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Re: Continued with variac ......still have problems....

Larry -

Check voltages - especially on the bias circuit. I'd bet either the selenium rectifier or the quad 75uf cap has failed. The LK72 draws filament voltage for V1/2/3 off of the bias circuit.

If the quad cap is bad, you'll need to rebuild it. I'm not aware of any current replacement - it's a "can positive" cap, somewhat unique.

Don't fret about having the schematic for the 6GH8 version. The 7199 circuit will be essentially identical except for the pinout. It's just the phase inverter, and shouldn't be involved in your problem.

Just curious, which face plate does your LK72 have (brown or gold)?

- Gary



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