Very loud intermittent amp problem.

[nedhogan]

This problem will come and go but today its been very bad. It sounds a bit like when you touch the hot wire of a plugged in guitar lead or something. It is as loud as the guitar and i can't seem to diagnose the problem because its not there most of the time.
Could it be; a bad tube, a bad earth connection, a bad cap, a bad switch or relay, or something else?
It isn't the cable I've used different ones but it does seem to be affected by hitting the amp or switching it off and on again.

Advice on diagnosis or possible remedies WELCOME!

[Enzo]

It could be any of those, and more.

Isolate the problem.

Does it do this with NOTHING plugged into the amp? if it only hums when a cord is pl;ugged in, then perhaps the input jack needs to be resoldered or replaced. If it hums even with nothig plugged in, then the amp has the issue farther in.

Do ANY controls affect the noise in ANY way? Can you turn the hum up and down with the volume control? Or affect the tone of the hum?

Soes it still hum with ALL the control down to zero?


And whenever you need help with an amp, you REALLY need to let us know the make and model, so we know what we are dealing with.

get out some wooden chopsticks - they don't conduct electricity - and while the amp is running, poke every part on the circuit board. Does moving anything affect this?


Do you have FX loop jacks? Plug the guitar into the FX return jack and zero its volume control. Still hum?

[nedhogan]

Thanks enzo.
Its a fender super sonic 60
Not my amp of choice.
Its actually a friends amp but he knows squat about electronics.
The problem goes away again before I get a chance to
mess around with it. I will give it a poke and see how things go.