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Old 10th April 2012, 11:47 PM   #1
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Default Shorted output transistor

Shorted channel, just changed 2n3055 and mj2955 and driver transistor but now I have 27v dc on speaker terminals...
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Old 10th April 2012, 11:56 PM   #2
tvrgeek is offline tvrgeek  United States
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Totally out of context, but I would suspect a lot more than the output failed. A schematic or at least what you are working would help.
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Old 10th April 2012, 11:57 PM   #3
Join Date: Jan 2005
The failure may have propagated further back into the frontend circuitry and taken out VAS and possibly burnt some resistors.
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Old 11th April 2012, 12:16 AM   #4
Enzo is offline Enzo  United States
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One thing to ALWAYS check when transistors burn out is the resistors associated with them. An open resistor can put DC on your output just as surely as a shorted transistor can.
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Old 12th April 2012, 06:26 PM   #5
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Default It still distorts.

Thank you all.
There was another shorted transistor, I've replaced it and now dc offset is ok. But the channel still distorts sounds.

found the amp with Q611 burnt and R651 missing (?)
Q613, Q615, Q617 shorted
Q609 seems to be fine

Replaced all shorted transistors, inserted a new 180r resistor (R651).
What else?
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