66' twin

[chris61]

JoeM,
thanks for the reply, I think I see the one you mean.
But in my amp thats a 50uf not 100
and the schematic shows 50 as well
but maybe I'm reading it wrong?

[Enzo]

Yeah and some older schematics show bias filter caps as low as 2 or 4 or 8uf. A 100uf filter will make the bias even less hummy than a 50uf cap. Use the 100. The 100uf will be better, and the 100v will be safer.

If you read some Fender schematics, you will see right there in black and white, the bias filter cap is 50v rated and the voltage in the supply is 55v. And yet it lives. Look at the Fender Twin Reverb AB763 schematic.

[Jazz P Bass]

I just had a Fender Pro come in with the same symptom.
Crackly noise in Vibrato Channel when the cab or chassis is tapped.
Found the Vibrato Channel 0.1uf 600V coupling cap was bad.
Guy had it to two other shops.
Tried to explain an intermittant can be tough to find.
I found it with the chopstick.
When I tapped on that particular cap, it made noise.