JCM 2000 DSL 401 dual super lead pots

[toto207]

Hi All,

Returning to playing after a while and my JCM 2000 - DSL 401 amp isn't working at all. There is a horrible crackling noise when any of the knobs are turned, though it's making the volume knob. After reading around, I thought it could be the pots inside the amp. So I managed to remove the cabinet which contains all the hardware/electronics however there doesn't appear to be the potentiometers I've seen in other posts, just these green chips therefore I'm not sure how I can clean/fix this issue.

I've attached a picture.

Any help would be appreciated,

Tone

 

[toto207]

* the volume knob makes the worst crackling noise...

 

[Tatzmann]

These green "chips" are the pots.

Garbage pots!

Good luck cleaning them efficiently like with a conventional pot.

The DSL's, along with most new consumer gear belong to the type of gear that if it fails, youre supposed to trash it, or huge parts of it. In your case the pcb that holds these sorry ass excuses of potentiometer.

They just want to change the whole board and trash/recycle instead spraying a little bit of cleaner inside the pots to make it work again.

Try googling "cleaning korg potentiometers" or something like that, there is a solution.

 

[Tatzmann]

And here is one out of my book:

"One turn a day keeps the crackle away!"

 

[JohnH]

I think that due to the way the circuit feeds the power-tube bias through the wiper of the volume pot, its vulnerable to getting a crackle when it moves. Annoying yes!

These green 9mm pots are hard to feed cleaner into, but I got some relief on mine by a good squirt from the front having taken the knob off, and from the back, and then turning the pot a few times. I think lubricated contact cleaner is best. Somehow, a bit of cleaner got inside.

Its worth a try. I had some serious pot issues on mine a few years ago, but only did as above and its pretty much ok now, after almost 20 years Ive had it.

 

[Leonard Neemoil]

Stewmac makes a fitting that screws onto the front of guitar pots so you can clean them without taking the control cover off. Not sure if it fits the pots on your 401 though.

I was going to post the link for you but they must be having a problem with their site right now because I couldn't access it the few times I tried.

 

[tmingle]

I manged to find all the pots at Newark a few years ago, but I can't remember what the part numbers were. I still have a couple of the 200K MV pots in my stash. I replaced them with Panasonic pots.

 

[tmingle]

If you decide to proceed, I highly recommend replacing these pots. The bias voltage for the power tubes is routed through the MV pot. If it fails the output tubes will red plate.