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Most of the models discussed in this article are base/mobile units made by Electra during the 1970s and 1980s although some of the capacitor failures occur in the Uniden BC800XLT, too.
Electra stamped all of its scanners with a manufacturing date code on the rear of the cabinet. The code is comprised of a single character (C = Cumberland, Indiana, P = Puerto Rico), followed by four digits denoting year and week the radio was built. For example, "P8422" denotes the radio was made in the Puerto Rico factory during the 22nd week of 1984.
If Uniden doesn't have a schematic, try obtaining a Photophacts from Howard Sams Publishing division of Prentice-Hall at (800)428-7267.
G & G Communications (telephone (716)768-8151) is a family owned company which repairs scanners and stocks parts for several older models, especially Electra/Bearcat and Regency brands, but they don't sell manuals or schematics. They are located at 9247 Glenwood Drive, LeRoy, NY 14482.
Electronic Repair Centers in Franklin Park, Illinois (telephone 708-455-5105) has been repairing Bearcat scanners for several years. They charge a flat $45 repair rate for programmable and $30 for crystal scanners, and shipping is extra. Electronic Repair Centers will fix Regency scanners if they can obtain the parts.
The Electra/Bearcat BC350, BC300, BC250, BC220, BC20/20, BC211, BC210, and BC210XL models were hand assembled, and every one I've serviced had several connections that were either soldered poorly, or not soldered at all.
Resoldering joints on the ribbon cable connecting the RF and keyboard logic circuit boards in a BC250 attenuated the microprocessor/synthesizer hash noise noticeably.
A Bearcat 20/20 was experiencing periodic loss of memory on some, but not all channels. When the problem occurred, the frequencies on some channels would be completely changed. On other channels, the frequency would still be intact, but the channel would be locked out, and the delay toggled from "on" to "off". Some channels were not affected.
The 2 "AA" memory backup batteries, and their holder, tested good. Much time was spent tracing logic, heating and cooling components, and making voltage measurements.
One of the secondary leads from the power transformer was connected to the main circuit board through a hole drilled through foil traces on both the top and bottom sides of the board. A close examination revealed that this lead had been soldered only on the top of the board - the bottom side had never been soldered.
Soldering the lead on both sides of the board solved the memory loss problem.
In almost a dozen of the BC300 and BC800XLT scanners I've fixed, C98, a capacitor in series with the primary of the switching transformer failed, causing the output of the supply to drop below the level needed to power the display. The switching transformer is mounted on the RF circuit board, and is much, much smaller than the main power transformer, which is usually fastened to the metal chassis. The 22uF/16V capacitor used for C98 in early BC300s was marginal, and was replaced with a 47uF/25V capacitor in later units.
I replaced the 22 uF capacitor in the switching power supply stage of a BC210XL which caused the same symptom. Other capacitors in the switcher stage have failed. C114, a 4.7 uF/35V tantalum capacitor failed in at least one BC250, causing the display to blank.
A more sinister problem affects the switcher in earlier models. The switching supply stage in the BC250 and original BC210 is driven by a clock signal derived from a custom Exar NC57902 divider integrated circuit (designated IC6 in the BC250 scanner). I've seen this divider IC fail in several BC250s, causing a blank display (except for a decimal point in the BC250's rightmost digit). This custom IC is no longer available from Uniden.
A Philips ECG291 will work as a substitute for the TIP-29. Don't try a Radio Shack substitute, it hasn't worked. See Martin Toomajian's article, "Bearcat 250 Erratic Display Cure", in January 1987 Monitoring Times.
A similar problem in the Bearcat 20/20 was discussed previously in the section on bad solder joints.
Although the potentiometer is adjusted at the factory, changes in component values due to aging often necessitate readjustment of this internal pot. Misadjustment of this pot has been the cause of "no squelch" complaints in two BC300s and a BC250 I fixed.
Another squelch failure is due to a blown transistor that acts as the electronic switch in the squelch circuit. I replaced this transistor in only one BC300, so I don't know if this is a common problem.
If your scanner is completely dead, check the primary of this transformer for an open circuit condition.
Andy Domonkos reports he often uses a tape recorder connected to a Uniden/Bearcat BC890XLT. RL-1, the carrier activated relay inside the BC890XLT wore out. Andy found the identical relay sold at Radio Shack (part #275-232) and says the BC9000XLT uses the same relay, too.