Power Surge!

[bongman_uk]

Hi all
Just found out something unusual, and thought it might be an idea to post here...
Last week, my nan called me asking for help with her PC. It seemed she just couldnt turn it on. As she only lives around the corner, I went round, and checked it out.
When I got there, I found both the PC, AND the NTL cable modem, with no power! Both were powered by a mains surge protector.
All her other devices and sockets seemed to work still. I checked all the plugs with a device that still worked. I concluded it must have been a power surge. For some reason it only affected the cable modem (NTL 120) and the PSU. I told her to call NTL to replace the modem and I would fix her PC.
When I got it home to diagnose it further. I Took out all the parts and tested them. Everything worked, except the motherboard! (although, I didnâ₠¬Ã¢â€žÂ¢t take the motherboard out of the case)
It wasnâ₠¬Ã¢â€žÂ¢t until today, when I had time to rebuild it and put in the replacement motherboard.
This is what I foundââ‚ƚ¬Ã‚¦..

She only has one PC, directly connected with Cat5, to the modem with an on-board NIC. Both devices were powered using a surge protector. The only way this could have happened is if a surge came down the NTL line, and blew her motherboard or, the Cable modem blew taking out the NIC on the Motherboard!

Anyone ever seen this happen before?
It was the last thing I expected!

[Toilet-Duck]

I had the exact same problem a few years ago on my "Tiny PC" the whole pc was fried they had to replace the motherboard, hard drive, psu and memory. Luckily though I was on the protection plan and they replaced all the parts.

[Chicken]

Originally Posted by bongman_uk

The only way this could have happened is if a surge came down the NTL line, and blew her motherboard or, the Cable modem blew taking out the NIC on the Motherboard!

..or alternatively, the motherboard failed and surged down the network line and took the cable modem with it.
When NTL replace the modem, see if they will leave the old one so you can perform surgery on that and see what's damaged in that.....

[nffc]

Originally Posted by Chicken

..or alternatively, the motherboard failed and surged down the network line and took the cable modem with it.
When NTL replace the modem, see if they will leave the old one so you can perform surgery on that and see what's damaged in that.....

If that's the case, the most likely cause is a failed/unstable PSU. What PC is it?

[Druchii]

Highly unusual. To me that says the fault came from within the SACM or the PC itself, as normally surge protectors do a decent enough job. Not seen that before though.

Saying this, you have power surges, i've just had a power cut!

[nffc]

Originally Posted by Druchii

Highly unusual. To me that says the fault came from within the SACM or the PC itself, as normally surge protectors do a decent enough job. Not seen that before though.

Saying this, you have power surges, i've just had a power cut!

I wondered what had stopped you...

[bongman_uk]

I built the PC myself

550Watt PSU
ASUS A7n8x Deluxe Motherboard
XP 2500+ Barton CPU
512MB RAM (Branded)
GF2 MX 440 Graphics


NTL have already replaced the modem with a new NTL 250, and taken the old one. I wouldnt expect them to let me keep the old one anyway.

[nffc]

What make's the PSU and do you have the amps? That motherboard is good so i doubt it's that.

[paulw37]

I have recently had experience of a power surge coming through the Cable connection. We had a thunder storm a few weeks ago and lightening stuck very close to my house. There was a loud bang from the corner where my television is but the only items affected were the set top box and my router. Both of these were completely fried, would not power up at all and needed to be replaced.
Both of these items were protected by surge protectors but the only connection between them is a Cat5 Ethernet cable. The two devices are actually in different rooms.

So yes in answer to the original post, I do believe that power surges can come direct from the cable connection.

[bongman_uk]

Originally Posted by nffc

What make's the PSU and do you have the amps? That motherboard is good so i doubt it's that.

Qtec

I know, not the best. The PC probably only needs 350, but its a 550
(I think its this one http://www.qtec.info/products/product.htm?artnr=13492)

And, the PSU still works on the new motherboard.

Not sure what the Amps rating is.

[nffc]

Originally Posted by bongman_uk

Qtec

I know, not the best. The PC probably only needs 350, but its a 550
(I think its this one http://www.qtec.info/products/product.htm?artnr=13492)

And, the PSU still works on the new motherboard.

Not sure what the Amps rating is.

As i had suspected - Qtec / Bestec both pretty ****e.

What has probably happened is they've used their random number generator to slap a 550 on the thing when it probably blows up after drawing 550 for a split second. The stable load is more important as i have said on here in the past - you need some leeway, even more for a Q-tec.

Probably the PSU has had a blonde moment and sent a surge through the MB - PSU will still work, but they just cannot be trusted. Just type Qtec rubbish or something similar into Google and have a look at the results.

[bongman_uk]

So then the PSU, fried the motherboard, AND the cable modem, but left the other more delicate parts (CPU & RAM) alone?

What makes me sceptical about blaming the PSU, is that the burn marks were by the on-board NIC, exactly where the Cable modem was connected. That suggests to me that too much power crossed that point. (there was also lots of soot marks inside the case, under that point)

If the PSU were to do that, the damage would be caused elsewhere.

It seems a large charge, came from the cable modem to the PC, frying the On-board NIC, then discharging through the case.

[Nilrem]

I would be suprised if it was a problem with the CM that killed the motherboard, I too would suspect a fault with the motherboard or PSU.

I've had PCI cards go pop on me (litterally) causing scorching of the motherboards PCI socket and stopping the PC from booting again until the card was removed.

In one case it was a capacitor on an NIC that went bang taking out a PCI socket but the rest of the machine was still fine afterwards (one of my neighbours has it now, 3-4 years after the card went pop).
If it had been an integrated part of the motherboard the motherboard would have been unusable, and it may have taken the PSU out with it.

[Badders]

Originally Posted by paulw37

I have recently had experience of a power surge coming through the Cable connection. We had a thunder storm a few weeks ago and lightening stuck very close to my house.

Extactly the same here. Luckily, the only thing which blew was the cable modem and the NIC in the computer. The NIC blowing must have stopped any damage to the motherboard as it's still working perfectly.

[sollp]

The power surges that are being talked about could come from anything that is connected to either the mains supplyor telco socket. I'm no expert on this but the power can enter at any point, you would have to have surge protectors fitted every where and still you can't really be sure you are safe.

So i find it hard to blame anyone particular electrical appliance that could possibly be the entry point for any suge caused by lightening. Remember these hit the ground and can cause damage even from a good distance away without hitting your house.

Like i have already said you would need to have surge protectors at every point and also between different devices and even this would not be totaly safe.

Also the cable coming into your house should go through an isolator before going into the modem or STB.