Gibson Tremolo

[wallyo]

I am attempting a restoration of a Gibson GA-50T and all is going well except for the tremolo circuitry. I have what I believe is a valid schematic but I can't work out how the tremolo circuit is supposed to work and hence I am having difficulty troubleshooting it.
I was expecting a phase shift oscillator but that doesn't seem to be the case for this amp.
One aspect that makes no sense to me is the second half of the 6SL7 - it has 51K B+ to plate and 51K cathode to ground. Does that not suggest that this tube is in cut-off all the time?

[loudthud]

I found the schematic at the Hoffman site. The date on it is 8-27-64. That circuit is really wacky. Does your amp match the schematic? I wouldn't be surprised to find that there is a mistake on the schematic, possibly intentional, to stop people from copying the amp. That 51K in the cathode of V7B doesn't make any sense unless the grid is biased above ground by 75V or so. And that switch around the 15K, is that the footswitch?

[wallyo]

I think we have the same schematic - same date anyway. I can't say for sure if the amp is wired per the schematic - certainly it is in most areas - but the tremolo area has been "worked on". I believe the switch shown is supposed to be the foot switch.
I'm trying to work out ways in which the schematic might be in error. I'm also trying to jam it into the "phase shift oscillator" form. If I can't figure this out I guess I'll have to just design one that works.

[wallyo]

I did a complete re-capping of the amp and now the tremolo works. I don't know exactly why it roks but.....
now, the caps in the tremolo circuit were unusual. The 0.1's were in grounded metal cans (no connection between the cap and the can). The .25's were in rectangular metal boxes with feed-through connections. The wiring to these parts was done with shielded cable. I used ordinary caps and no screened cabling. The tremolo waveform is not particularly nice and I can hear the oscillator when the tremolo is one and there's no audio input, but I figure its close enough at least for now.
So bottom line is that the schematic seems to be correct. Thanks for your input.

[pontiacpete]

what did you end up doing with the .25s?
I have one here now and I'm trying to get the trem working.
Do you remember what the voltages looked like on the plates of that 6SL7?
I'm only getting 5vdc.