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originally posted in the OTL by mistake:
Hi all
I have a Conrad Johnson PV11 w/ phono section. I believe it has all original caps-yelllow and white CJ branded and also SCR in PS. . One small problem has developed - the left channel of the phono pre is a bit noisier than the right. The gain of both is the same and the channels sound alike. Just some extra hissy noise on the left channel. This is only on phono. All line inputs are clean. I pulled the cover and without any ins or outs connected measured the noise with my dig multimeter on the L and R outputs. With the volume all the way up I get single digit mV (2-4mV) at output with any of the line ins selected. I'm measuring between + out and ground. Phono is L=90 mV and R=around 30mV. 30 is to be expected I assume due to the added circuitry and components om the phone section. Not really noticable at lower volumes but it is audible when volume is louder. Tried changing tubes,etc and noise still remains on L channel so I suspect other components. I've attached schematic.
Any thoughts as to the culprit. I'm suspecting a cathode bypass cap or resistor.
Thanks
Bob
Follow Ups:
My experience w/ CJ is similar to Story & Mick-
resistor or cold solder joint-
Happy Listening
Similar issue with my previous CJ Prem.3. In my case it was a cracked solder joint where the socket's legs connect to the circuit board. My tech ended up reflowing the solder at all connection points. Over time, I eventually had all 9 tube sockets replaced. May or may not be your issue, but worth a shot.
I would suspect resistor(s) first. I had a PV2 and those had metal films that I didn't like. But finding which one - try a short shot of cold spray after a thorough warmup and see if mv or noise changes.
For caps measure voltage across and out of each cap in the circuit.
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