Normal channel missing just mV of output, same with footswitch supposed operation, lead ch is fine. Seems to be a rare beast, any pointers to a schematic ? Uses 4x rc4558 opamps ,2x SJ3692 in PA, seems to use an opamp and FET for gating on and off "normal" gain channel. Swapped out the 4558s, as socketed, no change. Thought found prob on underside , one pot pin had never been soldered, just touching contact and some ring crack failures or dodgey looking at pots, but that was just the general crackly performance, clean ch still absent. o/p of one opamp is high, same with swapped version, goes to gate of the FET, which will be the next thing to investigate, if no schematic found. When last powered I did not think to see if the footswitch action gated the opamp o/p. Any other ideas?
- posted
7 years ago