Replacing amp pots?

[Burn]

I have an old Mesa 50 cal+ head, and the Treble Mid and Bass pots don't seem to work.
I've been using the separate slide eq control for awhile now, and the amp operates just fine. I'd like to replace those pots, and be able to run the amp both ways though. Is there anything I need to know that might be different from wiring guitar pots?

[DonP]

With all three pots no working, maybe it's something other than the pots? In a Marshall tone stack, I think the bass pot is grounded, and the other pots connect to it. Remove the ground, and it acts like there is no tone pots at all.

Other than that, I think Mesa's have pots soldered onto the board, so it's a PITA. I have an 80's Marshall Micro Stack, of which all of these are known to have scratchy pots (or maybe voltage going through the pot - a big no-no). I love this Micro head, so one day I'll pull it apart and put in some high quality pots, if that's the fix.

[Burn]

That makes sense. I followed everything back, and it seems solid. I should note that I do get some sound changes while goofing with the pots, so that is why I assumed they were bad. I think I'm going to pull the whole board out and check everything over.

[SweetPete]

Before replacing any pots, try cleaning them with this stuff:

http://tinyurl.com/2hn6p5

I use it, and swear by it. Works fantastic - I've used it to restore noisy pots to new (quiet) condition.

[Burn]

Well see, they aren't actually noisy, it just seems like the amp doesn't respond to them. I've contact cleanered, and checked every connection I can find, but I think there was a repair on this amp, and it must have been a good one, because I can't find it.

[Burn]

Still scratching my head over here, normally, if I'm working on an amp and I hit a roadblock, I head over to the geofex site, and I can find at least good direction. It seems like the amp doesn't want to respond to the eq pots, although it responds to the slide eq fine. Master volume works, Gain works, the lead master pops but works, I assume it's a resistor and unrelated. I've gone over the the small amount of wiring from the pots to the board, and followed the circuits back checking for shady looking solder, and nothing. I suppose I could break it all down, replace all the pots, and give it a full cap job, but I play the thing all the time! Sheesh.

[patricef]

I'm not familiar with amp schematics but it could be than one dead pot can ruin the tone circuit:

http://www.freeinfosociety.com/electronics/schemview.php?id=504

What can be suspiscious also is the optocoupler LD3. Mesa uses a lot of those Vactec and they tend to fail frequently.
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