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Well I've been at it for awhile and I've improved it somewhat.
I'm sort of reaching the end of the line.
I might try increasing the 2nd filter cap to 100uf.
I've seen one or two other guys with a similar problem.
If anybody has any last ditch ideas?
But this amp has a bzzz and hum problem as I turn up the master and the gain seems to bring up the bzz.I think it's rectifier bzz. It goes away with v2 pulled.
The back end seems to be sort of ok.
I moved the big first filter cap off the board and the red hv wires away from the pcb.
The voltages on the heaters were too high so I brought them down with some diodes.
This helped some with the bzz.
I've attached some schematics so you can see where the bzz and hum are killed when I short to ground.Also picking up the radio when I go to ground from pin 7 on v2.
I'm sort of reaching the end of the line.
I might try increasing the 2nd filter cap to 100uf.
I've seen one or two other guys with a similar problem.
If anybody has any last ditch ideas?
But this amp has a bzzz and hum problem as I turn up the master and the gain seems to bring up the bzz.I think it's rectifier bzz. It goes away with v2 pulled.
The back end seems to be sort of ok.
I moved the big first filter cap off the board and the red hv wires away from the pcb.
The voltages on the heaters were too high so I brought them down with some diodes.
This helped some with the bzz.
I've attached some schematics so you can see where the bzz and hum are killed when I short to ground.Also picking up the radio when I go to ground from pin 7 on v2.
Attached Files