I'm feeling kinda free right now, so i figured i should ask myles....
Myles,
I have a small practice amp: A 1975 Peavey Pacer SS-100
I know it's solid state, and it's nowhere near the caliber of units you normally service, but the principles will still apply.
It's got some pots on the front (primarily the pre-volume and master-volume) that seem to have some `angry spots' in them.
I.e. if you gradually turn up the "master" volume, the sound will get gradually louder (as it should), until you get to a few positions where it will drop off to a whisper, and a few others where it will be as if you've got it cranked. Yet other volume positions it will just sit and make this really strange squeaky hum. (not sure how else to describe the noise).
I know dirt in the pots can cause the dropouts in volume (gets between the contacts and increases the electrical resistance) but in the case where a few volume positions are much louder than what they should be (an internal short in the pot?) could this also be caused by dirt and/or some form of conductive contamination? Maybe rust? (the amp sat in storage for about 2.5 years)
I've had the amp apart once before (fixed a broken wire in the reverb circuit) and it looks like all the pots are soldered directly to a (suprisingly small) circuit boad. Desoldering/Resoldering new pots in may be a bit beyond my abilities, and my guess is the amp is probably not worth taking to someone. A Classic Series yes, a Pacer, no.
Should i try to `clean' the pots with some of that aerosol spray stuff, or will this be difficult/pointless? Are they already shot?
Even though it's all i have at the moment, you won't hurt my feelings if you have to tell me it's beyond reasonable repair and it should be thrown away.
I greatly appreciate your time, Myles.