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Date: 24 Sep 91 13:32:11 GMT. From: Newsgroups: rec.radio.shortwave. Subject: PRO-37 Scanner Modifications The Long Version. Organization: Spar Aerospace Ltd, Toronto, Canada. THE MODIFICATIONS FOR THE PRO-37 The disassembly instructions are based on the excellent PRO-34 instructions. Provided by Chris Scholefield chriss 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 id band 68 MHz to 88 MHz rather than a VHF ow band 30 MHz to 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 30 kHz 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. A 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: STEP 00. Read through all of these instructions before starting. STEP 01. Remove the battery. STEP 02. Remove the antenna. STEP 03. Pull to remove squelch and volume knobs. STEP 04. Unscrew the 4 screw on the back of the case. STEP 05. Separate the case beginning at the battery end and work over the circuit board and knobs at the top. STEP 06. Unsolder both connections to the antenna ground can be bent away and the centre has a link to the board. STEP 07. Unsolder the two power switch links at the board end. STEP 08. Unsolder the ground connections to the metal shield. STEP 09. Disconnect the two connectors to the squelch and volume controls. STEP 10. Remove 4 hexagonal posts. STEP 11. The top board may now be removed by separating it gently from the connector on the adjacent board. STEP 12. Remove 3 screws holding the shield in place. STEP 13. Lift the shield to separate it from the lower control circuit board. STEP 14. Identify diodes D12, D13 on the control board. STEP 15. Either cut the diode D13 and skip to reassembly OR continue to desolder diode. STEP 16. Remove last two screws and remove control board. Take care not to dislocate the key lock switch when doing this. STEP 17. Unsolder screening from side of control board near diode array, and bend back out of way. STEP 18. Unsolder and remove diode D13. Keep it somewhere so that you can replace it if required to do so by US legislation. NOTES: 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 can now it, I did that. STEP 01. 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. STEP 02. 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. STEP 03. 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. STEP 04. If you happen to find out what adding D14 does (another difference between N. American and European and 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. STEP 05. If you found something wrong in the above instructions, let me know and I will try and post an update. STEP 06. If you found all this helpful, help someone else and donate $5.00 today to your favourite charity. SHARE AND ENJOY 73 FROM MIKE From: tvervaek. Subject: The PRO 37 Modification. Date: 14 Dec 1992. Organization: HP Colorado Springs Division. MODIFICATION FOR THE PRO 37 This works. I have used this procedure to modify my Pro 37. 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 800 Mhz 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. HERE CAN YOU FIND SOME NOVICE NOTES FOR THE PRO 37 MODIFICATIONS: STEP 01. Remove the 4 small phillips screws on the back of the unit. STEP 02. 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. STEP 03. Remove the two knobs on the top of the case Volume and Squelch. STEP 04. 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. STEP 05. 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. STEP 07. 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. STEP 08. 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. STEP 09. 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. STEP 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. STEP 11. Set the RF board aside. STEP 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. STEP 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. STEP 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. STEP 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. STEP 16. 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. STEP 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. STEP 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 800 MHz band coverage. Follow the same steps backwards 18 to 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 modification you can use the warranty card to light the barbecue grill with it. |
