoke return cap...either .047uF/400v or .056uF/400V. (Square,blue or grey plastic case) This cap is next to the PCC diode & MUST be replaced at the same time. |
| ANSWER 2: Sounds as if the pin damper diode and associated capacitor aprobably damaged. Diode is physically located in front of horiz output. Cap is a .056uf or similar in value. Cap may appear slightly swelled. Common failure that can destroy hot transistor. |
| QUESTION NO. P126-10: I am tying to fix a Sony KV-C27TD that blew up by a thunder. Surprisingly no filter nor fuse destroyed on the F1 board. The Q602 and IC601 were off along with a track near R614. Unfortunately after replacing these plus all capacitors around IC601 and transformer T601 no AC is detected on the secondary of T601. There is 360VDC on C604 but pin 16 of the IC 601 has only 7.6VDC instead of 9.4VDC. Please give me clue ! |
| After being blitzed only God knows for sure. Get a good schematic from Sony and check each component in the standby power supply circuit. This is the starting point!! Check for any high wattage [i.e. over 3 watt]components being blown open. Any of the capacitors in the supply could have had the interior pierced by high voltage spikes. The main problem with lightning & power surges is that they do damage to items that usually do not fail in normal operations. Not being cruel the sky is the limit, you may very well get the set operating to find out 3, 6, or 9 months from now other components failing because of the severe stress. |
| QUESTION NO. P128-3: I have a sony tv KV-19TR20. when cold has raster with no picture. works fine when hot. |
| Does the audio go away also? Possible the grounds within the tuner or possible poor solder connectiona around tuner/if or at regulators on board. |
| QUESTION NO. P129-2: I have a Sylvania Model # SPA 4756 which has some intermittent read smear usually on the face of an actor. Also I have noticed that during some sceans the CRT is very dark where others are near normal. I do have a Photo Fact for the set, but am not sure where to concentrate. I.E replace the signal processor or whatever or could the CRT be on its way out. |
| It is probable the crt has seen better days. Check it with a tester if available. Be sure to check G2 & G1 bias voltages before condemming crt totally. |
| QUESTION NO. P126-3: I have a Sharp TV model # 19RP59 that shows no color. The color osc show 3.58087 mhz, which is too high. The trim cap (c809)works out of circuit, but adjusting it in circuit caused no change in freq. I have replaced the crystal. Any ideas? |
| Check other components connected to the video processor ic. May need to change procesor ic. Confirm proper voltages at chip. |
| QUESTION NO. P127-4: I am working on a symphonic tv model 13tvcr MKII. I inadvertently moved the triads color adjustments on back of the picture tube (6of em) and now I can't get a decent picture back. when I try to adjust the color the focus gets bad and vice-versa. Is there a certain process or any special equipment I need to do this? |
| Assumption is that you have mis-aligned the convergence & purity ring magnets around the neck of the crt. Suggest going to libraty and getting a book on TV repair and atempt to realign those magnets per information in purity static convergence section or the books. Be advised, it may take a bit of time and develop your patience. Also you may try degaussing the tv before doing anything. You do not want any speakers or loose magnetic materials around the tv while doing these adjustments, i.e. other than those designed into the set. |
| QUESTION NO. P115-5: Philips TV,chassis #27c9-03 Problem: After 5min of warm-up, herringbone pattern in picture plus an intermittant jitter.I suspect IC 201. |
| Possibly thermal changes in SAW filter components. Try tweaking coils near SAW/IF. If no help you may try cooling coils and changing those thermally sensative. |
| QUESTION NO. P119-6: I am working on a JVC AV-2750S with no raster/audio (only thing I hear is the relay). The unit may have been A/C spiked. Can't get the sch. from OEM or Photofacts. Any suggestions on what I should look at first? |
| Check +9 volt regulator P/N BA17809T |
| QUESTION NO. P120-5: I have a Magnavox RR1933 W422 tv with a vertical deflection problem. It has a horizontal line across the screen. The audio is fine. I checked the supply voltage (24VDC) to the vertical deflection IC and it was fine. I also tried replacing the vertical deflection ic and checked capacitors nearby. The line is still there. |
| You did not state if the bias voltages were proper at the ic or not. Probable the source isnot getting to this ic. Also check continuity of yoke windings and circuit components from ic to yoke inclusive of caps and resistors. |
| I checked the vertical ic inputs on this unit. Replacing M52030ASP (4835-2098-8106) solved the problem. This ic is available from MAT Electronics for $3.95. |
| QUESTION NO. P119-1: Can someone please supply me with the pin out configuration and voltages of MPU IC on a Magnavox 25n1-01 chassis. I'm trying to fix a dead set and I need to check the data pulses and supply voltages. |
| Philips part # for CPU for 25N1 chassis is 4835 209 87551 pins 1,3-6 customer controls (color, tint, etc) pin 2 volume control .o1-3.8 volts pin 9 aft 2.5 volts, 3 with no signal pins 10-13 key board input 10- 5 volts 11- .09 volts 12- 5 volts 13- 4.3 volts pin 14 coin. i volt no sig, 4.3 with pin 33 reset 5 volts pin 37 clock .03 volts pin 38 c-enable .03 volts pin 39 scl .07 volts pin 40 sda 5 volts pin 19 power on/off .09 on 35 IR input 31-32 Xtal 2.6 volts high side |
| QUESTION NO. P17-3: I have a RCA VR250. When plugged in the red led for power comes on. the display does not illuminate. I replace three leaky electrolytic caps(2 740 mF and one 2200 mF). Unit still exhibits the same problem. Is the 15volt test point on the supply sufficient to declare the supply good? |
| I had the same problem with a VR450. A shorted cap C874 1uf@50 volt. was the problem. |
| QUESTION NO. P116-9: How do you perform the tuner alignment procedure on a CTC 175a chassis? I had a bad eeprom (dead set) and I wasn't able to record any values. The only thing that is left to do is realign the tuner. Do I need a special alignment generator or what? |
| See http://www.elmswood.guernsey.net/ctc177.html. |
| QUESTION NO. P114-7: I Have a Toshiba CF2010j with a vertical deflection problem. The bottom Half is black and the top half has some kind of linearity problem or foldover. I have replaced the signal processing and the output driver with no repair. |
| To repair this problem you must replace two red capacitors.One is located inside the shield for the deflection IC. The other is in the vert. output ckt. |
| QUESTION NO. P114-10: Zenith SLS2549S with single horizontal white line. Similar to q P325-3. Should I replace RX3209 or resolder my Vertical IC connections? |
| Yes, also chesk the diodes around the vertical output device and supply B+ to it. If that fails find the 9-XXXX number on the module and replace it as a complete unit. |
| QUESTION NO. P18-4: I have a Magnavox M# RG4550 AK02 C# 26C813. It will not come on at all. I am getting Power all over the main board. But when I push the power button nothing happens. |
| Check for voltage at the mpu ic. Check for osc function at mpu ic, check for data input and output at mpu ic. Check for voltage at power relay coil terminals. Check for data input from in-key presses and from remote reciever. Check for +5 v or +9v at remote reciever. |
| QUESTION NO. P16-8: I am working on a Sony KV1998R. All the channels that are programmed in to memory have been lost. I can manually tune in to the channels, but I cannot "surf" through the channels. I have tried adding them back in to memory but they just keep disappearing. |
| Possible defect in memory ic or loss of supply to same or mpu. |
| QUESTION NO. P16-5: Am working on a Phillips chassis 26C614 that is in a Montgomery Wards TV. My problem is that I have raster and sound but when I hook up cable or ant. there is no picture or audio. Also cannot program channels. |
| Probable bad tuner, mpu, or memory ic. Check all voltages at tuner assembly. Check for communication data to/from tuner. Check for data communication to/from mpu. Highly suspect tuner or bad connections, lack of data transfer. |
| QUESTION NO. P16-4: I am working on a 25" Zenith stereo color TV Model SMS2553S. The problem seems to be in the tuning of the set. None of the cable channels (nor the broadcast channels) are being tuned in on frequency. It seems that the set could use fine tuning adjustment! I have tried with the "Auto tuning" setting in both "fixed" and "search". There is no noticeable difference in the performance. However the TV works okay with the camcorder (both CH 3 & 4) and the Nintendo RF input. Any clues? |
| Find the little white tag on the signal board. Order the replacement module [ 9-XXXX ] from Zenith. Install part and cure problem. Trying to trouble-shoot usualy cost more tham replacement. Note: replacement modules have been running aproximately 80% reliable. |
| QUESTION NO. P17-4: I have an older Zenith model C5556G with what I believe to be possibly a bad CRT. The set will intermittently turn the entire screen red, then shut down and come back on at channel 2. Once, the set was down for a couple hours with a red screen and would not come back up. There is also noticable image shrinkage when there is a bright (white) background, and occasionally thin zigzag lines across the top and bottom 1/4 of the screen (also appears related to image brightness). Pincushion also appears drastically different at different image brightness levels. |
| Yup, Bite the bullet, you describe classic failure of a shorted crt, red gun. |
| QUESTION NO. P17-2: Recently an RCA Mod# p46101wk, Ch# ptk169pua, Shut down ( Dead). An examination of the main board came up with a blown 5 amp fuse, an open r1v (an ac surge res. 1.8 ohm, 15w), the chopper trans. (Q4101 a B+ reg. # SGS 461 ), the I.C. u101 was replaced also replaced.. After power was applied the set came up with sound and the normal high voltage crackel was noted as well indicating it was present but no picture, guns were black. No video drive or somthing? |
| You did not state if HV stayed or if shutdown. If HV remains problem may be in G2, G1 supply or filament supply too. If HV shutsdown suspect HV splitter, common failure, or possible one of the tubes shorting, disconnect each HV lead from splitter & try operations. Also when chopper is blown usually replace the ps controller ic and check the diodes in the controller circuit. Intermittant shutdown or intermittant startup can be caused by CR4116, the +15 v supply diode. If Hot transistor is shorted change the Pin damper and associated capacitor, usually a .056 ufd or close in value. If cap is bad it usually swells a bit. |
| QUESTION NO. P1219-4: I have a Mitsubishi CK2604R Color TV that has sound and picture, good Vertical, but the Horiz size pulls in from the left and right when picture is bright. My 28KV HV only measures 18KV and of coarse all other voltages are low. The HV never gets high enough to shut its self of, I have check about every diode and resistor in the Horz circuit, everything points to the Fly back! It, however does not get hot. No way to tell if one or more of the HV diodes in the flyback are bad. |
| Try to check the scan derived voltages of the FTB. Try reading the filter capacitor. Most of it is operated 60 to 80 percent of the total voltage. If it is low your FBT does not receive enough voltage or there is something wrong with your FBT. Try adjusting the B+ of your PS then try to measure it in the B+ of FBT. There is a fusible resistor in between or a coil try to check it if its almost the same or try using a capacitance tester and measure all the capacitors in the HV section and horiz section. If these do not fix it try replacing the horiz IC or transistor. |
| QUESTION NO. P15-9: I have an EMERSON tv model TC1365A which keeps detuning and tuning in the station that it is on. In other words it will not lock in the channel that you have selected. I have changed the tuner, and the IC TA8680N but it stills persists. I assume it maybe the m/pro TMP47C634N, but have had no luck locating a supplier. |
| You will have to find an Emerson parts source for that specific MPU, If you are going to order it also get the memory ic. Before going that far check the small capacitors connected to the MPU and memory ic and those near the tuner. You may find some of then may be leaky causng the tuning problem. This has turned up in some Toshiba tvs also. |
| QUESTION NO. P15-8: I am working on a Magnavox 25N1-01 and I cannot get any relay action. The unit is completely dead with no fuses blown(F400/F401). HO, Bridge rec. check good. I've already replaced c411 as it showed signs of failure. The owner of the tv said that it had been hit by lightning and that he had heard a loud pop. |
| Check the standby power sources. Check for fried leads (you did say blitzed~). Check for voltages @ MPU IC. Check for data input to MPU via inkey or remote. Check for status changes @ power output pin of MPU. Check for bias voltages at on/off driver transistor. Check for apx 12 or more volts at coil terminals of relay. Must have standby to even attempt relay keying. Standy +5, +12, etc. |
| QUESTION NO. P128-6: I have an RCA TV CTC-131M. Chopper replaced several times. Lasts 1 mo. to 1 yr.... Set is now in shutdown mode and replacing chopper no longer works. Power supply will not start up with Horiz. Out. transistor removed. Replacing chopper turnoff and horiz output transistors did not help. Output from chopper oscillator IC appears to be normal & standby power ok. When set was working 129V was ok. |
| There is a RCA goldenrod bullitin #CTV-11 that will give you the fix for this problem. If I remember correctly there are two cercumstances that will cause this problem. RCA Part #829220 will cure the problem if the fault is caused by momentary interuptions of the AC power occur. |
| QUESTION NO. P1223-4: I am working on an RCA CTC175 which has no blue . I have replaced the color Ic. The is no voltage on the base of the blue output transistor. Don't have schematic and I am having a hard time tracing. Any suggestion? |
| ANSWER 1: You say there is no ( 0 ) voltage at the base of the blue output. There could be some bias there unless the devices to the transistor are missing or broken or the pcb is physically broken. Even if the transistor were shorted b to e there would be some voltage there with reference to ground. I would remove the trensistor then check for voltages. If there no base voltages then look for other devices, damaged or broken pcb or open foils. Throwing parts at the set probably will not fix it without finding out why the missing bias is gone. Once this problem is solved I bet your blue returns. |
| ANSWER 2: Try switching the blue output with one of the other colors. If you still don't have the color blue then your problem is in the screen itself. |
| ANSWER3: You need to get an RCA manual. All adjustment are made via the hidden service menu. The 2 most common problems with the 175/176/177 are bad ground connections or the EEPROM. First you need to solder all grounds, including those under and around the tuner sheild. Check the adjustments for the blue background and drives next. If replacing the EEPROM becomes necessary, you need to record all of the present settings, before replacing. All tuner and I.F. setings are stored in the EEPROM also. Replacements are set with nominal values only. |
| Ref to ans #3, be careful. If you record the old settings and use those settings in the new eeprom, your problem may remain. The new eeproms factory settings need to be tweaked thru the service menu. ie., tuner allignments, horiz freq. vert. size , etc. It has been my experience that the eeproms fail due to corrupted data, not a failure of the chip itself. therefore, copying old eeprom data to the new eeprom will cause the trouble to remain if the eeprom is indeed the problem. |
| QUESTION NO. P1224-1: I have a Sanyo model AVM-2555 - 25 inch stereo color TV about 1 year old, The picture is perfect, but the sound is real fuzzy. With one exception. Channel 4's sound comes in perfectly in SAP mode. All other channels produce audio that is low in volume and distorted/static low crackling noise as if the speakers were blown. When using the external audio outputs and running them to a stereo amp, the same distorion is present. Any Ideas? |
| Sounds as if the audio MTS decoder circuit may be to blame. You did not say if audio from an external device inputed via avio was distorted. My guess it probably is not. I am not certian if the MTS is part of the tuner assembly on this model of if it is seperate. |
| QUESTION NO. P1216-4: I Am trying to fix a Magnavox 27" console model #25EM2824P, older TV about 1980, there is a single horizontal line in the middle of the screen, channels come in fine sound is good, any help ? The TV did this once before, it sat for about 3 months when it was turned on it worked for about a month then did the same thing, tried to let it sit again but the picture remained the single line this time. |
| Could be as simple as a bad solder on an electrolytic capacitor in the vertical circuit. If you move all the caps in vert circuit one-by-one and height changes, then this is your problem. |
| QUESTION NO. P1216-9: I have a Hitachi TS-3600 television, a quarter of there top screen is is not displayed any more. I believe one of the capacitors is not working any more. Am I correct? How do I check when its still on the circuit board. |
| Probably not. I've seen a Hitachi CT1912A with a similar problem. Turned out to be vert drive or output transistor - can't remember which. Check by hitting one at a time with freeze spray and check for any reaction in picture height. Not only is this the easiest check, but the transistor will test OK statically and will only exhibit slight crackling at the highest frequency if using an audio feeback oscillator transistor tester. |
| QUESTION NO. P1222-9: I am repairing a Sony KV27EXR20. When the power switch is pressed I can hear a relay 'click'. No display or audio. |
| ANSWER 1: Suggest checking the Horiz. output and audio output devices for probable shorts. Also look for probable solder cracks around any upright voltage regulator ics on the pcb. Check for the proper B+ voltages from the regulator, may also be the regulator ic. |
| ANSWER 2: Replace with original IC # STR-S6301**** DO NOT SUB TO STR-S6301A **** |
| QUESTION NO. P1222-3: I have a Magnovox TV Model RR1937 W122. When it is plugged in, it comes on with volume all the way up or nearly so. None of the buttons work, neither does the remote do anything. I cannot shut off the set, change channels, or change the volume. Checked test points for proper voltage, all OK. I think it might be the TMP47C634N-R402 IC, but I want to be relatively sure before changing it. Anything else to check first? |
| Suggest checking the data pins, clock pins, and bias pins on the MPU which you may have dome already. Pretty sure bet if the voltages to this ic check ok but you havn't data transfer. Also you may try another clock crystal. If the MPU is functioning there should be pulses at the clock and stobe pins and at the data lines when a command is requested (key press). |
| QUESTION NO. P1219-3: I have Quasar Model TP1920DW-1 Chasis ADC195 that does a half roll & flips with jitters. Have checked caps near vert ic & changed ic. |
| IC301 Sig processor AN5301NK. |
| QUESTION NO. P1125-8: I am working on a Phillips tv, multi-mode purchased in singapore model # 33FL1880/56r. The customer complained that the set was progressively harder to start ( on off sequences). the switching power supply is now dead. all the outputs are not shorted. the driver is not shorted. |
| have found that many electonic devices with your symptoms are due to faulty capacitors in the control stage of the SMPS. These caps are typically between 1uF and 100uF. Check/replace all of them. |
| QUESTION NO. P129-6: I have a Zenith 27" console, model #SM2726EZW (C10 chassis). An electrical surge took out the set. I replaced the main board(9-1408-01) ,but now when the set is turned on it will play a short time then fade to black. Is my problem likely the picture tube, or is there an eprom setup on the main board like in the RCA CTC 175-187 chassis's? Could someone help? |
| I would try another "new" circuit board before the crt. Have seen up to 20% failure in some of the "bew" zenith modules. |
| QUESTION NO. P1126-9: I have a zenith c-2 chassis which has audio. When I press power it goes into h-v shut down. Any suggestions? |
| Replace the entire module supplied by a Zenith Parts Distribrutor. The rebuilt modules are aproximately 80 % reliable so your chance of recieving a good one is pretty good. |
| QUESTION NO. P1111-1: Magnavox tv/vcr Model# cct192AT01 Switching power supply won't start. When we pull out the power supply fromthe tv. tv voltage is ok. Tv does not have a short inside. We tried connecting a lamp to the source voltage 130 volts the lamp lights up. When we unplug it and plug it back in the lamp does not light up.Power supply does not start. |
| I had a cct190 that smps came up and shuts down. Unpluging the connector to main board smps stayed on. I found ic602 6v reg at 3vdc, replaced to correct. |
| QUESTION NO. P1114-6: I am reparing an RCA F20539DG T.V. but this brand´s diagrams are hard to find in Mexico since the company started its sales activities recently. Is there any site where I can get service manuals for RCA products or a place to buy them? |
| Suggest looking at the Howard Sams Fotofact web site. Search by model and Chassis Numbers,[CTC-XXXX]including the letters following. Either that or a local distribrutor for Sams Fotofacts may be able to order item for ud. RCA in Indianapolis probably would supply the schematic to an authorized servicer. |
| QUESTION NO. P122-5: I have a NEC 25" tv/monitor model ct2501(a) with vertical foldover at the top of the screen, with retrace lines coming down 5 inches from the top of the screen. It is a filter problem but I do not know what area it is coming from. |
| It is probable that one of the filters in the vertical circuit has dried out. It is also possible that the output device could be bad. |
| QUESTION NO. P1124-8: I have an Emerson TV model MS198RA that will only display a green color on the screen (not a green colored picture). When I turn the TV on, maybe 1 out of 10 times the picture will be normal for about 1 minute, then it will change to a bright green with no picture. The audio continues working fine. The other 9 out of 10 times there is never a normal picture, only the green screen. |
| There is probably a short from the heater to the cathode in the CRT. |
| QUESTION NO. P1126-8: I have a Magnavox 27" TV RJ5540 AK01 (chassis 27G1-01) don't have a schematic yet. Relay clicks when power is depressed no pic or sound. R448 glows.I cannot read the value well. It looks like color code is brn-blk-grey-gold (1,000M 5% ?). |
| 1 ohm, 1 watt. This resistor is protection for 130 B+. Better check your flyback and HO Transistor. Sams#2676 |
| QUESTION NO. P1125-5: I have a 27" RCA TV model F27632SE chassis number CTC177BH2 the original problem was the picture drops down about 2 -3 inches, turning the power off and back on would sometimes correct this. After being bumped the volume display does not function properly it stays on the min. setting and cannot be adjusted with the remote or using the front panel (there is no sound). Also pressing the remote TV on a second time produces a black screen with" H3:60 PM FM 88.1 " displayed. Pressing channel + increases the FM stations by.2 until FM 107.9 then NWS A, NWS B and back to FM 88.1. Is this a bad Eprom? |
| Do all the poor solder repairs per RCA specifications. Order a new Eprom, hopefully you have an operational computer and software from RCA to reprogramme the Eprom. If not, enjoy reprogramming it from the service literature. Should repair your problem. |
| QUESTION NO. P1120-4: I have a 27" RCA TV model F27632SE chassis number CTC177BH2 the original problem was the picture drops down about 2 -3 inches, turning the power off and back on would sometimes correct this. After being bumped the volume display does not function properly it stays on the min. setting and cannot be adjusted with the remote or using the front panel (there is no sound). Also pressing the remote TV on a second time produces a black screen with" H3:60 PM FM 88.1 " displayed. Pressing channel + increases the FM stations by.2 until FM 107.9 then NWS A, NWS B and back to FM 88.1. Is this a bad Eprom? |
| First thing to do with a 175, 176, or 177 chassis is resolder the grounds on the shields for the tuner & microprocessor. Be sure to remove the bottom shielding on the tuner to get at the ground connections inside. This should fix picture height problem, possibly audio, snow, and intermittent power as well. As far as the EEPROM see P512-1. Immediately after plug-in the voltages may oscillate (set having problems) for a while on EEPROM. Check when they steady out after 10 secs or so. |
| QUESTION NO. P1114-2: I am looking for a list of valid parameters for the rca ctc 175c, chassis. The ones that I have from a different chassis are not working. |
| From what I've seen, parameters for a 175, 176 and 177 chassis are all about the same. At any rate the 3 security parameters are the same. Try varying the horizontal frequency to get a picture first & verify picture is "good" by going to next parameter (02) then adjust the rest. See http://www.elmswood.guernsey.net/ctc177.html for the details. |
| QUESTION NO. P1117-7: I have Zenith TV Model SLS2555S with Q3431 Blown apart. I am trying to get the schematic but supplier says it is not available. I would like to know if anyone has had this problem. |
| 121-1264-01 is the part number of the transistor that is blown apart. Usually
the regulator transistor str? is sometimes shorted also. This is probably either due to a
power surge or lightning but the most likely cause is the picture tube starts arcing and
blows the power supply. I have seen a lot of tubes do this. |
| I have one in my shop too. These are the parts I replaced in the power suppy: ICJX3431 (STR53041), Resistor (rx3433), Resistor(rx3433), Q3431(NTE123ap). |
| QUESTION NO. P1118-7: Mag. 25d500 chassis, 93 model. has an aft problem similar to problems they have had with the saw filter. Have changed the saw filter, aft coil, and swapped the tuner. Works ok with a tuner snubber. Voltages at tuner seem to be ok. Anybody seen this? |
| The problem was the aft coil and someone had cranked on the rf agc control at another shop. |
| QUESTION NO. P1030-7: I have a Emerson EC133A that has no color the IC voltage and waveforms look great. Sometimes you can see a faint osc of color. I have changed the crystal and checked the capacitors around circuit. |
| I had a similar problem with a sony monitor. The problem was a false contact in the solder. So resolder all pins. |
| QUESTION NO. P1030-9: Sharp TV #25RV69/ Picture shrinks to small white line in the middle of screen. Tap the flyback or Hor. Yoke and picture jumps back for a few seconds. Anyone run into a similar problem or have any recommendations? |
| I have had the same problem and it was an intermittent vertical o/p ic, lightly tapping the heat sink will cause the vertical to collapse and return. |
| You do not specify the model but check if the unit has a sound module made by Sony. You can bypass this module, put (2 channels) a caps 50v10uf (probe to see audio) and check trace to out (it is a SAP decoder, do not need this in certain countries). |
| QUESTION NO. P1013-5: Mitsubishi CS-2701R. After replacing vertical amp la7838 vertical deflection was restored but will not adjust down to fit screen (excessive deflection).B+ voltages appear correct. |
| There is a 1ufd capacitor normally tantalum but in some cases a regular electrolytic beside the o/p that goes leaky. |
| QUESTION NO. P1016-11: I have an RCA CTC166CR which will not power on. The high voltage is OK. All voltages at the low voltage power supply are OK. No derived volts from flyback.When power switch is pushed indicator light comes on, flashes 3xs then goes out. H.O.T. ok. Could the problem be in start-up? Xtal is ok micro has power, reset ok. I have two of these tv's with same condition. |
| Ground pin 18 of u3101 see if hv comes up if not cr4103 is breaking down check on pulse at pin 18 of u3101 check colector voltage of q4161 if low (19v) replace c4605 measure r4163 should be 1.2k. |
| QUESTION NO. P1016-8: I have an RCA CTC177 that had the ususal bad ground under the tuner however this set also has narrow horiz width and picture is fine for a few minutes then pulsates goed to vert line the all snow as if the cable was unhooked (can't turn off when this occurs. Once I heard a arching noise just before turn on ofter plugged in. |
| Check r4517, r2709 off pin 4 of ihvt also cr4402,q4851 and pin 2 of l4853. |
| QUESTION NO. P1026-4: Working on RCA CTC 131-A. This set has the chopper power supply. Originally, set came in with shorted chopper. Replaced and set worked fine for about one week. (Also soldered base and emitter) Set returned with blown main fuse, and blown chopper. Replaced chopper. Set continues to blow fuse. Chopper is O.K. now. Replaced chopper cutoff (Q100). Still blowing fuse. (Checked C105, O.K.) |
| Ground tp 408 while ac is applied and see if set will come on. Also check CR301 for short I have also had R103 open intermittently. |
| QUESTION NO. P1021-3: I am working on a Mitsubishi (Electrohome in Canada Model 66CG01 which has no colour. Video is good, everything is good except for colour either on the main screen or PIP. |
| You have a problem on the pip board, may have a bad trimmer cap for 3.58 crystal on bottom left side looking from back or a bad feed through on the double sided cct board. |
| QUESTION NO. P1024-2: I am working on 27" RCA TV CTC140AJ that has an intermittant power problem, the set would for awhile and turn itself off but would come back on immediately, other times it would go into on & off mode constantly. I have checked to sheilds and resolder most connections also, checked for cracks on PCB. |
| Remove the sub-power board that houses the rectifier diodes. Resolder every connection and then reinstall the sub-power board. |
| iThe pwr on/off,volume, and other functions pass through the tuner module. Take the cover off the tuner and resolder all cracked or burned connections. |
| QUESTION NO. P925-1: I am working on a 10 year-old Mitsu 2654R set that has no vertical deflection, only a horizontal line, although the problem is intermittant (more often than not). When the problem does not manifest itself, the picture is "wavy" until the set warms up. I have cleaned the boards, but the problem still exists. |
| When not working check for vcc on vertical to see if vcc has dropped off or just dropped enough to cause this problem. Take the vertical trans. # & cross to ecg, find diagram of part, look for vcc on 2 places on chip or should be if it is a 12 to 14 pin vertical. |
| QUESTION NO. P929-3: I have a mitsubishi cs1942r with int. audio and video flickering. The tuning voltage drops out, but I cannot isolate trouble. |
| Check for brown glue on the main board & assoc. boards. This is a common problem. Remove all of the glue you can find. |
| QUESTION NO. P1010-9: I have an Emerson 25" TV model TS2581RD with a supply limiting 3W resistor, R251, burned up. What value is this resistor, the ink evaporated when it blew. |
| There doesn't seem to be a R251on that chassis. There is a R521,however, that fits your discription. It is 4.7 5% 3W and goes to pin 3 of IC501. |
| QUESTION NO. P1010-7: I am working on a Zenith SLS2553S 25" television. I seem to only have green and red. For about a day, the picture would eradically switch between all blue and a "normal" picture. Then it stopped turning blue and I was left with a very green looking picture. Any clues? |
| ANSWER 1: Check for ring cracks at the video output transistors on the video output pcb. Common problem. |
| ANSWER 2: Check for bad connections of the crt, but I think you'll find that the picture tube is bad, they've had alot of trouble with the tubes in those. Sometimes they will exchange even if barely out of warranty. |
| QUESTION NO. P106-13: I am working on a 1987 Sears color TV, on the inside it looks like a Toshiba. The problem is the tint control does not hold and when adjusting the tint it shifts about randomly. I've located the tint section on the board and was wondering if this inability to lock the tint might be caused by a leaky capacitor. I cannot get the schematic for this set (model no. 562.40320700) so if anyone has an idea what I should look for I would appreciate the help. |
| If ANY controls have not been rotated in a while they will exhibit these symptoms. Spray out w/cleaner/lubricant Chemtronics tun-o-power or the like to solve problem. |
| QUESTION NO. P930-3: I have a RCA PTV CTC 169BT retrace in all tubes can turn out with bias but then picture washed out pulses. flyback rings good ok no screen adj on flyback. |
| I sugggest checking G2 source, diodes, capacitors and connections to IVHT. The G2 being non-existant or to low may be your problem. |
| QUESTION NO. P930-5: I have a GE 27GT613 with the CTC177BE chassis that has had
the usual grounds resoldered. All VHF channels (2-13) do not tune. Snow only. All UHF and cable channels normal. The failure occured suddenly while Vhf was in operation. |
| It sounds as if the E-Prom may have given up. I suggest replacement and re-programing data into it. Also check answer for #P-723-1 for link to very good information RE:RCA/GE CTC-177 chassis & it's problems. |
| QUESTION NO P922-5: Sylvania TV RPF702AK01 Looking for value of R400 on main chassis board. |
| According to my schematic, R400 is a thermister Connected betwen the junction of D401,D402 &T402-4, rated at 16.1 cold. PN 483511637005 |
| QUESTION NO. P926-5: Working on a Magnavox Tv chassis # 25N1-01. It had a bad flyback and HOT which I replaced. Now after a few days the Horiz out transistor blows. I put an STK brand in it . Do you need exact replacement transistor for this set? I am unable to locate the reason for the short. |
| Check horizontal driver transformer for poor solder connection. I have had no problem with ECG, NTE or SK HOT subs. |
| QUESTION NO. P912-6: I am servicing a GE TV model 13GP203 chassis TX81E and I changed all the damaged parts except one, which is a resistor, RP41, because it is burned and I can't see the value. |
| I believe the set in question is almost if not identical to RCA TX81F. If this is true, RP41 is 2.2K & connected to the emitter of TP10, the HOT & DX101 cathode. |
| QUESTION NO. P926-7: I have 3 different model Mitsubishi TV's in the shop with the same symtom....int video or no video..sound is ok....models include :CS-27MX1,CS-2656R & CS-2725R. Has anyone had similiar problems with any of these units? |
| ANSWER 1: Inspect the chassis. Is there an upright pcb containing many surface mounted components? This is the pip module, C7001 leaks electrolyte and eats away the fine traces on the face of theboard. Replace the capacitor and repair the defective foil. This should cure your symptom. |
| ANSWER 2: I have seen a CS-2656R with the same problem after being hit 3 times by lightning via co-ax cable, I believe. I did the repair the last 2 times, and both times it was IC202 ( a 12 pin SIP dual video/audio electronic switch ). Scope pins 11 & 12 ( video in/out ) for complete TV signal, or alternately, jump them. If you get video then IC202 is bad. Crosses to ECG7066. Caution customer to disconnect co-ax when not in use! I also remember Mitsubishi tech assistance telling me to check an 8.5V? ZD, but can't remember which one. |
| QUESTION NO. P915-2: I am working on an Emerson model #TC2555D television that when you turn it on, you hear a click and then nothing happens. If you keep trying, eventually it will come on but only stay on for a few seconds. Each time you turn it on, it will stay on longer, until finally, it stays on. But when you turn it off, and let it sit, the process starts all over again. Also, when it does first come on, there is a green tint to the picture, any suggestions? I have replaced the horizontal output, just in case, but no help. |
| check electro. caps. in & around the power supply |
| QUESTION NO. P97-1: I am stumped! I am having a "vertical overlap" problem with a Toshiba CX28409 TV and have traced the problem down to the vertical output IC (AN5521). I have tried replacing this chip but when I do, the fusible resistor connected to the VCC blows and the chip becomes shorted out. I have tried several chips as well as the EXACT replacement from Toshiba but I get the same results. I put the original chip back into the circuit and I have my original overlap problem back. There seems to be a compatibility problem with the replacement chips but I can't for the life of me figure out what it is. One other note: these IC's have a large heat-sink attached which is mechanically (i.e. soldered) to ground.....could this somehow be the source of my problem? |
| Leaky cap, an electrolytic right next to the vert chip. |
| QUESTION NO. P910-9: Toshiba cf2667 has a black band at top of screen. When it is cold it is okay but after on a few minutes the bar comes on. It does not make picture smaller just has black at top 4 inches |
| Use cold spray to find the leaky cap probably electrolytic cap in vert circuit. |
| QUESTION NO. P912-1: Toshiba model CF2768 TV: After approx. 5 min. warmup, motorboating the in audio and dark bars flashing in the video at the same time; however, the raster seems to be okay. The distortion appears to come from the MTS module. Coolant spray has no effect. |
| Probable hair line cracks around the ground connections of the Tuner and MTS assemblies. May attempt repairs with very small iron. Otherwise replace. Both are common failures in Toshiba sets. |
| QUESTION NO. P98-1: Sony KV-2647R television is basically working after replacing a number of components i.e. H.O.T, Flyback, Caps etc., there is too much contrast in fact the whites are very white to washed out or out of focus. to correct the problem the picture control has to be adjusted to minimum with the sub contrast controll also at minimum. It seems that the dynamic picture IC cannot respond to scene changes. The 15.75 volt, 12.66v and 196v sources derived from the Flyback are low. 13.8 vs 15.75, 12.1 vs 12.66 191 vs 196 etc. I have no explanation for this, but I beleive this may have something to do with the dynamic white problem. The transistor, zener and resistors in the 15.75 regulator circuit are OK. Is it possible to have a Flyback Transformer which is not matched properly? |
| It is very possible that you have a crt with low emission. The washed out whites may be blooming. Check the crt before investing much more money or time. 26 " seemed to have a shorter crt life than the 19's and 27's. |
| QUESTION NO. P94-2: I am working on RCA Model F27100AK that has an intermittant power problem. When the set is turned on either by using the remote or pad the set turns itself on and off constantly. The power does not stay on long enough to see anything on the screen. I can hear a clicking sound as it turns itself on and off. |
| The clicking sound your heard was the degaussing relay, it opens to turn off the degaussing coil about 5 seconds after the unit is turn on. Listen for the HV cracking noise when the set is turn on to see if H. output is working. Also check those intermittent shield and EEPROM problems from FAQ. |
QUESTION No. P87-2: Magnavox n25 tic tic. I found d445 but still bad. Any help out there? |
| First solution:I would try removing the vertical output IC,IC550. If this gets the set to power up,I recommend disabling the 27VDC scan derived circuit and use a regulated DC powersupply,preferably one with a current meter,to drive the vertical IC. This will save you time and money if there is another problem causing it to burn out the IC. I would also check the 121VDC regulated powersupply.If it is not being filtered like it should it could cause a spike voltage on the secondary windings of the flyback and will cause D445 to fail. If C411(100MFD 250VDC)changes value just the right amount it will not show up in the picture or raster like a regulator problem but it will show up if you scope pin 7 on the flyback. Second solution:If I remember right the set will tic if the Hor. Output Transistor is shorted. |
QUESTION No. P821-8: I have a Sony KV-27EXR10 that came in dead replaced strs6031 now the set comes on but the B+ is only 100V all other voltages on the G board are also low ie the -22v is -15v and the 15v is 10v the B+ is supposed to be 135v. The ic does not appear to be running hot and cold checks on the components on the G board seem to be fine. |
| Check for defective 135v reference regulator IC SE-135N (TO220) optocoupler, 2SA1175 OVP-1 transistor and related circuits. |
| QUESTION NO. P826-8: Symphonic Mod#TVCR13D1TV has a luminance problem. The brightness is at high but picture is dark and flickering. |
| Check G2 voltage, if not stable, screen / focus divider on flyback is bad replace FBT, also check resistor in ABL circuit. |
| QUESTION NO. P828-11: I am working on an RCA TV CTC167C chassis. The problem is that there is no video, the display works but looks as though it is shrunk a little on top. Everything else works fine. Anyone had a problem like this before? |
| Problem caused by a shorted boost-trap capacitor in vertical output circuit. That is an electrolytic capacitor between cathode of pumpup diode and vertical B+). This would cause DC level to shift on vertical blanking signal and kill the video signal. |
| QUESTION NO. P828-3: I am working on a TH-33VS10 Panasonic T.V. (possibly the Japanese name). The picture is great except for a complete lack of red. |
| Check red cathode pin with an oscilloscope for proper signal average DC voltage on any CRT cathode should be about 150v if singal is present and voltage is correct, CRT is defective. Best still is to check with a CRT tester. |
| Have you ever tried switching drive signals at the point of entry into the CRT board? This will tell you a lot especially if you do not have a CRT restorer. |
| QUESTION NO. P93-4: Magnavox 31U1 with 1" triangle spot in center of screen at turn off. Spot remains for 15 minutes or until anode voltage of 25 to 30 kv is drained using hi-volt probe. The original problem was a defective tuner. I did not notice the spot before and thought I had created the problem. Checked possible bleed path of R539, R572, R573 off DAG line and C511. Also ground from chassis to CRT board. |
| The symptom you are describing is known as "AfterGlow" and is caused by the persistance of the rare earth phosphers. RCA has had this symptom for many years and assure technicians and customers this is visable evidence the crt is good quality. RCA would comment that the longer the afterglow persisted the better quality vacuum, tube quality and probable life expectancy. I have seen this symptom numerous times and have seen no determental effects from it other than kids circling it with crayons. |
| QUESTION NO. P828-1: I am going to pick up an Hitachi television model # CT4532 The television has a transformer problem (perhaps flyback) and I am trying to determine how much work I have ahead of me. |
| Unless you receive this set as a gift don't get too excited. Some of the components may not be available any longer from MFGR. Horiz drive and Flyback have been a source of service problems. Also regulator and convergence related failures. Over-all these sets were quite reliable however, as they age, as with all things, other things do and will happen. If you enjoy a challenge go ahead. |
QUESTION No. P811-3: I have a Zenith model SS1937S9 television that has a problem with a picture that slowly fades to blue after it has been on for a while. It will gradually return to normal after a while, but some times it will stay blue until the set is turned off then back on again. |
| The problem is that you have a short in your blue gun inside your picture tube. It is a common problem with Zenith's. |
| QUESTION NO. P824-4: I have a SEARS LXI TV. Its about 7 years old. One of my kids hit some combination of keys on the remote and now a message scrolls continually thru the picture. This happened a couple of years ago and a repair person was able to give me the combination to turn the message off. I lost the combination. Can anyone out there help? |
| Try pushing the volume up and down buttons at once. |
QUESTION No. P812-2: I have an RCA TV that has no color; chassis ctc157. I have replaced the ic1001 chip, xtal, resisters and caps in the circuit and still no color. When I inject 3.58, I have got color. Voltages all check good. Need some help on this one. |
| Replace C2812. Fairly common problem. |
QUESTION No. P821-2: Toshiba Model CX2778 when plugged in the power relay clicks very fast. Jumpering contacts on relay for troubleshooting resulted in clicking, stopping after about twenty seconds and set runs fine once warm. I suspect negative voltage regulator STRD 1005. Has anyone come across this? I should also note it is not necessary to push the power button for relay clicking to start. |
| Toshiba CX2778 no power due to open cap 840 (330uF16V105 deg.). Also change C841, C822. Check for bad resistors, diodes, etches due to overheating. |
QUESTION No. P89-3: I am currently working on a Zenith Sentry 3 Model H2013Y7 that powers up as soon as it is plugged in. I replaced IC 6000 but to no avail. I compared it to a working set of the same model and the only difference I noticed was a constant 5v on the input to the switching transistor for the power supply. When power is on the screen gets a raster that is green snow and cannot change channels. |
| I believe your set is in hotel mode. Get into the service Menu by continously pushing the menu button on the remote untill the menu goes away them push 9,8,7,6 enter. you will find a listing for hotel mode turn it off. |
| Once the service menu is activated by the menu, 9876 routine you should see a selection to set the auto power on. Many of these are plugged into the cable boxes and customers seem to prefer them to have the tvs come on when the cable box is turned on rather than using two power commands. Simply turn the auto power function off in the service menu.Being in the Hotel or private label mode seems to have no effect. |
QUESTION No. P87-3: I have a Mitsubishi 27" late model with low volume from audio output on - via RCA jack - on back of unit. Need suggestions on how to adjust. |
Most Mitsubishi TV's audio output RCA jacks are variable level controled by TV volume control, volume has to be turned pass midrange to have decent RCA output level but you can always turn off the speaker with speaker switch or speaker control on menu. |
QUESTION No. P87-11: I have a TV GE model 27GT618 with chassis ctc187BD2 which has no pic or audio. I have all of the non flyback power supplies working, but the flyback derived supplies are dead. There is no drive to the hor out transistor. The drive should come from the t chip, but there is none. The EEPROM has a running clock/data, although I do not know if it is correct. At least it is not dead. Is there an easy way to isolate the problem? Can I somehow "jump start" the horizontal to bring up the other supplies? |
You maybe able to jump start the tv by doubling the safety cap. |
QUESTION No. P730-7: I am fixing a 27" Sony Trinitron with digital tuning (Model No. KV-2780R) which when the set is initially turned on, it seems as though the station is not tuned in properly. You see the tuned station, but with a bit of snow, and the sound is somewhat distorted. |
I usually replace the tuner assembly rather than attempting repairs. Also the if/mts assembly may also have intermittant connections which can exhibit symptoms such as bad audio, snowy pix, intermittant breakup of pix, poor sync, etc. I have done quite a few of these and just order and replace the complete units. |
QUESTION No. P726-2: I have an RCA CTC130 and color does not come in on ch 3 and 5. Any thoughts? |
You did not state if you are using direct broadcast or cable hookup. First thing I would check is to substitute the tuner if available. Supply NTSC standard signals to the RF input and see if colour is present. If so suspect shifted frequency signals from CATV source. AFT circuit may be to tight to lock onto centre of channel allowing proper reception. Also, read section 12.1 of Sam Goldwasser's TV Repair FAQ at http://www.anatekcorp.com/articles.htm. |
QUESTION No. P725-5: This is a Zenith set came in without a mod.# (Label had been peeled off). It seems to be about 4-5 years old. At first no video with an on screen prompt that said "AC Line is failing" and then dead set. |
Zenith TVs have part numbers for the modules affixed to the modules. There is a small white tag showing the part number. It will start with 9-XXXX-XX. Having that information will allow one to order replacement modules. Sounds as if the standby power supply and mpu may have sustained damage. |
QUESTION No. P722-1: I am working on a RCA Model F20251WN with a CTC176F2 chassis. The unit does not power up when the power button is pushed. No power relay click but I read 130 volts near the switch mode regulator STK730-010 and 148 volts at the horizontal output transistor. I read voltages on it and 3 pins read 4.* volts. |
Some time these set get off frequency so this works some times. Take the safe cap put another on top, this will let the thing power up. You will not hear the relay. Then turn power on and hold. Now push menu and push power on two or three time then push volume up. That should get you there. On most ctc chassis you have to resolder the the tuner grounds. This is the first thing to do. There is a code to get in to the memory of these sets. |
QUESTION No. P723-1: I need to know the sequence of programming for the memory in a General Electric, model 27GT613 TV. |
Refer to the article at http://www.elmswood.guernsey.net/ look under TV and RCA/GE refer to the excellent description about the CTC177 and it's faults. Included is a guide to programming the E-Prom. |
QUESTION No. P718-4: RCACTC177AF2/3 original problem was a grainy picture. I checked out the tuner and it had the cracks as usual. I resoldered the tuner, and micro shield, now I have no power. I replaced the eeprom with no luck using rca part# 218399. I have 165 coming off power supply. I have 149 volts at horizontal output transistor. I have checked the power switch and it is good. I have also replaced cap c7v a 200 volt 680uf that was reading 62 volts to ground. After replacing read 0 volts to ground. Same problem, no power up. |
CTC-177 Check http://elmswood.gurnsey.net/ for a good tech writeup on this chassis and hints on many repairs. Also EST Mag July 97 issue has a very good article. |
QUESTION No. P77-2: I have a JVC 27" color TV model AV-2751S. The verticle sweep quit. White horizontal line across the middle of the screen. What is the most likely cause? |
Resolder cold solder joints on the vertical output ic. |
QUESTION No. P77-11: RCA F27195CP Chassis CTC140 will not power up. The front panel or remote power switch causes high-pitched sound, then set turns off. Before, set would sometimes power off, but would come back on by itself, or after a while the power switch would turn it on. |
Remove sub power board that contains the power supply diodes. Clean off old solder and resolder each diode and connecting pin. Reinstall sub power board. Also check for ring cracks arround IVHT and in area of IF SAW filter. Numerous intermittant power problems have been due to bad solder joints on the sub power pcb and cracks near the flyback. |
QUESTION NO. P616-3: Toshiba TV model# CX2978C works fine when video is connected to the RCA inputs using a VCR to change channels. When connected to RF1 or RF2, no video, just snow with hiss for sound. Replaced tuner same problem. |
These Voltages are close as to what I remember: AGC around 2.5V, BM 11.9 to 12.1V, IF 1.5 to 1.9V, CLOCK/DATA/ENABLE 0 to .1V P to P. There should be 30V and 5V if any voltages are low or missing desolder the tuner from the unit and trace voltages back. |
QUESTION NO. P610-4: EMERSON TC1365B seems dead. Pressing power button causes relay to click. No H.V. H.O.T. checks good. I have replaced IC501 voltage regulator with no change. |
Is there 165V on Hout Emitter? If not, trace from Hout back thru till you find Resistors,ect..(of course be using a variac). If there was 165V on Hout there are two possibilities: either No HDrive or VOut is shorted or no VOut Pulse. |
QUESTION NO. P613-1: I have a GE Color TV (AB/AC Chassis) that has a perfect Black and White picture but NO color. So far I replaced the IC300 Color IC and that did not help. I did that because I saw no color signals at the 3 output pins of IC300. I hooked up a color bar generator for test purposes and see there is color signal getting to the input pin of IC300. I resoldered many griplets and that did not help either. Anyone have any further clues as what to look for? I suspect that the problem is somewhere near IC300. |
Check r326, r322 and c328. Also instead of just soldering the griplets you may need to wire around them on the bottom side of the board. |
QUESTION NO. P67-1: Samsung mod#TC2540S sometimes comes on with only about 4in. of height in the center of the screen. |
I have found many problems with vertical compression or foldover to be due to bad higher voltage electrolytic caps (100v and up), typically 2.2uf to 10uf in the vertical output/drive circuit. They are often discoloured making them easy to spot. Also check for the usual, cold solder, power supply voltage to vertical stages. Yokes are rarely bad. |
QUESTION No. P63-2: I have an rca chassis ctc130 it will be on for a few seconds and the picture shrinks up on one side and takes out the HOT. Flyback is Ok and so is Hoz. Yoke. |
Replace hot emitter resistor with the exact value. All the HOT current passes thru this resistor |
QUESTION NO. P67-6: I just fixed the power problem on an RCA console TV (model # GU795H) but now when I change channels it loses the vertical sync. If I adjust the vertical size down, the scrolling stops and I can change channels all day and everything is fine except now I have a shadowbox TV instead of a full screen TV. I can adjust the vertical size back to normal and everything is just fine again until I change the channel and then the process starts all over again. |
Read section 9.5 of Sam Goldwasser's TV repair document, downloadable from this site. |
QUESTION No. P520-1: Is anyone familiar with an RCA CTC 175 chassis that exhibits low audio output, even at maximum volume? |
ANSWER 1: Perdon por no escribirte en tu idioma pero existen 2 soluciones pero el problema es causado por la EEPROM. 1a.- Solucion economica; Desconectar Colector de Q1903 (audio mute Transistor) no es lo correcto pero soluciona el bajo volumen y ademas trabaja el mute. 2a.- Reemplazar EEPROM; pero antes verifica la configuración que guarda, para que la vuelvas a grabarla, (solución Correcta). |
ANSWER 2: Replace eeprom. Go into service mode and copy all the values first. Then install new eeprom. After starting set install your copied values into new eeprom. Do not remove anything from chassis and while you are at it resolder all the ground connections around micro sheild and under tuner shield. |
QUESTION No. P512-1: I have an RCA CTC177 chassis. Power does not turn on. Pin #5 on U3101 should have 0V but it is 5V. Is this a bad U3101? |
First check voltages on U3201 (EEPROM) pins 1,2,3,4,7, are ground, pins 5,6,8 should be about 4.8v, if not replace U3201. When replacing the EEPROM you will probably need to program it or else be sure to purchase one preprogrammed. If you need the parameters to program in look on a Sam's set 3221 or post a question here. RCA/GE Colour TV Chassis. From CTC-169 and above. Severe pincushion distortion or dead chassis. Stand by supplies may or may not be functional. Check horiz. output for short in dead chassis. Replace pincushion damper diode and associated capacitor. Usually a .056 or close in value. Also HOT if shorted. Symptom found in direct and rear projection chassis. Confirm desinated value of pincushion capacitor for proper value. Varies from chassis to chassis. Bad cap may appear swelled. |
QUESTION No. P58-1: JVC AV2590 with vertical collapse. Replacement of C420 restored the full screen but I now have vertical rollover 3" at the top. I have checked and/or replaced caps in line to yoke with no results. Voltages appear normal. I can adjust screen on the flyback and set will nearly collapse. |
Make sure you replace C420 with exact same value, also bridge caps. in vert. with same value, this is critical. Also check for and remove any glue that is used to hold components on copper side of pc board as this sometimes causes leakage between traces. |
QUESTION No. P51-5: TV/VCR COMBO brand=MEMOREX model= 16-410 not turning on. The Low Voltage PS is not on. If the 5V load is disconnected, the LV PS comes up, but set cannot be turn on. 5V regulator and several caps had been replaced. |
C1026 470uf 16 volt. |