Hi, 63Polara
Do you have the correct schematic for your amp? The ones I found for the J12b don't look quite right.
To me it sounds like your problem is in the oscillator circuit, and a resistor that has drifted way off from its value could cause this.
I would also check the speed pot for poor contact.
beinhard
Do you have the correct schematic for your amp? The ones I found for the J12b don't look quite right.
To me it sounds like your problem is in the oscillator circuit, and a resistor that has drifted way off from its value could cause this.
I would also check the speed pot for poor contact.
beinhard