Marshall JCM2000 DSL100 - Channel Switching Popping Noise

[bw1985]

Hey all,

I've got a Marshall JCM2000 DSL100 head with the dreaded "popping sound" while switching between channels. I'm sure this has something to do with a capacitor in the power supply but nothing is visually looking problematic. I'm going to start digging in and taking measurements but just wanted to see if anyone has encountered this issue before and perhaps solved it?

All tubes are tested and good to go, and this issue is occuring while using the front panel pushbutton switches. I've tried with and without the effects loop and reverb in the circuit and the issue persists.

Thanks in advance!
-B

[rockinjeff7@gmail.com]

Hey all,

I've got a Marshall JCM2000 DSL100 head with the dreaded "popping sound" while switching between channels. I'm sure this has something to do with a capacitor in the power supply but nothing is visually looking problematic. I'm going to start digging in and taking measurements but just wanted to see if anyone has encountered this issue before and perhaps solved it?

All tubes are tested and good to go, and this issue is occuring while using the front panel pushbutton switches. I've tried with and without the effects loop and reverb in the circuit and the issue persists.

Thanks in advance!
-B

Did you solve the problem. I am having the same problem with my JCM2000 DSL100H.

I mostly only have it going from overdrive to clean when a note or chord is still playing. Don't hear it when changing channels without any notes still playing.

It's very difficult to transition without it while playing. Have to mute the strings before switching to clean.

[Mars Amp Repair]

Hello folks,
I had a -DSL JCM2000 50watt version with this issue. There seems to be no schematic that matches the boards in this particular version of this amp.
The issue was 2 shorted/leaky silver mica 470pf caps C19 & C20 on the front PCB. They are fed from p1 plate of V-3 on the main board, thru CON9 on main to CON11 on the front pcb down near the bass control. See attached.

[Mick Bailey]

I've had this problem a few times with Marshall amps. I replace the caps with the resin-dipped 1kv ceramic with no further issues.

[Mars Amp Repair]

I didn't notice what the voltage rating on the original caps is, but it almost seems like they must have been rated too close to the voltage they were exposed to. As I recall it was around 240v fed thru the 100K plate load resistor of V-3. I suppose they could have been under-rated at 200V.
The silver mica's I used were 500pf @ 500V. Doubtful they'll ever have any further issues.
Thanx, glen