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Positive power supply rail at a different potential than negative rail?
Positive power supply rail at a different potential than negative rail?
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Old 17th October 2019, 06:32 PM   #61
The Lord Flashheart is offline The Lord Flashheart  United Kingdom
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Then its probably fine.

Any idea where the strange voltages on Q101 and Q202 could be coming from?
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Old 17th October 2019, 06:40 PM   #62
Osvaldo de Banfield is online now Osvaldo de Banfield  Argentina
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The most common causes of such a kind of failures are resistors (Open or altered, usually in the increasing resistance direction), transistor or diodes. Also a severe leak from a electrolytic cap. but less common.

Check R210, R212, R214, D201 and Q202/3.
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Last edited by Osvaldo de Banfield; 17th October 2019 at 06:56 PM.
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Old 17th October 2019, 08:09 PM   #63
The Lord Flashheart is offline The Lord Flashheart  United Kingdom
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Quote:
Originally Posted by Osvaldo de Banfield View Post
The most common causes of such a kind of failures are resistors (Open or altered, usually in the increasing resistance direction), transistor or diodes. Also a severe leak from a electrolytic cap. but less common.

Check R210, R212, R214, D201 and Q202/3.
They all check out fine Osvalsdo, thank you for your continuing help on this by way.
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Old 18th October 2019, 12:18 PM   #64
Osvaldo de Banfield is online now Osvaldo de Banfield  Argentina
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Ok. Let's try again, shorting C209. This will cause the output stage to be quasi inoperative, and in class B, so big dosis of distortion will appear, but let us know if this action tend to normalize the DC operating points of the stage.
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Old 18th October 2019, 02:13 PM   #65
Osvaldo de Banfield is online now Osvaldo de Banfield  Argentina
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I forgot to remember, that all this test, be done with the limited current supply, to prevent future damages.

Keep us posted.
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Old 21st October 2019, 02:16 PM   #66
Osvaldo de Banfield is online now Osvaldo de Banfield  Argentina
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And? No news, good news?
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