Strange noise coming from 1970's Gibson G30 solid state amp

[trussrod20`]

I have a 1972 Gibson 30 watt solid state guitar amp that makes a strange intermittent noise just setting there with nothing plugged in and all setting at zero. It sounds like one of those old gag type fart machines. I took it to a local tech but he could not find the problem. Can anyone help me? Thanks.

[loudthud]

Since you are new to the forum, what is your experience level, novice, hobbyist, pro tech? Can you identify and replace components?

If the amp makes the sound with all the controls down, the problem is probably in the power supply or power amp.

Can you post a copy or a link to the schematic?

[Jazz P Bass]

Schematic:

[loudthud]

Jazz, thanks for the link but I'm getting clear.gif 1x1 pixels ???

[g1]

Try this one:

[loudthud]

In my experience with this type amp, C14 is the main suspect. Since the amp is 40+ years old, it probably needs all the electrolytic caps replaced.