Repairing a Dead Motherboad Due to Shorted Mosfet

Posted by crimsonpisang on   0 comments   0 trackback

I've picked up a dead mobo for under 5 bux. The board in question is an MSI 785GTM-E45 AM2+ mother board. After some quick diagnosis, I found that there was a short on the ATX12v rail. One of the VRM phase high-side FETs were toasted. Measured a short across the gate and source pins.

The each phase has the FETs in pair configuration, so 50% chance that both were toasted, 50% chance that only one was toasted and 50% chance of removing the good FET. I had the later one. The mosfet is an N-ch Niko Semi P0603BD. I don't have an exact replacement part in my junk bin but had something close to it.

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The board comes alive again and everything seems hunky-dory. That's another $2 quick fix and saving this fine board from the landfill. I was pretty lucky that it was a simple problem to fix and how a $1 part could killed a perfectly working motherboard.

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