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Check the 12CU5 grid for 110 V. Quickly remove the tube and measure again. It should stay there. If not, check the resistors in the grid circuit voltage divider.
Does varying the volume control affect grid voltage, with the tube out? If so, replace the coupling cap.
Could be more than one problem; three I doubt.
Quickly remove and replace the tubes on the 130 V circuit, one at a time, while measuring the 130V supply. There could be a shorted tube loading the circuit.
Last edited by Don Lindsly; 02-07-2015 at 01:42 PM.
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