Back from the dead :shock:
Well, it so happens that I have been working on refurbishing a GA-30RV that had been severely butchered. Some previous owner had apparently tried turning it into something like a tweed pro...it was a real wreck. Non-original and incorrect OT and PT, totally different filtering and back end. And the work was really a thing of ugliness as opposed to beauty. So I've been rebuilding this, taking it back, pretty much, to stock. New PT and OT (hammond), all new filter section, cathode bias, new filament wiring, etc.
The pre-amp appears to be completely original and per the design, but the reverb circuit on this one is also messed up, though not exactly like the one in CJ's earlier posts. The circuit in this amp differs in some other ways. Here's the original schematic.
And here are the parts of the reverb circuit on mine that differ. The wiring sure does look original though...it's ancient and appears untouched.
Note that the input to V2 pin 5 comes not from the plate on pin 7 of V1 but from the output of the Ch 2 vol pot. So there is no Reverb dwell pot in front of the reverb transformer and pan. Instead, this pot is located at the other end of the reverb pan, leading into pin 5 of V3!!
The reverb is there...but it's weak sounding and hums if you turn it way up, as does channel 2. So I'm going to try taking this back to the original design.