Progress! I went through all your suggestions, and they were helpful. The results of the relay continuity test were just as the diagram showed. So, I checked the traces. The trace from the output jack to the relay goes through one of the pads of C17! When I pulled C17, both pads came off with it, so that broke the connection. After running a jumper wire from the output tip to the relay, the pedal again bypasses sound normally. However, as there is still no output in tremolo mode, I’m back to where I started.
I think the problem has to be the lack of voltage getting to the optocouplers. I tried to map the traces to see where those 5 volts @ R7/R8 originate from, but it’s too hard to see the traces with a populated board. Is there a diagram available that maps those traces? My board is version 8.3. I think this could make troubleshooting this issue easier. Or, can I just run a jumper wire from any 5v source to R7? I was going to try this anyway as a test, but I wanted to touch base with you first.
Thanks so much for your patience,
Peter