Premier 100r cutting out

[Chuck H]

Look at the schematic. The reverb channel mixes dry and wet signals via the bypass between V2a and V2b cathodes.

I did see that. But I misread (or misinterpreted) other circuit aspects. Brain fart.

[Helmholtz]

Does this help?

Yes it does and makes sense.
So these stages are actually supplied from the same PS node and the switch either disconnects V2a or V3b from its supply to slilence the respective channel.
Please see where the 10µ filter cap connects to the power supply and measure the V3b plate voltage in both switch modes.

[pontiacpete]

Ok I have to wire the switch back to where it was before like in the picture.

[pontiacpete]

With reverb off V3B plate is 60vdc and when switched on it’s 0vdc. Pin 6 of V2 there’s 50vdc with the reverb turned on and 0 when off.
Oddly enough I can’t get it to oscillate and turn off. This happened yesterday and I thought I was done. Tried it this morning and touched pin5 of the 6eu7 and it turn off the signal. I’ll keep checking it at this point. Also the cap on that pin, pin5 of V2 is still fairly microphonic.

[Helmholtz]

With reverb off V3B plate is 60vdc and when switched on it’s 0vdc. Pin 6 of V2 there’s 50vdc with the reverb turned on and 0 when off

Looks about right with a supply voltage of 100V and means that both triodes are working.
Now does the 10µ cap connect to PS node E?

[pontiacpete]

Yes it’s node E 100V.
But node E is not the 10uf cap, it’s the 5uf. This voltage comes from the main power supply on the other side of the amp through the 47K dropping resistor

[Helmholtz]

I meant the 10µ cap from your drawing in post #15. Where exactly does this connect?

[pontiacpete]

I think this is it

[pontiacpete]

This amp is still unstable, going into oscillation and turning off. I ordered a couple of 6EU7s to finally see if that’s the issue. I’ll be back with the results

[Helmholtz]

Did the reverb switch ever work properly?
I think the wiring is a mess.
I would un-link the channel inputs (the link only makes sense with this awful switch wiring), and restore the amp to original without the reverb switch.
Then you could use a switch box before the amp to either use the dry or the reverb channel input.

[pontiacpete]

No the switch never worked properly. It would work sometimes then the amp would stop passing signal. I don’t know what the original wiring is supposed to look like. But splitting the channels is a good idea. Thanks I’ll mess with that after I get my tubes in

[pontiacpete]

Of course the new 6EU7s did absolutely nothing. So went on to try many things and finally I got to the 470K resistor on pin 5 the grid of the 6EU7 where the .01uf cap that is very microphonic. I started subbing in resistors in place of the 470k and started with 1K. This reduced the reverb a lot, but maybe too much. It was pretty extreme with the 470K. So far I’m settling on a 4.7K. Reverb level is better, actually more usable. I need to sit with this for a while