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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
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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.

Situation:
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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