lightning damage

[astro]

Hi, my friend's PC was hit by lightning, probably through the AC side, since it will not even come on at all. He want's me to take a look at it for him.

My idea is, it is probably a total loss because of the surge. Anyone ever saved anything from a lightning hit?

[daveleau]

I have seen systems totally fried and some that only have one component fried. I would try a new PS and see if the rest is dead. It may not be a total loss. don't get your hopes up though.

Dave

[astro]

Thanks guys, I was thinking along the same lines. You idea's are appreciated.

[Graham]

Funny stuff lightning, can destroy sme bits, skip others, then go on the rampage again.

Had a strike once, killed the cd and soundcard, but left the rest alone.

Your only course is to fault it a bit at a time, obviously PSU first.

G

[Buji]

Open the PS and look to see if it has a fuse.

[daveleau]

Be careful opening your PS though because it carries a whallop if you touch it in the wrong place (even when unplugged).

Dave

[Thud]

Dave--I've never heard that before. How can a PS zap you if it's not plugged in? Does it somehow store a charge? Just curious.

[flea]

If it has a capacitor inside, they store charge, and you might accedentally discharge it, into you.

[NDC]

My buddy's system got his mainboard and 1 stick of 128mb fried. Luckily, the rest of his components weren't damaged.

[Mogui04]

I I I I I've bbeen ssssssstruck bbby lightning si-si-si-si-si-six-six-t-six-sixty-sixty-sixtysix times.....
Ininininininniin dah HEAD!!!!

[dragonB]

Yes, that power supply capacitor can pack a wallop. http://www.sysopt.com/forum/smile.gif Kind of fun though if you have a really weird mind.

[Bovon]

When lightning comes in thru the power lines, into a computer psu...what usually happens is it blows out the switching transistors, by way of the AC to DC rectifier system, then the charged capacitors discharge thru the shorted switching transistors, blowing out the psu voltage reglators. This in turn, allows a much higher voltage than the 5 and 12 volts needed to run the system, blowing out the mobo, cpu and sometimes, the drives. Lastly, the fuse blows!!

We do get lucky sometimes, tho...so, the first thing I would check out and replace, would be the psu. If, by chance the switching transistors opened up, instead of shorting...the damage will stop there.

Now, to relate how well a big capacitor can hold a charge, the following happened to me, a lotsa years ago.

I was building a (very) high powered radio transmitter. The voltage required was 4000 volts DC. I found a 200 MFD capacitor, rated at 6000 volts, so I proceded to 'bread-board' the power supply together, out on the work bench. Once, I had it up and humming (literally) I turned it off...I had measured the voltage at 4200 volts (no load). Later on, I was going to take it apart, and reassemble in my case...when it dawned on me, that I did not have any bleeder resistors attached, and that huge capacitor could still be holding a charge.

I got the largest, industrial strength screwdriver from the tool shed (about two feet long, and the shank was 3/4 inch thick..truly a big mechanics screwdriver).

I proceeded to short the two terminals on the capacitor, to discharge it. The flash and bang, sounded like lightning and thunder. I held in my hands, a screwdriver, that had been shortened by about 3 inches!!

Be carefull around electronics that may have charged up capactors...the voltage may only be a few volts, but will almost always make you wet your pants... http://www.sysopt.com/forum/biggrin.gif

[astro]

Thanks again for all your help. Maybe I will be lucky. That same lightning bolt got 2 TV's and 2 Phones also.

[Graham]

I'm with Dave and Bovon, ('bin there, dun that, got the scars to prove it), those psu caps hold a charge for a long time, and at a voltage higher than your supply (about 330V here in UK)

G