05-20-2012, 11:07 AM
Music, If you have a 60 cycle (probably 120 cycle) hum, there would have to be at least two tubes lighting, the rectifier (80) and the output (47). If most of the tubes don't light, my guess is, someone removed the good tubes and replaced them with duds. Though it is possible that there is a break in the heater circuit.
Steve
Steve
M R Radios C M Tubes