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Old 27th May 2012, 04:17 PM   #1
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Join Date: May 2012
Default Need cap help for Adcom GTP-600 Tuner/Pre-amp

When I got this GTP-600 it would only tune stations 105 thru 107. I found a helpful post that said that the culprit was often variable capacitors CT101, CT102, CT103, and CT104 (indicated with red arrows in attached image). Indeed, after turning them back and forth and using some DEOXIT, everything immediately began to work perfectly. However, every couple of weeks the tuner fails again, and I have to take the cover off and do the same procedure, turning them back and forth, and using DEOXIT. This has been going on for a couple of months now.

Any ideas of what might make the fix longer lasting, or do I just need to replace them? And, would it be likely that I could find the exact same caps through a supplier, to make it easier for me to swap them out?
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Old 27th May 2012, 06:14 PM   #2
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Location: Oneonta, NY; USA
I would suspect a bad solder joint somewhere in the neighborhood of the trimmer caps. Can you get at the bottom of the board and "touch up" the connections (look first and see if you find anything "suspect"

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Old 27th May 2012, 06:19 PM   #3
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Yes, I should be able to do that. I will make it the next thing I try. Thanks.
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Old 28th May 2012, 02:55 PM   #4
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DeOxit is wonderful stuff and I use it on everything except the wife .....

But it isn't the tool for this job. You need a "tuner cleaner" that leaves no residue at all. Variable caps are susceptible to any sort of contamination.
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Old 7th June 2012, 05:06 PM   #5
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The GTP600 stopped working again, so I used that opportunity to remove the circuit board and touch up the solder connections for the caps. Put the board back in, without rotating the caps or etc., and it has all worked fine since. So, hopefully it was just a broken or cold soldered connection, and the problem will not happen again. I have really liked this tuner.
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Old 5th February 2014, 02:35 PM   #6
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Location: Largo, FL
THANK YOU penr0295
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