Repair Tips for Radio Shack Scanner Radios

September 27, 1998.

Copyright (C) 1997,1998
Bob Parnass, AJ9S (parnass@bell-labs.com)
--- All Rights Reserved ---

NOTICE: This article may not be reproduced in whole or in part on CDROMS, in bulletin boards, networks, or publications which charge for service without permission of the author. It is posted twice monthly on the USENET groups rec.radio.scanner, alt.radio.scanner, sci.electronics.repair, and rec.radio.info. It is also available electronically from the rec.radio.scanner ftp archive on the official USENET FAQ library ftp://rtfm.mit.edu/pub/usenet-by-group/rec.radio.scanner. The author writes a monthly "Scanner Equipment" column for Monitoring Times magazine, published by Grove Enterprises, but views expressed in this article are his own.

Introduction

Radio Shack has been selling scanners and monitor receivers under the Realistic and Radio Shack labels for over 30 years. Most of them were manufactured by General Research Electronics of Tokyo, though many newer models are manufactured by Uniden.

The date of manufacture is usually printed on a gummed label on the scanner as well as the cardboard box. A code of 12A5, means the scanner was made in the 12th month of 1975, 1985, or 1995, for example.

There's another way to date Radio Shack scanners manufactured by Uniden. The first digit of the long serial number is usually the last digit of the year of manufacture.

Another way to roughly estimate a radio's age is to examine the 4 digit date codes often stamped on the integrated circuits. The radio must have been made after the most recent date stamp.

Schematics, Owner's Manuals, and Parts Available

I cannot furnish schematics, manuals or parts. Service manuals for most Radio Shack scanners sold through mid-1997 may be ordered through your local Radio Shack store.

If Radio Shack doesn't have a schematic, try obtaining a Photophacts from Howard Sams Publishing division of Prentice-Hall at (800)428-7267, http://www.hwsams.com/sams_model_new.html

Parts lists for recent and many older models are available on line at: http://www.radioshack.com/ProductSupport/Frames/. Parts may be ordered through Tandy National Parts, telephone (800)442-2425 or (817)870-5600, or through your local Radio Shack store

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. (http://www.iinc.com/ggcomm/ or email ggcomm@iinc.com or ggcomm@aol.com)

GRE-Built Base Models: Dim Backlight

The backlight in many base models, including the PRO-2022, PRO-2004, and PRO-2005/6 is implemented by an electroluminescent panel, which grows dim with use.

The EL panel used in the PRO-2005 and PRO-2006 is designated EL-501, and is identified by Radio Shack part #10800050. A new EL panel can be ordered through your Tandy National parts (see above) or local Radio Shack store and sent to your home. Radio Shack no longer sells replacement EL panels for the PRO-2004.

Replacing the backlight is an operation which requires care and patience. Purchase a service manual, and study the exploded parts diagrams as you read the following steps.

Top and bottom cabinet pieces must be removed, then the speaker unplugged from the main board. The front panel assembly must be removed from the chassis by removing 4 flat head screws, 2 on each side. You need not disconnect all the wiring harnesses, though you might have to unplug one so it won't get in the way of a hot soldering iron.

Unsolder the bare ground wire soldered to a large shield on the back of the front panel, located near the back of the squelch control. Two ground braids must be temporarily disconnected by removing the screws which fasten them to the chassis. After removing the volume and squelch knobs, you must remove 8 small screws which fasten the plastic front panel to the diplay board.

The old EL panel is fastened by a bead of glue and two foil type leads soldered to the display board. It's easier to cut the two leads from the old EL panel before unsoldering. A sharp knife should be used cut away the glue. The old EL panel can then be slid gently out from behind the LCD display.

The new EL panel can be installed by reversing the process, though I found that it is not necessary to glue the new panel. The two foil leads must be soldered using a minimum of heat. Reassemble the pieces in reverse order of disassembly.

GRE-Built Portables: Worn Out Keypads

The keypad on late model GRE-made Radio Shack portables, e.g., PRO-39 and PRO-43, can become unreliable after prolonged use. The best repair is to replace the rubber keypad instead of trying to restore contacts using chemicals. A replacement rubber keypad may be ordered inexpensively through Tandy National Parts or your local Radio Shack Store.

PRO-43: Loss of Audio

Early PRO-43s were built with a 200 mW speaker (mfr's part #EAS-3P123A). The voice coils in some of these speakers have opened, resulting in lack of audio output, though audio is still available from the earphone jack. A more capable 500 mW speaker is available through Tandy as replacement (EAS-3P127).

PRO-43: Freezup

If you attempt to lock out all 20 channels in a memory bank, then scan only that bank, your PRO-43 will freeze up and be placed into a catatonic state. Use the procedure documented in the PRO-43 user manual to fully reset the scanner. This will "break the trance," but all the memory channels will be cleared.

PRO-2004: Dead

If your PRO-2004 is completely dead, check R235, a 1 ohm, 1 watt resistor mounted vertically on the main board.

PRO-7A: Channels 1 - 4 or 5 - 8 Dead

If the first or last 4 channels in your 8 channel PRO-7A crystal scanner are not working and the lamps for those channels won't light, replace IC4 or IC5 (type 7400A).