did my poe switch fry my computer?

[electret]

New 10 port megabit switch with two rj45 uplink ports. Powered it on.
Connected switch uplink to laptop ethernet port. Tried to reboot (shut down and reboot) the laptop but it would not power up after the shut down.
My laptop refuses to boot up. No POST/bios screens etc. No smell or fumes observed.
Could the switch kill my laptop? or, could it be the ethernet cable which connected the switch and laptop's ethernet?
Before sending my laptop for a warranty claim, I need to understand what possibly happened.
I am sure i did not connect any poe port to laptop.
Is there a way to test a switch? I know tough call. But still.....
Could static charge cause my laptop to go flatline?

 

[CanCuba]

New 10 port megabit switch with two rj45 uplink ports. Powered it on.
Connected switch uplink to laptop ethernet port. Rebooted laptop and thats it.
My laptop refuses to boot up. No POST/bios screens etc. No smell or fumes observed.
Could the switch kill my laptop? or, could it be the ethernet cable which connected the switch and laptop's ethernet?
Before sending my laptop for warranty claim, I need to understand what possibly happened.
I am sure i did not connect any poe port to laptop.
Is there a way to test a switch? I know tough call. But still.....
Could static charge cause my laptop to go flatline?

POE switches are supposed to negotiate the voltage. If none is negotiated with the laptop, there shouldn't have been any POE voltage supplied by that port.

But I'm interested to hear what the pros have to say.

 

[wittaj]

Unless it is a really cheap switch that doesn't specifically say it meets 802.3af/at, then as mentioned above the switches auto-negotiate if power is needed.

Probably just coincidence.

 

[alastairstevenson]

The uplink port presumably is not a PoE port, so should not be a risk to the laptop.
And as you say, neither should a PoE port be a risk either assuming it's standards-based.

If you have a multimeter, it would be worth checking the switch power supply voltage, both sides, relative to the mains ground, and the switch metal casting or ground lug.
The power supply should be sufficiently isolated that you will not get a solid reading matching what the supply voltage is, probably 48v.
Then do the same for the laptop power supply.

An Ethernet port should be pretty well isolated from ground. The signals are isolated by the ethernet transformer, and there should just be some capacitors and a high value resistor to ground at the transformer centre taps. So normally no easy way for any large damaging current to flow from any device connected to the port, even if the connected device isolation is faulty.

I've seen a Hikvision NVR where the internal 48v power was tied to the external side of the ethernet transformers, such that any connected cameras and their wiring absolutely needed to be isolated from ground to avoid potential damage. The NVR fault was a shorted TVS (transient voltage surge) protection diode.

 

[Perimeter]

Connected switch uplink to laptop ethernet port. Rebooted laptop and thats it.

So you connected the switch, and the laptop merrily continued to work until YOU rebooted it?

 

[bp2008]

There's a million things that can go wrong with a laptop. We don't have enough information. As was pointed out we don't even know when or how the laptop shutdown occurred relative to plugging in the ethernet cable.

I think it is extremely unlikely that a network switch or network cable could kill a PC just by plugging into it. Kill the network port, sure, if something was horribly wrong, and you'd probably see, smell, and maybe even hear the magic smoke escaping.

At this point for all we know the battery is dead on the laptop, or the screen's backlight has a broken wire, or 999,998 other possibilities.

 

[electret]

There's a million things that can go wrong with a laptop. ...

The HP laptop was shut down within 10 minutes after the switch was connected to the ethernet port. The switch stayed connected to the laptop for less than a minute. The switch is unmanaged ethernet switch.
I did not see any fumes, smoke etc. No smell at all. It holds true for both the laptop and the switch.
The laptop battery is working fine. I tested it in a different laptop of the same make/model.
Yes the possibilities are endless unfortunately when it comes to the laptop. Unless the problem with the laptop is diagnosed, i am not ready to use the switch with a different computer because it maybe a defective or counterfeit unit.

 

[electret]

The uplink port presumably is not a PoE p.........

Thank you very much for taking your time to share knowledge and advice. I feel indebted.

 

[Perimeter]

The HP laptop was shut down within 10 minutes after the switch was connected to the ethernet port.

It is still not clear by whom. Did you tell it to shut down and it then shut down the way all good laptops do? Or did it take roughly 10 minutes and it went "pew" and was never heard of again? Or did you notice that after 10 minutes it had shut down for reasons unknown? In your initial post you called it a reboot, which in my understanding differs somewhat from a shutdown. I still have no idea how the problem came about.

 

[electret]

I have elaborated my original post. I had shut down the laptop to power it back on manually. However, it failed to power up right after that shutdown.
I bought the switch from an apparently reputable local seller. But theres no warranty. The box was open. The antistatic cover/bag was not factory sealed either. I did perform a physical inspection and the body of the switch seemed new. Taking a peek through the vents, i did not notice any dust at all.

 

[Perimeter]

Tried to reboot (shut down and reboot) the laptop

Why did you do that?

Is there a way to test a switch?

I bought the switch from an apparently reputable local seller.

Have the seller test it for you.