Ham Radio 2000 #1/Ham Radio 2000.iso/ham2000/scanner/mods/pro37.mod

Internet Message Format | 1993-11-04 | 16.4 KB

From: [e-mail] (Mike Bell)
Newsgroups: rec.radio.shortwave
Subject: PRO-37 Scanner Modifications (Long)
Message-ID: <[e-mail]>
Date: 24 Sep 91 13:32:11 GMT
Organization: Spar Aerospace Ltd, Toronto, Canada
Lines: 143

MODIFICATIONS FOR THE PRO-37
----------------------------

The disassembly instructions are based on the excellent PRO-34 instructions
provided by Chris Scholefield ([e-mail]). I have added my own
comments.

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
coincidence.

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
                  times.
    Small screwdriver    - for prying components etc.

    Experience and confidence in working with modern electronics

    A couple of hours without interruptions...


Instructions
------------

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 screw 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 desolder diode

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!)

NOTES.

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!

-- Mike -- <[e-mail]>


From: [e-mail] (Tom Vervaeke)
Newsgroups: alt.radio.scanner
#Subject: Re: PRO-37 MOD's
Date: 14 Dec 1992 16:14:44 GMT
Organization: HP Colorado Springs Division
Lines: 207
Message-ID: <[e-mail]>
References: <[e-mail]>
NNTP-Posting-Host: itchub21.cs.itc.hp.com


==================================================================


                         PRO-37

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
    this.

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 screw 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 board aside.

12. The Internal Metal support frame is now exposed. there are 3 small phillips
    screws holding the metal frame to the bottom Logic board (actually, these
    screws go through the logic board and into the front half of the case)
    2 of the screws are near the top, and 1 is at the bottom of the metal frame.
    Remove these 3 screws.

13. There is a small socketed wire that leads from the small power pc board
    on the metal frame that goes under it and is plugged into the Logic
    board.  Lift the metal frame up and remove the power plug from the
    PC board. Place the metal frame with the rest of your parts pile.

14. You have the component side of the  Logic board exposed now. There are
    2 small phillips screws at the bottom of the PC board (where the Battery
    compartment WAS) Remove them.

15. Once you have the the last 2 screws removed the Logic board is free. The
    speaker wires lead from the speaker to the logic board on the bottom side.
    These are soldered in but there is enough play in them to allow you to
    make the mods.

16. NOTE: The keyboard lock switch is a funky little piece of plastic with
    a sliding stainless metal contactor that is just wedged in between the
    front case and the logic board. Remove both the switch contacts and the
    plastic switch. (best know it now or loose them in the carpet)
    ALSO: don't touch the innards of the keyboard itself, which will now be
    exposed.  It appears that the keys make direct contact with pads on the
    circuit board, and you don't want grit and skin oil to be getting in there.

17. On the component side of the PC board you will see lots of nifty surface
    mounted components, a box-like capacitor (used for maintaining the
    channel freqs while you change the batteries.. and make modifications :)
    near the edge of the PC board you will see a couple of small diodes mounted
    vertically. These will be labeled on the PC board as D12 and D13. You will
    also see places for two other diodes to be soldered in (labeled D11 and
    D14) but nothing is installed in these.

18. Now carefully clip the lead coming from D13 and bend the
    diode away slightly to make a gap between the resulting two pieces
    of wire.  Clip it near the middle to leave plenty of room to resolder,
    in case you ever want to undo the mod.

You have completed the mod for complete 800mhz band coverage.

Follow the same steps backwards (18->1)and replace "remove" with "replace"
and "desolder" with "solder"

N.B. These instructions are from last night, All the steps are in correct order
as well as the general information. The diagrams are from memory so components
may not be in the exact location indicated, but they will be very close.

LASTLY, Now that you have made the mods, you can use the warranty card to
light the Bar-B-Q Grill with.


################################ DIAGRAMS #############################


       BNC Connector             RF Board
   __ /                         /       internal metal frame
    |- ============================= /
   --  |                            \                         Logic Board
       |_____________________________|                       /
      ===============================================================

              SIDE VIEW OF RF-BOARD, METAL FRAME, LOGIC BOARD

                                               ---------------------------------
                                              |        L E G E N D
                                              |---------------------------------
       _____________________________          |   X1   BNC lead
      | @                @         |          |   X2   BNC Shield Lead
      |_                           |          |   X3   Power Switch Lead
     --_X1                         |          |   X4   Power Switch Lead
      |                            |          |
     ---X2             __          |          |
      |                --1         |          |
      |                            |          |
      |                            |          |  _
      |         __                 |          | ( )    Channel Memory Capacitor
      - X3      --2                |          |  -
      - X4                         |          |  __
      | @                      @   |          |  --1   Plug from Squelch Control
      |____________________________|          |  __
                                              |  --2   Plug from Volume Contol
            TOP OF RF-BOARD                   |
                                              |   @    Threaded Stand-off
                                              |
                                              |   *    Phillips Screws
       ______________________________         |
      |*                     |    || |        |   0    Diode (vertical mounted)
      |                      |    || |        |
      |                      |____|| |        |   .    Unoccupied space
      |                            | |        |        for diode
      |                             \|        |
      |                             *|        |
      |                             /|        |
      |                            | |        |
      |                            | |        |
      |                            | |        |
      |*                           | |        |
       ------------------------------         |
                                              |
     TOP OF INTERNAL METAL SUPPORT FRAME      |
                                              |_______________________________

       --------------------------------------------------------------
      |                                                            *|
      |                                                             |
      |                                                             |
      |                           _                                 |
      |                          ( )                                |
      |                           -                                 |
      |                                                             |
      |                                                             |
      |                                                             |
      |                D12  D13                                     |
      |                  \  /                                       |
      |                  .00.                                      *|
      |_____________________________________________________________|

                 COMPONENT SIDE OF LOGIC BOARD




--
Happiness is being a cynic, That way everything Sucks.

10-92           Mark S.   [e-mail]




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