-*>You mentioned that your friends pro-43 was modified. This isn't
-*>quite relevant, but would you happen to know how to modify a
-*>pro-37? I have tried to use pro-38 modification instructions
-*>(on the off chance that they might work) but obviously they don't.
Here you go. These are the ones I used on mine.
Subject: PRO-37 Scanner Modifications (Long)
Date: 24 Sep 91 13:32:11 GMT
Organization: Spar Aerospace Ltd, Toronto, Canada
MODIFICATIONS FOR THE PRO-37
The disassembly instructions are based on the excellent PRO-34 instructions
First of all, what modifications are possible?
The PRO-37 uses a diode array to tell its microprocessor what model it
is, and thus which frequency bands to allow and what channel spacing to
use. European and Australian models have full 800 MHz coverage (at an
unknown channel spacing) and a VHF-Mid band (68-88 MHz) rather than a
VHF-Low band (30-54 MHz).
The Canadian and US models differ in the amount of care taken to reduce
EMI. The Canadian model has additional screening, and one or two other
minor component additions to achieve this. Therefore, if you have the choice,
the Canadian model is preferable to the US model.
Changing from VHF-Low to VHF-Mid band coverage requires many
component value changes (and realignment of the appropriate RF stage).
Given that the PRO-37 uses SMT technology, it's not worth trying.
(You can change the diode array easily enough, but just don't
expect reasonable performance!)
The only sensible (straightforward) modification is the restoration of
full 800 MHz coverage on Canadian and US models. The ranges restored
appear with a 30kHz channel spacing - which just happens to coincide
with the N. American cellular telephone channel spacing. A remarkable
The modification described is therefore applicable ONLY to Canadian and
US models. (European and Australian readers could always remove
800 MHz coverage if they wished:-).
You will need:
Soldering iron - with a fine point. (The components desoldered
and soldered are not SMT, but ....)
Desoldering tool - to remove excess solder
Philips screwdriver - if it fits the screws on the back of the
case it's the right size.
Small pliers - bending component leads while unsoldering
and removing hexagonal posts
Earthing wrist strap - strongly advisable with CMOS components.
(Static can cause premature, if not immediate
failure of components). Wear this at all
Small screwdriver - for prying components etc.
Experience and confidence in working with modern electronics
A couple of hours without interruptions...
0. READ THROUGH ALL OF THESE INSTRUCTIONS BEFORE STARTING!
1. Remove the battery
2. Remove the antenna
3. Pull to remove squelch and volume knobs
4. Unscrew the 4***on the back of the case
5. Separate the case beginning at the battery end and work over the circuit
board and knobs at the top
6. Unsolder both connections to the antenna - ground can be bent away and the
centre has a link to the board
7. Unsolder the two power switch links at the board end
8. Unsolder the ground connections to the metal shield
9. Disconnect the two connectors to the squelch and volume controls
10.Remove 4 hexagonal posts
11.The top board may now be removed by separating it gently from the
connector on the adjacent board
12.Remove 3 screws holding the shield in place
13.Lift the shield to separate it from the lower control circuit board
14.Identify diodes D12,D13 on the control board
15.EITHER cut the diode D13 and SKIP to reassembly OR continue to
16.Remove last two screws and remove control board. Take care not to
dislocate the KEY LOCK switch when doing this.
17.Unsolder screening from side of control board near diode array,
and bend back out of way.
18.Unsolder and remove diode D13. Keep it somewhere so that you can replace
it if required to do so by US legislation.
Reassembly is the reverse of the above procedure.
If you performed steps 16-18 CHECK REALLY CAREFULLY that the metal part of
the KEY LOCK switch is in the right location. (Otherwise, you may find
yourself having to disassemble the whole thing again - I know, I did!)
1. One must exercise great caution in the procedure. Check that no flakes
of solder get dropped on the boards. Take anti-static
precautions by doing the work on a mat and wearing a wrist strap. Do
not make any adjustments to the upper analogue board or bend any of the
other wire links on it, which are tuned circuits.
2. Another caution is that doing any of the work will probably violate
any warranty you may have on the scanner. Might be worth burning the
scanner in for ~150 hrs before attempting this to reduce the risk of
a latent component fault appearing after you have made the modification.
3. YOU PERFORM THE ABOVE PROCEDURE ENTIRELY AT YOUR OWN RISK. You may
wish to obtain a copy of the PRO-37 Service Manual from Radio Shack
before attempting this. (Cost about $20 - well written - just wish
I could afford all the service gear required!)
4. If you happen to find out what adding D14 does (another difference
between N. American and European/Australian versions), I'd be
interested to know. It's not mentioned in the service manual. I think
it could affect 800 MHz channel spacing - any info on the European
Australian PRO-37 specs in this area would be appreciated.
5. If you found something wrong in the above instructions, let me know
and I will try and post an update.
6. If you found all this helpful, help someone else and donate $5.00
*today* to your favourite charity.
Share and Enjoy!
Subject: Re: PRO-37 MOD's
Date: 14 Dec 1992 16:14:44 GMT
Organization: HP Colorado Springs Division
This works. I have used this procedure to modify my pro37. One note:
there is no reason the remove the logic board. If you have skinny wire
cutters, you can easily get to the correct diode. This will save you
the trouble of getting the key pad and key lock back together properly.
Restoring the full 800Mhz coverage of the RS Pro-37 scanner.
The following notes have been shamelessly plagiarized from Mark Miller's
excellent instructions on modifying the Pro-34. The two scanners are
physically so similar that I needed to make only a few minor changes
in Mark's notes to make them fit the Pro-37.
The instructions below are for those that don't like to completely
dissassemble every new electronic toy they buy just to see how it
works. Nor is it for the guy that has been building their own equipment
since the days of the first tube diode. This set of instructions assumes
a moderate level of skill with a soldering iron, and some simple hand
tools. It is aimed at those who just want the additional coverage from
the mods but havn't been building kits for a decade.
lets just call these ....
"NOVICE NOTES" FOR PRO-37 MODIFICATIONS
1. Remove the 4 small phillips screws on the back of the unit
2. Remove the battery cover and battery holder from the case. You won't
loose your programming as long as you don't take all day to do
3. Remove the two knobs on the top of the case (Volume & Squelch)
4. The case snaps together at the bottom via two molded "hooks"
in the back half of the case which fit into two indentations
in the front half. These can be snapped apart by applying
the right leverage to bend the hooks away from the indentations
that they fit into while pulling the case apart. You'll see what
I mean when you look at it. You need to be a bit careful in
forcing the two halves of the case shell apart. Once you have
the snaps at the bottom released, angle up the bottom of the case
until the battery separation wall is clear of the internal metal
frame, and slide towards the top of the unit. Place the back half
of the shell aside.
5. Now you will see the RF board mounted to the metal support frame. The
BNC (antenna) conector leads and the volume control power switch leads
are soldered directly to the board. Carefully desolder these 4 connections.
7. There will be a wire from the volume control knob to the PC board that
is plugged in. Remove the plug from the RF board (needle nose pliers work)
8. There will also be a similar wire (small shielded ) from the squelch control
to the RF board wich is also plugged in. Remove the plug from the RF board.
(Again Needle Nose Pliers work good here)
9. Remove the 4 threaded hex stand-offs from the RF Board (these hold the RF
board to the internal metal frame AND are where the screws that hold the
back of the case***in) Use a nut driver or Needle Nose Pliers.
10. Now the RF board is mostly free. The only thing holding it in is
the row of connector pins on its botom side that plug into the logic
board. You will need to pry this board up gently. Be warned that
the bottom side of the RF board is just chock full of Very Small
surface mounted components. So use something non-metalic and smooth
to do the prying with.
11. Set the RF
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