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Old 17th November 2012, 01:54 PM   #531
Rush is offline Rush  United States
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Originally Posted by anilva View Post
Continuing on my post where the left channel is showing very low gain compared to right channel. There is proper reproduction from the right channel and the left channel, while the sound is clean is barely audible at full preamp output.

What else to look for?

Thanks
Have you checked the values of the feedback resistors on both channels?
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Old 17th November 2012, 01:59 PM   #532
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Seems you have it under control then.
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Old 18th November 2012, 12:15 AM   #533
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Buzz...

Finished yet...............
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Old 18th November 2012, 01:10 AM   #534
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Nope, but thanks for the bump. I am doing battle with a cold. Did get thr other sink cut and the other heat spreader mounted. Just got to pull apart. Spread the heat goo and begin mounting components and boards. Also putting finishing touches on article spev'd psu. Trudging along.
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Old 18th November 2012, 01:26 AM   #535
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Seems you have it under control then.
Buzzb, if this is addressed to me, then I am far away from having any control on the situation. Just one change of jFETS has altered the entire voltage rating across the PCB. I have removed the PCB and checked the P1 and P2. They are set to zero ohms. I do not see any dry solder. I resoldered all of them. Checked component values - no errors. I need to check tracks of the PCB, if there is any flakiness associated with the board. I will report back.

Last option is to discard the PCB and build another board.

Regards
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Old 18th November 2012, 01:41 AM   #536
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Pics of the boards. Home brew or bought. Use mm to check traces, between traces, for copper hairs. Having one good channel, you have ultimaye guide. Start at input and work to output. Sounds like something is robbing current from one side of bias scheme.
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Old 18th November 2012, 02:13 AM   #537
anilva is offline anilva  India
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Pics of the boards. Home brew or bought. Use mm to check traces, between traces, for copper hairs. Having one good channel, you have ultimaye guide. Start at input and work to output. Sounds like something is robbing current from one side of bias scheme.
Thanks. Will compare every line. The PCB is from a India forum group buy. It has been designed by fellow member Om Mishra. While the PCBs look well made, I am probably the first guy to use these boards. There could be manufacturing issues or may be not. With time at premium, this debugging hogs quite a bit of that.
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Old 18th November 2012, 02:25 AM   #538
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Some people do crossword puzzles, others debug circuits.

Consider it time well spent.

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Old 18th November 2012, 03:25 AM   #539
anilva is offline anilva  India
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Some people do crossword puzzles, others debug circuits.

Consider it time well spent.

Papa, pardon me for using the wrong word 'debugging'. Who am I to debug a perfect design. I am just trying to find out assembly errors committed by mortals like me. While I prefer playing around with circuits than crossword, the anxiety to listen to a F5T in a hurry is driving me nuts.

Thanks.
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Old 18th November 2012, 05:34 AM   #540
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have you checked the output fets? you have about half the rail voltage as DC offsett with no voltage over any source resistors?
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