sidespar

But if one of the power fets blew, wouldn't there be noticeable damage and smell? I blew a power fet in an audio amp before, which caused a loud pop, a horrendous smell, and a lot of smoke and physical damage. Plus it would still turn on afterwards, just wouldn't work. My board looks clean though.

Anyway, if a power fet is blown, that means there will be a short circuit between the drain and source (or gate and source), correct?

Togglehead

oh duh. missed that.

HIS4

They can blow without any noticeable smell and since it's sandwiched between those heatsink rails I suppose it could show some physical damage under there but I'm not totally sure. As I said, I'm not a small signal guy so this is a little out of my element. Looking at the article I linked, I'm having a hard time telling how the device would react to overcurrent and/or overvoltage conditions. The article does say that in the case where the gate/source voltage is significantly greater than the threshold voltage for the parasitic BJT, the BJT would be forced into a foward bias condition and could cause a catastrophic failure of the deivce.