Super reverb clone

[Rockranger]

Hey guys,
   Friend of mine built a 1965 ab763 super reverb clone, complaint was low volume and he wanted me to take a look( I am no expert at all but have built a handful of amps). Turned it on checked bias of the 6L6’s it was 42ma between pin 8 and 1ohm resistor to ground. Proceeded to check all voltages (all tubes b+ etc.) all looked spot on with the schematic! Output tubes seemed quite hot but didn’t look out of the ordinary, after 3 or 4 minutes of voltage checks I checked bias again and it read 163ma!!!! Flipped off standby immediately and grabbed my other meter, flipped it on for a sec and it read 163ma on that meter too, turned it off right away. Any suggestions on what this could be or what his next steps should be so nothing more is damaged

[shooter]

different tubes
ohm both halves of the OT primary to ct
verify G2 resistors

[sluckey]

What is the voltage on pin 5 of each 6L6? Check in standby mode.

[Rockranger]

In standby mode each 6L6 is -48.2v Pin 5

[sluckey]

Now check pin 5 while the tubes are running that 163ma. Be quick.

I'm pretty sure those tubes are toasted.

[Rockranger]

Thanks for the reply’s guys. Oddly enough after several attempts I was not able to reproduce this scenario again, the bias reading is holding steady at 42ma! I have a fresh set of 6L6’s here I think I will put them in and monitor closely.

[Latole]

Thanks for the reply’s guys. Oddly enough after several attempts I was not able to reproduce this scenario again, the bias reading is holding steady at 42ma! I have a fresh set of 6L6’s here I think I will put them in and monitor closely.

Bad solder/ connections ? 

[Rockranger]

New tubes seems to have fixed the bias problem I was having with this amp. Replaced OT in this amp and it has fixed the low volume issue but I am getting noise no matter which way I put the primary OT leads. One way I have a super high squealing sound, reversed them and now I have a out of tune radio lower squealing sound, any suggestions?

[PRR]

So this amp has never worked right? Suspect everything. Get a supposed schematic and compare to as-built reality with a hilight marker. Don't assume, be dumb.

[pdf64]

New tubes seems to have fixed the bias problem I was having with this amp. Replaced OT in this amp and it has fixed the low volume issue but I am getting noise no matter which way I put the primary OT leads. One way I have a super high squealing sound, reversed them and now I have a out of tune radio lower squealing sound, any suggestions?

Remove all the 9 pin valves, does that stop the noise?
If so, try it with the valve fitted in V6.
If you get a noise then, the OT leads to the anodes need swapping around.
If no noise, try fitting the valve into V1. The amp should work on the normal channel, which generally doesn’t have enough gain to become unstable.

[Rockranger]

Decided just to redo the power section in this one and it seems that all issues are resolved!