fisher 400 tweaking issues

[grahamrunsran]

Hello all, I've a situation with a fisher 400. I've measured the voltage at pin 2 and ground on the power tubes after installing a new rectifier and caps and I get a nice -19.8, and my voltages across the 10 ohm resistors that I added to the power tubes for protection puts voltages where they should be (260 ma), but my 12ax7 filament voltage from the rectifier is 27.2. a few volts too high, how can i get it down and am I measuring the my voltages correctly by putting one meter lead on pin 2 of the power tubes and the other on ground? (for the preamp filaments I put one lead on ground and the other on the first filament.)

Should I lower R34 but raise R35 or something? I'm stuck.

[SY]

I don't have a schematic of that amp at hand, but what I'd do is measure the heater voltages directly across the tubes' heater pins. Some overvoltage is not uncommon because of the higher line voltages these days. That is not good for your tubes; the best way to reduce it is to use a 12V transformer as a buck on the primary of the old power transformer.

my voltages across the 10 ohm resistors that I added to the power tubes for protection puts voltages where they should be (260 ma)

I'm not sure what that means.