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REPAIR TIPS: RADIO SHACK SCANNER RADIOS
Copyright 1997 - 2001 by Bob Parnass, AJ9S
[NOTE: 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/.
The author writes a monthly "Scanner Equipment" column for
Monitoring Times magazine, published by Grove Enterprises,
http://www.grove-ent.com 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.samswebsite.com
Parts lists for recent and many older models are available
on line at: http://support.tandy.com. Parts may be ordered
through Tandy National Parts, telephone (800)241-8742, or
through your local Radio Shack store. You may be able to
obtain some technical assistance from Tandy by calling
(800)843-7422, option 2. The RSU (Radio Shack Unlimited)
phone number is (800)-433-2024. Grove Enterprises
http://www.grove-ent.com occasionally sells manuals, too.
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 7825 Black Street Rd., 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, but Robert Cummings
has modified an LCD from a Miller Engineering
(http://www.microstru.com) experimenter's kit and fitted it
to his PRO-2004. See
http://home.cfl.rr.com/scan/Backlight.html for details.
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 (PRO-43 keypad is
RSU#10789808) 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).
--
==============================================================================
Bob Parnass, AJ9S parnass@bell-labs.com
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