Even after replacing filter caps, I had hum even with the volume turned down. I swapped tubes. No change. I checked voltages on the zener diode string and each was reading 36 volts instead of 33 volts. The regulator transistors Q2 & Q3 were bad. I used a MJE15032G for Q2 and MPSA42G for Q3. I replaced Q1 also with MPSA93G though it checked ok. Quiet as a mouse now! Ground rings on many jacks are bad. Next job is replacing them with jacks with nuts on inside of jack panel.
What might cause LOUD hum in a Conrad Johnson pv6
The PV6 today blared out a loud hum after it had been running fine for a couple of hours. I shut off all power to the amp, pre-amp, tuner etc. I noticed when I moved the preamp that one of the output cables was disconnected.
I don't know if it somehow disconnected and it caused a hum or became disconnected when I moved the pre-amp. In anycase, I later plugged the cables back in securely and used only a tuner STILL A HUM then a turntable and STILL A HUM.
I am looking for someone who might have an idea what is causing the hum. I opened the preamp No smell all tubes appear to be working. So I am puzzled.
randall
I don't know if it somehow disconnected and it caused a hum or became disconnected when I moved the pre-amp. In anycase, I later plugged the cables back in securely and used only a tuner STILL A HUM then a turntable and STILL A HUM.
I am looking for someone who might have an idea what is causing the hum. I opened the preamp No smell all tubes appear to be working. So I am puzzled.
randall