Hello,

I own a JMP 2204 from 1980. Today when I switched it on (after the warm-up phase) I suddenly noticed a strong change in pitch, the sound became duller. When I tried to change the treble control, I noticed that at 10 the sound was completely gone and at 0 it was the loudest. However, there was no change in the pitch. I swapped the V2 for another ECC83, no difference.

What could this be?What to do?

Thank you very much!