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I've had this Tubeworks RT-3100 bass combo for quite some time and until recently has been troublefree.
The amp powers on and works fine for about 15-20 minutes, then there's a background sizzling sound that gradually gets louder over time. It increases to the point of being unbearable.
This occurs with nothing plugged into the input and is not the result of interference from light dimmers, etc. It also manifests when I use an external cabinet instead of the internal speaker. I've also noticed that if I reach into the back of the combo and apply pressure to the sheetmetal, the pitch will change. I hypothesize that the power transformer has loose laminates that vibrate more as it warms up, but I don't know how to go beyond conjecture on that angle.
Because the problem manifests over time, I'm unsure how to go about diagnosing the problem. I've also had no luck finding schematics for this amp. Any suggestions would be greatly appreciated.
The amp powers on and works fine for about 15-20 minutes, then there's a background sizzling sound that gradually gets louder over time. It increases to the point of being unbearable.
This occurs with nothing plugged into the input and is not the result of interference from light dimmers, etc. It also manifests when I use an external cabinet instead of the internal speaker. I've also noticed that if I reach into the back of the combo and apply pressure to the sheetmetal, the pitch will change. I hypothesize that the power transformer has loose laminates that vibrate more as it warms up, but I don't know how to go beyond conjecture on that angle.
Because the problem manifests over time, I'm unsure how to go about diagnosing the problem. I've also had no luck finding schematics for this amp. Any suggestions would be greatly appreciated.
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