So I have this 45wpc KT88 PP stereo power amp and lately there is hum in the right channel that sounds like 60hz. I swapped tubes and that didn't help, I checked all the power supply capacitors and they all seem fine. The builder used one power transformer for both channels but uses two 5AR4's (one for each channel) and looks to be wired as half wave rectifiers with the plates in parallel, from the power transformer one high voltage secondary goes to both plates on one 5AR4 and the other HV secondary goes to the other 5AR4's two plates, the center tap goes to ground.
The only thing that I can see that is strange is that the builder had placed .022uf caps in series from the heater center tap to ground. What is the purpose of these?
Thoughts on what to tackle first would be very helpful. Maybe I will replace the two .022uf caps on the heater supply or just remove them if they aren't that beneficial. Or for $60 I could just replace all the filter caps. All this will be cheaper than having it shipped to the builder.
The only thing that I can see that is strange is that the builder had placed .022uf caps in series from the heater center tap to ground. What is the purpose of these?
Thoughts on what to tackle first would be very helpful. Maybe I will replace the two .022uf caps on the heater supply or just remove them if they aren't that beneficial. Or for $60 I could just replace all the filter caps. All this will be cheaper than having it shipped to the builder.