software

I have a marshall jcm 2100 slx, with 2 channels, the only difference is the volume, so the purpose is to have 2 different volumes. On the second channel when I switch to it from the first channel with a crate footswitch pedal. Once I do that and adjust the volume it makes squeals, has volume drops, just plan doesn't work well.

Do you guys think it could be a dirty pot, broken pot, or the problem is the crate pedal I'm using to do the channel switching? I have tried the techinique where you spin the knob a bunch of time to try cleaning the pot a bit, but it didn't work.


Originally Posted by greendy123I have a marshall jcm 2100 slx, with 2 channels, the only difference is the volume, so the purpose is to have 2 different volumes. On the second channel when I switch to it from the first channel with a crate footswitch pedal. Once I do that and adjust the volume it makes squeals, has volume drops, just plan doesn't work well.

Do you guys think it could be a dirty pot, broken pot, or the problem is the crate pedal I'm using to do the channel switching? I have tried the techinique where you spin the knob a bunch of time to try cleaning the pot a bit, but it didn't work.

Dirty/broken pot is my first thought as well.

Do you guys think it could be the pedal, cause a guy at one of the guitar shops I go to I asked and he said that could be the problem.


Originally Posted by greendy123Do you guys think it could be the pedal, cause a guy at one of the guitar shops I go to and he said that could be the problem.

The best way to test that is by getting another pedal. Can you bring it into the shop and test it there or borrow a pedal from them?

I highly doubt it's your pedal. I have the MkIII 2100 (predecessor to yours) and use a homemade footswitch made with a Hoover vacuum cleaner stompswitch and have no problems at all with Master B. Take it to a good shop and have them check out that area. I bet it's the pot too.

Do you guys know what value I should be looking for a small fix like this? I asked before at a guitar store and they said around $20 /- $10 for something like that. What would guys say would be a okay price for a job like this?

From the schematic I'm looking at it's a 1M Log pot.

Do you guys think it could be the pedal, cause a guy at one of the guitar shops I go to and he said that could be the problem.

I'm certain there's no way it could be the pedal. Whatever company name is printed on the case, it's just a DPDT switch in there. They're all the same.

Sorry for being slow on this but I don't really understand your problem. Are you saying the two channels sound the same? And one is far more prone to feedback?

The first channel quot;Aquot; is fine, but when I switch to the second one quot;Bquot; with my footswitch it was weird sounds either really low, pops, squeals, then weird noises come when I turn the quot;Bquot; channel's knob.

It's the pot or some other component that it connects in with. There is an IC chip right where it connects to but my initial thought is the pot. Simple fix.

BTW, the MkIII and MkIV JCM900 Master Volumes are single channel amps with switchable master volumes, with master B giving a boost. Just want that to be clear.

Anyone here around Rochester know of any good amp techs? I'd like to stay around the Henrietta area by the Marketplace Mall.