Electronics friends: I have a PoE hat for the Raspberry Pi that died in my cluster.

When connected to the switch, what I believe is the inductor (big package 330 on it) gets searingly hot.

I believe the inductor(?) burned out, but I am interested in why it could have failed.

@Rika The components around it don't get hot?

@x44203 Not as far as we are willing to keep it plugged in a failed state.

The temperature of the inductor skyrockets to being untouchable without burning yourself within seconds of plugging it in now.

On a working board, it is just reasonably warm all around.

@Rika Hmm, I'd expect the FETs to get hot if they failed... A schematic would be useful...

Can you measure the resistance across the inductor?

And do you know whether the PoE supply is isolated from ground? This PoE converter only has an inductor instead of a transformer, I think it assumes that the supply is isolated for that to work...

@x44203 @Rika I'm pretty sure there is an IC with integrated FET below that heatsink, and it probably got a short between source and drain

The strange thing is that the PoE source should turn off faulty devices like this one, and it is obviously not doing that.

@uint8_t @Rika That would explain why the inductor gets hot, even if it usually has low enough resistance to power a raspberry pi with 2 A without getting hot...

@x44203 @Rika the hat's model number is U6109 (from uctronics) but they don't publish schematics or what IC they use

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