I actually found an older post from Nelson Pass explaining that the offset increase is normal when you have no load across the speaker outputs on shutdown. He said 1V is normal. I'm slightly over that, but I don't think it is a problem or a symptom
So I just compared all the measurements on the bad channel versus the good channel and I agree the problem seems to be Q6 and in particular the source lead, which shows dropping voltage. The other three mosfets seems to match the measurements on the good channel pretty closely.
Also, as Q6 drops in voltage, it appears to put more strain on Q5, which gets very hot pretty quickly.
I have replaced Q6 twice now, so I'm pretty sure that the mosfet itself is not the problem. Any one have a theory on what could cause this?
For anyone who reads this thread in the future and has a similar problem with the bias being unstable and/or uneven voltage on the CCR state source resistors, my problem ended up being the source resistors themselves.
Although they measured fine, when I replaced them, the broken channel worked immediately and is perfectly stable (I had already replaced all the mosfets and Q2, Q3, and Q4, so I know those were not the problem).
So the takeaway is, even if the source resistors measure fine in circuit, try replacing them.
Although they measured fine, when I replaced them, the broken channel worked immediately and is perfectly stable (I had already replaced all the mosfets and Q2, Q3, and Q4, so I know those were not the problem).
So the takeaway is, even if the source resistors measure fine in circuit, try replacing them.
Great to hear that you got it figured out! The Aleph J is a great amp. Now sit back and enjoy the music!