modding electronics (repair)

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freonchill

Weaksauce
Joined
Aug 23, 2005
Messages
72
might be the wrong forum to put this in

but i was working on repairing my av receiver
it was sony unit that the amp IC burned out
so i replaced it
and the new ones were getting too hot to touch immediately (1-5 minutes)

so i figured i should make a heatsink for the ICs
and i did - but when i was testing the heatsink i accidentially touched one of the fins to a component and another component on the mainboard sparked and died.

now, there arent any burn marks in the area of the "flash of light"

QUESTION: is there anyone here is good at electronics / circuits?
or know of a place to point me toward to either learn how to diagnose / fix this
or a place / users group in atlanta where i could take it and learn / fix it w/out going to a shop and paying an arm and a leg...

e.g. i want to be involved in fixing it - just need a little help since i dont fully understand circuits.

thanks

PS - please move this to another forum is it would be more appropriate there.

thanks again
 
You may want to check www.RepairFAQ.com or ask in sci.electronics.repair or an audio newsgroup (DIYaudio.com has one) because Sonys can be kind of wierd, like some made 10-15 years ago that would blow out because the chip that was supposed to protect the power transistors would destroy those transistors. Also if you buy ICs, there are some counterfeits, and a friend of mine got some fake power transistors from Fox Int. A better source is MCM In One.

Adding a heatsink may be a good idea for the long term, but it shouldn't be needed for just testing, even if the IC runs hot. Also I would get an oscilloscope to see if anything is oscillating, which can burn up a chip quickly.
 
The speed that the new chip heated up would make me think that the original damage was not limited to the ic amp chip, so the new chip may have lived a short life anyway. That, with the addition of shorting out the heatsink, would make me look very closely at the power supply before proceeding to replace the amp ic again.

As far as links go, ePanorama ought to be in every techie's link list.
 
ICs often heat up really quickly if they're installed incorrectly (wrong orientation).
 
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