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If your 115 volt line is still disconnected from the 115 B+ source, and you insert the 12au7 and get a 50 volt reading on the disconnected 115v bus line, that's because the 265 volts at the plate (pin 6) is being dropped through the plate resistors and cathode resistor. Then when you also insert the 6au6 it drops the same 265 volts through its
plate (pin 5) resistor and cathode (pin 7) resistor. Remember the current in those tubes starts to flow because you connected a voltmeter to an open circuit, the disconnected 115 volt B+ line. If you tested the 115 line after replacing the 6au6
first you'd get a different reading.
Did you recap the entire set. I would also make sure C36 in the 6ah6 (pin 1) is
not leaking. An easy test is to remove the 6ah6 and read the voltage on pin (1).
If you still get a positive voltage reading then C36 is defective, most likely.
Ed
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