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).
Stock configuration but with 12v transformer, so just over 15 volts. Sorry for mis-information.
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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...
I realized that I should have listened to see if both channels were acting up, but I was anxious to get it powered down. I'll check those things. Thanks!!!
If you suspect oscillation, you could try ZM's dohickythingamejig.
http://www.diyaudio.com/forums/pass...scillation-detector-question.html#post4347103
I think I've discovered the problem. I hope so. I'm just buttoning it up. I think I broke a wire going to the rectifiers, so it was missing either the plus or the minus voltage. I hope that is the problem. We'll see.
Cubie 2 is singing again... it's funny how bad it sounds with an inadvertent SE power supply!😀 Took some time to button things up a little better. What a great amp!!!
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... 😀
I didn't impregnate anyone in my early life, and I don't want to replace speakers in my later years. Better to use protection!😀
Does anyone have a tested gerber file or proper scale pdf file of the Cubie 2?
I'll give a shot at etching my own
Thanks
Do
I'll give a shot at etching my own
Thanks
Do
Send me your Email by pm and I can send you mine if you want, in return I just want to know how it compares to all your other amps 😀 You can see my version in post 72
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Very nice design. Parts ordered .Thanks Juma.
Jeffrey, Got the PDF files Thank you.
Regards
Joshvi
Jeffrey, Got the PDF files Thank you.
Regards
Joshvi
Is it detrimental to sub a 1 uF cap in place of the 470nF cap? I have the 1uF cap but would have to order the 470nF. I could series two 1uF if needed, or I could order the correct part. If I order, which one? The stacked ceramic are nice and small, but what is best for sound? Thank you!!!