Dead amp..nothing burnt, but visible orange crust.

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marcello7x

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Joined 2006
My amp died about 3 months ago and i finally got around to taking it apart to look at the board. I am not very experienced with working on board, but am studiing electrical engineering in school and know a little about this stuff.

None of the caps seem to be bulging, and all the transistors look in good shape, haven't tested them yet. Could the crust be because of early faliure from the caps? And the system when before they could buldge.


Also what is the best way to test the mosfets without removing them from the board.

Attached is a pic of the amp. its an audiobahn a2300hct.
 

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TO-3

TO-3

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Joined 2004
marcello7x said:
Which pins should i check? I did a quick test not sure what i was looking for and found some mosfets having a resistance of 0. Are those the shorted ones? A whole row of 4 on each side had this. I would have to replace all four on each side correct?
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A 0 ohm resistance would indicate that one ore all four of the devices has shorted. You must replace them all as if one goes, the other try to pick up the rest but it only stresses out the other remaining parts. You may be able to just swap the parts and be done with it or there may be another problem that caused the parts to fail. I did not look at the pic but I am assuming that they are power supply mosfets. Either they had inadequate heat-sinking or there may be a problem in the audio section.
 
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