Jim, I've no helpful suggestions, but had that identical problem with my Phase Linear 4000 Preamp's right channel off and on for over forty years. I took it to three different repairman over that time, and even back to the Phase Linear factory, which was located outside Seattle back in the eighties, not too far from home then. None of them could find or engineer a permanent solution to whatever the problem was.
A bunch of replacement caps helped it keep going for a while the last time around. The final solution came last year in the form of a dumpster. I gave away the matching Phase 400 amp, which was still going strong and never a moments trouble. I wish you the best of luck finding a better solution in a much shorter amount of time.
Mike
A bunch of replacement caps helped it keep going for a while the last time around. The final solution came last year in the form of a dumpster. I gave away the matching Phase 400 amp, which was still going strong and never a moments trouble. I wish you the best of luck finding a better solution in a much shorter amount of time.
Mike