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Old 6th April 2012, 01:01 AM   #31
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Those both seem a bit high. Compare them to the other channel's corresponding components.
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Old 6th April 2012, 01:04 AM   #32
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Q220 and Q221 1.04Vdc
Q222 and Q223 1.15Vdc
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Old 6th April 2012, 01:05 AM   #33
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Should Q109 and Q111 be back in the circuit?
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Old 6th April 2012, 01:21 AM   #34
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I think both of the diodes in the other channel are defective. You shouldn't have much more than 2x 0.5v.

If you replace the diodes and the bias begins to work (turn fully CCW before applying power), reinstall those two transistors to see if the amp will produce audio.
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Old 6th April 2012, 01:22 AM   #35
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With Q109 and Q111 back in circuit I read .998Vdc and 1.2Vdc
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Old 6th April 2012, 01:23 AM   #36
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D106 is defective or D107?
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Old 6th April 2012, 01:29 AM   #37
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They both look defective. The diodes are simply two normal diodes in series. I wouldn't expect 1.7v across them. 2.4v is definitely too much.
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Old 6th April 2012, 01:41 AM   #38
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I replaced D206 and D207 and D106 and D107 and I have the lower half of the waveform now. It isn't a nice sine wave, the lower half is more triangle.
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Old 6th April 2012, 01:42 AM   #39
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Click the image to open in full size.

sent from a IRFZ48N
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Old 6th April 2012, 01:59 AM   #40
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With it loaded the bottom half of the signal is gone.
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