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About Mosfet

Hi Audiogonians, Merry Christmas.

I got some questions about MOSFET.

First I would like to know how can one damages a MOSFET? Can wrong connection from powersupply kill it? Next up is how does a damaged MOSFET sounds like and how can one knows which one is dead if there are more than one in a poweramp? Finally, if there such a thing as life span of a MOSFET?

Equipment-Adcom GFA5500. Problem-One channel sounds like a weak reception radio. Cause-could be wrong connection. Can someone help me to trobleshoot this?
rainchild
rainchild OP
31 posts
 
Thanks guys,

Oohlala, Bombaywalla knows so much, how I wish I could be like you. I'd checked and yes, I got a 8A blown fuse. I'll replace it tomorrow and see how it goes. Thanks Unsound. Like an AM radio with bad reception. Is that what you've experienced?
bombaywalla's avatar
bombaywalla
1,958 posts
 
Unsound,

Incredible indeed!
I didn't think that a blown fuse would allow any power to that channel. Must be the way that the fuse was routed into the circuit. Many times amps have fuses but they are not in the direct signal path to avoid spoiling the sonics. In such cases the fuses do their job but not like a traditional fuse which might be in series with the circuit path & once blown would create an open circuit.

Ok, Rainchild, check them fuses!
marakanetz's avatar
marakanetz
5,473 posts
 
Most-likely you have one or more of the output device(s) failure.
rainchild OP
31 posts
 
Hey guys,

Bad news, I changed the dead fuse, amp was ok for a few mins and spark starts coming out and now the Mosfet of that faulty channel ready blown. Sent the damaged channel PCB to a nearby technician. Ask me some questions. He thinks it is because I didn't screw back all the screws that fasten the mosfets onto the heatsink. That's the price of laziness.
marakanetz's avatar
marakanetz
5,473 posts
 
Hey,
Nothing to wonder.
One channel was already going out due to the late action of fuse anyway. Hence the distortion on one channel you were experiencing.
Just next time make sure you fasten tight to the heatsink no-matter bipolar or FET so the tech won't have to make-up the reason.
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