Stock FW means +/- 23V. If so, it might mean overheating Q6,Q7 - check them if the are OK.
If those BJTs are still good, search for a bad joint or connection (mechanically, electrically, thermally).
That's OK. Obviously something went wrong - check current through JFETs by measuring voltage drop on R10/R12.
Then check the current through second branch by measuring voltage drop over R11/R13.
Also check the voltage between the gates of the output MOSFETs, should be about 3-3.5V. Then check the Id through them the same way you did when adjusting the bias.
All BJTs should have about 0.7V Vbe.
Compare all measured data between good and the bad channel.
If both channels developed this distortion than the problem lies in that what they have in common - the PSU. Once more, check all wires, connections, joints, isolation between MOSFETs and heatsink...
Then check the current through second branch by measuring voltage drop over R11/R13.
Also check the voltage between the gates of the output MOSFETs, should be about 3-3.5V. Then check the Id through them the same way you did when adjusting the bias.
All BJTs should have about 0.7V Vbe.
Compare all measured data between good and the bad channel.
If both channels developed this distortion than the problem lies in that what they have in common - the PSU. Once more, check all wires, connections, joints, isolation between MOSFETs and heatsink...
If you suspect oscillation, you could try ZM's dohickythingamejig.
http://www.diyaudio.com/forums/pass...scillation-detector-question.html#post4347103
Just out of curiosity, what would you image would burn out? I fried a couple of rectifier diodes during "refit", but that was a separate stupid human trick. Power supply was not hooked to amp when the spark/snick sound alerted me to the fact that it was still powered up. I really dislike that sound!
No, that's a sign of weakness - not having a trust in one's own build.
OTOH, nothing is foolproof - cable conection might develop a shortcircuit, faulty source component might produce significant DC at its output... When you start to doubt, you'd better use protection, even at a price of somewhat less enjoyable user experience...
OTOH, nothing is foolproof - cable conection might develop a shortcircuit, faulty source component might produce significant DC at its output... When you start to doubt, you'd better use protection, even at a price of somewhat less enjoyable user experience...
Mine are as in post #24. I can send you a PDF if you like. PM me if you want.
