problem with pro 2004

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petetong

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Mar 24, 2008
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hello new to this forum. and hoping some one can help.
just been given a pro 2004. thats got a fault.
if you turn it on it powers up. as in the screen lights up but no numbers in screen.
the key pad works and beeps as you entry in numbers. if you entry in a wrong channel it double beeps as it should do when the error display would light up.
there is nosie coming out the speaker, but it not radio nosie!
the dim button works but the squelch does'nt work and neither does the sound squelch button work.
the set looks to have had very little use so it whould be a shame to just discard it!!
any one got an idea??does it sound like a fault the unit suffers from?
 

dste

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Bob Parnass once put out a tip that you might check...If your PRO-2004 is completely dead, check R235, a 1 ohm, 1
watt resistor mounted vertically on the main board.

Good Luck
 

pro92b

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Here is a short file I put together regarding PRO-2004 repair. The printed circuit board problem referenced near the end of the text is the most common failure. I've repaired several PRO-2004's with this problem and it can take up to 40 hours to redo all the connections. In general it isn't worth the time to get a dead PRO-2004 going again. Since your unit does power up the 1 Ohm resistor is not the problem. You might consider selling the radio for parts either here in the classifieds forum or on Ebay.

-------------------------------------------

Repairing the PRO-2004 Scanner
The PRO-2004 radio scanner was made for Radio Shack by GRE, a Japanese electronics company. Introduced in late 1986, nearly 45,000 units were made by the time production ended in early 1988. An instant classic, the PRO-2004 was head and shoulders above any other scanner made when it was introduced. Even today it is one of the finest scanners available for conventional scanning.

One common problem with the PRO-2004 involves the memory backup battery circuit. Sometimes the low battery warning keeps activating even when a fresh battery is installed. Memory loss when the radio is unplugged is also a symptom of the same problem. The tips from Bob Parnass listed below are a good place to start to fix this problem.

Make sure the contacts on the battery connector are tight. The snaps widen and lose contact, and you can squeeze them gently with a pliers to tighten them.
Unplug the AC cord from power and remove the battery. After a few minutes, insert a good battery, plug the power cord back in the wall and perform a full reset according to the instruction manual.
Check the through-board solder joint at connector CN6, pin 3. Some owners have reported a bad joint there.
In addition to Bob's suggestions, be sure to check the wires from the battery connector to the printed circuit board for continuity. Use an Ohmmeter to be sure the connection is good.

If a new battery goes dead after just a few days, it is likely that the memory regulator has gone bad. The regulator is in a TO-92 package and looks like a small transistor with three leads. It is labeled IC9 on the printed circuit board. The part is made by Seiko, type S81250HG. The Radio Shack part number is 10889566 although it may no longer be available. Part number 628-812C50AY-G, available from Mouser Electronics, may be used as a substitute.

The PRO-2004 had serious quality problems with its printed circuit boards, especially during 1987 production. There are copper traces on the top and bottom of the boards. In places where it is necessary to connect top and bottom traces together, a hole was drilled and then plated with copper to make the connection. This plating was faulty and over time it cracks, breaking connection from top to bottom. The symptoms can range from corrupted memory to the squelch not working. Sometimes the problem comes and goes or may be sensitive to temperature. The only way to permanently fix the problem is to put wires in all the holes and solder the connections on top and bottom. Pop the tops off the shields and repair the connections inside too. This takes a huge amount of time and for this reason repair shops like G&G consider the PRO-2004 to be unrepairable.

Another problem involves the glue GRE used on the large power supply capacitors to secure them to the main PC board. It's often black in color and you should see it around the base of the capacitors. There is a corrosive element in the glue and given enough time it eats through the copper on the PC board. The glue can be scraped off the board with a toothpick (don't use a metal tool) and you can then assess the amount of damage due to corrosion. Repair any broken traces with small lengths of wire.
 

petetong

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Mar 24, 2008
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so is it that the pc board has got bad (dry)joints???
if thats the case would it be more than likely to be just one off the boards? as some off the unit is powering up. if thta does sound right, anyone have an idea which board it might be??working from the systems i have given.
 

pro92b

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None of the radios I repaired had bad solder joints. The defect is in the copper plating in the feed-through holes. Trying to use solder to fill the holes isn't reliable and can't be visually inspected for continuity. That's why I put small wires in the holes and soldered them top and bottom. Every radio I worked on had problems only on the large main board. Some radios had multiple failure points so I ended up shot-gunning the repair by doing all the holes. The epoxy ate through a conductor in one case as well. As you can imagine, all this work is very time consuming.
 

petetong

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Mar 24, 2008
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so when you say the large main board you mean the board on top as you take the cover off?
and all so when i did take the cover off there was a 3 prong resister that had been unsoildered. and moved to one side. it was fixed with a screw to an alloy heat sink on the fare left hand side off the board. just below it was an other one but it was still fixed to the board.
the unsoilered one had .T 01 40g
oR'7j on it??? and was soilered on to the board at Q32..
can any one tell me why it had been taken off?a mod off some sort??
 

pro92b

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Q32 is a 2SD1406 transistor which is part of the 8.4 volt regulator. It runs much of the circuitry in the radio and shouldn't be disconnected. Evidently somebody monkeyed around inside the radio and that will make servicing even more difficult. If you still want to pursue it, join the PRO2004 group at Yahoo.com and download the service manual from the files area. It has schematics, a parts list, and PC board layouts, all of which you will need to undo whatever problems the previous owner caused.
 

petetong

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Mar 24, 2008
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right i am thinking that the 8.4 voltages regulator at Q32 is the problem.
the rs part number is.2SD-1406 (GR) (NPN).
does anyone no a part number of an equivalent replacement.??and best place to get one?
(here in the UK)
 
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I just recently got a mint Pro-2004 ( date code 11A7) on Ebay and it had many problems. It would sometimes take a program but insert a different freq once I hit enter, and it would insert the same freq about 4 channels later. It didnt receive anything, not even wx which is strong here. Found this thread on google and took the cover off. There appeared to be a few solder blobs on some of the "hole thru's" but nothing major, it was actually really difficult to see if anyone tried to rework it.

Fortunately I had an old 2004 that I bought originally when they closed them out (date code 6A7), which still works! Because the problem seemed to be cpu related, and because it was the easiest thing to try, I switched the cpu boards and the problem moved from the new scanner to the old scanner. So I guess it can be the cpu board, not just the main board.

I've left it at that for now, nice to have a working backlight! This scanner probably had problems early on, which is why it looks like new and the backlight is bright. I will try to rework the other cpu board when I get time. There are some hole thru's under the main chip, but I think I can jumper them all with help of the service manual found here:

http://www.dream-machine.myzen.co.uk/Radio Shack - Realistic/PRO-2004 (Service Manual).pdf
 
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