Ampeg J-12B

[KingCameron]

I have recently acquired an Ampeg J-12B, that has a hum at almos all volume settings. I am suspecting the multi-section cap.

The cap installed in this amp is a 20/30/20, however the "free" schematic I downloaded for this amp indicates a 20/20/20.

Can someone confirm what is actually correct for this amp?

Also, a better schematic would be super cool, if anyone has one.

Thanks,
Cameron

[Sock Puppet]

I'm unsure of the "correct" value for that capacitor (it won't make alot of difference) but there's a clean version of the schematic at www.schematics.ca

Here it is:

S.

[KingCameron]

Ampeg J12-B

Thanks Sock Puppet!

I actually have that particular schematic, but was concerned as it shows the cap to be a 20/20/20. The amp I have, has a 20/30/20 in it.

I went ahead and purchased a 30/20/20/20, so I will try both wiring configurations, should need be

Thanks again!

[Enzo]

Like he said, the different cap value won't make a difference. The extra 10uf on the one section would tend to work slightly "better" than a 20.