6uitarRich wrote:
How do I test for the 290 volts on pin 1 and 7 of the rectifier tube. Do I check each of these pins for a DC voltage using a chasis ground? Or do I check between pins 1 and 7 for an AC voltage? (this measurement was 643 volts for me)
You are testing for AC
If you measure from pin 1 to pin 7 (i.e. one DMM probe on each pin) you will read ~580V AC.
If you measure pin 1 to ground or pin 7 to ground (i.e. one DMM probe on pin 1(or 7), the other probe on ground) you will read ~290V AC.
643V AC is close enough to 580V, assuming you were measuring from pin 1 to pin 7. The amp does not have a load so the voltages will be high until you connect the rest of the tubes/speakers.