Motherboard overvoltge protection?

[carlhoward]

Is it common for netbook or laptop motherboards to have overvoltge protection built in?

My friend's son tried to help charge a netbook (Gateway LT3120u, 19v) with my POE power injector (48v). :-(
Now shows no signs of life.

Just wondering if there's any hope.
Thanks

[Cliff Matthews]

Small currents from PoE injectors somehow give doubt the laptop wasn't pooched prior (my sons are sometimes reckless). Also, the 19v never reaches the logic on the mobo. It must pass through battery/charge chips and DC/DC convertors before that. If the 48v did anything, it may have hurt a mosfet or some TVS diode.

[wraper]

Often there is a TVS diode in parallel with charging input. In case of overvoltage or incorrect polarity it usually gets fried first. In such cases often it may be a relatively easy fix. But's it's still a component level motherboard repair.

[xavier60]

On the adapter input there is usually one or two MOSFETs for reverse polarity and under/over voltage protection. One might have a spiked Gate.