I've been working on rebuilding / repairing a Fisher 660A console amp and have finally gotten to the point of firing it up to check voltages. While the B+ to the OPTs and the B+ to the 7591 plates appear to be close enough, the HV to the 12AX7 tubes (both known good) is significantly higher than it should be (381V instead of 320V). My thought is that I need to increase the value of the resistor just upstream (currently 2.2k) in the power supply, but I'm not sure as to how much to increase it. There is also a resistor just downstream, but it is effectively not in the circuit as there isn't a preamp connected to it. All components of the original power supply are in place (including those bits that aren't doing anything because of the lack of preamp).
Here's the overall circuit (somewhat hard to see):
Here's the close-up of the power supply:
Thanks in advance,
-D
Here's the overall circuit (somewhat hard to see):
Here's the close-up of the power supply:
Thanks in advance,
-D