Got a 6505+ on the bench.

[StratTone]

The customer ran the amp with no load and blew a fuse and saw a tube light up. I put new tubes in and changed the fuse and the bias readings are much higher. 50ma on lowest setting. I have changed the bias resister on this amp before and had it set for 32ma last time I worked on it. The Peavey site seems to be down so I can't get to the forums for a schematic but was wonder what resisters control total current for all the power tubes? The screen grid resister must be fine since each tube does have current on them but it is drawing lots more current than it did before. Thanks for any tips.

[Amp Kat]

Follow the purple wires from the power supply to the reverse diode then two 10uf 160 volt e-caps and you'll see a resistor I think it's 15k going to the 220k bias resistors. That 15k is it and inserting a pot would be the way to go even if it's just a little trim pot would work good. Sorry don't have my schemos.

[Enzo]

I would be suspicious of it needing another bias mod. Assuming there is proper B+ on ALL pins 3 and 4, then what is the actual bias voltage at ALL the pin 5 grids?

The PV forum will tell you to contact the parts department at PV for the schematic, they'll email it for free. It is identical to the 5150-2, which should be easy to find, but PV would send that one as well.

Are you sure the output transformer was not damaged? That is what arcs when driven without loads often as not. And shorted turns there could mess with your currents.

How are you measuring tube current? Are all four tubes measuring the same?

[StratTone]

I measured current with my Bias Rite meter. They were all 50ma. I took the PI tube out to test it and it lit up in my tester but then tested fine. I put a new PI in and the bias levels returned to normal. Just to test I put the old PI back in and the levels looked fine now.......... Anyway I ditched the original PI and put the new one in and played for a while and all seems good. I didn't charge anything but told him to let me know how it goes. I usually do stuff like this for fun and not money.