PRO2004.3

From: rayssd!raybed2!ewb@g.ms.uky.edu  (EUGENE BALINSKI)
Subject: PRO-2004 MODS

    In response to numerous inquiries I am posting a short overview of the 
mods to the Radio Shack PRO-2004 scanner. First, all mods are done at
your own risk. I assume no responsibility. I do not know what effect they
(the mods) will have on any warranty, however I would think they would
probably void it. Also, one of the mods restores coverage of the cellular
phone frequencies. 

These mods are detailed in the following articles:
a) POPULAR COMMUNICATIONS AUG 87, PP 18-20
b) MONITORING TIMES OCT 87, P 53
c) MONITORING TIMES DEC 87,P 60

I suggest strongly that you obtain the back issues and read through the letters
or articles. I also suggest you subscribe to the mags. They supply a lot of    
great info and freq lists. Now the mods.
 
1) Restoring 870 MHz coverage.
First treat the radio as if it were CMOS, that is make sure you and it have no
built up static charges. UNPLUG THE RADIO FROM THE AC OR DC POWER SOURCE AND
ANTENNA !!!!!!!! Take the radio out of the case by removing the 4 screws on 
the back. Carefully invert the radio. Locate a box-like sub-circuit. It's 
near the switch marked "restart". The sub-circuit should be marked PC-3.
Carefully pry off the cover of the metal box. Inside there will be a 64 pin dip
IC. This is the radio CPU. Be careful not to touch or short out any leads on
the chip. Near the chip there will be a row of diodes marked D-502 to D-515.
If D-513 is present, cut one lead, separate it so they will not touch, and 
magic, 870 Mhz is restored. If D-513 is not there and you still do not have
870 coverage, then a little more work is in order. Locate the 9 pin connector
"CN-501". Carefully remove it from the sub-circuit. Unscrew the screws holding
PC-3 to the main chassis. Carefully invert the sub-circuit board (PC-3).
Locate the one lone component on that side of the board. If it is a diode,
as it should be, then cut one lead and separate them as above. Re-install the
sub-circuit with the screws on to the main chassis. Reconnect the 9 pin 
connector. Do NOT put the cover back on just yet ?!  
CONTINUED IN PRO2004.9