Intermittent hum problem - JCM900

Uk Ant

Uk Ant

New member
My little 50w JCM900 1x12 combo has developed an intermittent hum.
I suspect it's a loose joint on one of the smoothing caps.

Now I could just open it up, re-do the joints around that area and then see if it's better. Not over keen on this idea as it'd be just my luck if one of the caps hasn't discharged.
Anyway, any other opinions on why this could be happening?
 
Re: Intermittent hum problem - JCM900

If it's built anything like my JCM2000 on the inside, solder joints seem pretty likely. Be warned, though, that caps in tube amps are a dangerous place to poke around if you don't know exactly what's going on in there. As in "hundreds of volts and plenty of current" dangerous. But the simple fact that you used the phrase "smoothing caps" leads me to believe you already know that better than I do.
 
Re: Intermittent hum problem - JCM900

Yes Jessie, 400 volts worth of pain, which I once, in my youth, managed to discharge across me. It was an interesting experience, but not one I want to repeat :)
 
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