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Question for technicians

Recently I noticed my system was sounding dull and flat. Then I discovered there was little to no sound out of the right speaker, just an intermittent weak signal accompanied by static. Later, I noticed that I could make the signal come and go by merely touching the preamp's input selector switch, or applying a slight push-or-pull pressure to the control knob. I don't have any audio shops around here that I trust and I can do simple things like solder touch-up, continuity checks with a vom etc... Any ideas of how to go about checking this out? (greatly appreciate any and all advice)
rawinsonde

Showing 4 responses by atmasphere

atmasphere's avatar
atmasphere
12,088 posts
 
Use the Radio Shack contact cleaner first! The ProGold can cause trouble in some circuits (I've seen it contaminate circuit boards to the extent that they had to be pressure washed to remove the ProGold)!! IMO/IME the Radio Shack contact cleaner is the only thing you want to use as it is safe with just about any circuitry, especially if vacuum tubes are involved.
atmasphere's avatar
atmasphere
12,088 posts
 
*Sparing* use of Deoxit (DN5) will work fine. Keep it away from circuit boards if you can. Its more powerful than the Radio Shack cleaner and tends to have more capacitive effects (although slight) from what I can tell.
atmasphere's avatar
atmasphere
12,088 posts
 
If you can't get to the switch itself then the cleaner is likely not going to do the job by trying to get it to go through the shaft bushing for the switch!

Your best option at this point is actually pretty simple- operate the switch vigorously to both limits about 50 times and see if it gives you any trouble after that. The only reason its a problem is corrosion from lack of operations.
atmasphere's avatar
atmasphere
12,088 posts
 
I work on vintage electronics a lot. The better stuff frequently have 'J pots' in them- Allen Bradley J-Style potentiometers. They are really well sealed. If they get noisy, the technique above actually works fairly well on them unless they are really far gone. In that case you have to drill a small hole in them which is really dicy, but at least then you can clean them.
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