Peavey Classic 30 really hot!

[Oldmactech]

Acquired a recent Peavey Classic 30 II (Chinese made) that had a failed transformer. At least the thermal fuse failed.
I replaced the transformer and the 12ax7 tubes and all is well. Sounds fine.
Yesterday I did a short recording session and tracked guitar for about 45 mins, normal volume not dimed ever.
Dang this thing is hot. The metal surround under the pots was nearly too hot to touch. This thing is a small combo but has 4 El84’s and 2 12ax7’s so I guess I would expect it to generate heat but this was over the top. Guess I know what took out the transformer.

Any cure or something to suspect would be generating excess heat?

thanks.

[Jon Snell]

Check the primary voltage tapping is correct.
R64 must have at least -14volts across it.
Here is a mod done on a few.
Replace R63 with 39k. Remove R64 and fit a 22k resistor with a 10k preset to allow adjustment.
That should reduce the heat.
Here is an example;

[The Dude]

And do check bias current. You may have one or more output tubes drawing excessive current.

[drewl]

I always add a bias adjust circuit to these and Fender Blues Jr's.

Did one of these yesterday, the metal around the tubes was discolored from heat, and it had a blown output tube.

Bias was hot, now it's not.

[Oldmactech]

Thanks for the replies. I have been unable to obtain a schematic for this version. This one has a mother board and daughter board and is different from the Classic 30’s with the boxed PCB config. (Sorry, poor description).
I’m not experienced enough to follow the bias instructions unless I can see the schematic.
Peavey has never responding when I asked them for one.

Anybody have access?

[TomCarlos]

If this is not the correct schematic, please post a couple photos of your pc boards.

Peavey Classic 30 Schematic

[g1]

The new version made in China is less than 10 years old. A schematic for it will be dated 2012 or newer I would think. It no longer uses the 3 sided 'box' board assembly.

[The Dude]

I wouldn't think you'd need a schematic to check bias- maybe to modify the bias circuit if necessary. Check it first to see if there is actually a problem. You can check bias by using the OT resistance method. Are any of the tubes redplating?

[Oldmactech]

Thanks.I think the schematic is from a previous version, the 3 sided box. Not seeing any red plating, all the tubes seem to glow normally. One of the designs problems is the tubes are surrounded by a metal cage which doesn’t really help air get to them. Makes troubleshooting harder also.

it would be really helpful if you would provide the “talking to grammar school kid version” of the resistance test at the OTs.

thanks again.

[The Dude]

It's explained here:

https://robrobinette.com/How_to_Bias_a_Tube_Amp.htm

Scroll down to:

"Measure Bias With the Output Transformer Resistance Method"

[Enzo]

Schematics: customerservice@peavey.com

[Oldmactech]

Thanks Enzo, I’ll try again (4th time I’ve emailed).

[g1]

Thanks Enzo, I’ll try again (4th time I’ve emailed).

Any chance your email provider is putting response in 'spam' or 'junk' folder?

[Oldmactech]

OK! Peavey finally sent the schematic.
no excuse now.....

[g1]

Please post it here.