Power Supply Suspect?

[Catin Dehat]

I have a computer that has a dead ATX motherboard, apparently caused by an
overvoltage from a nearby lightning strike. The MB was declared dead by
using a known good power supply. It is not obvious that the original power
supply was ALSO damaged by the voltage spike, because a good UPS was
providing power to the computer at the time of the lightning. Would it be
foolish to connect the suspect power supply to the replacement MB?

 

[kony]

I have a computer that has a dead ATX motherboard, apparently caused by an
overvoltage from a nearby lightning strike. The MB was declared dead by
using a known good power supply. It is not obvious that the original power
supply was ALSO damaged by the voltage spike, because a good UPS was
providing power to the computer at the time of the lightning. Would it be
foolish to connect the suspect power supply to the replacement MB?

UPS does not protect the power supply in many cases, we
hadn't established the surge came in on the power line
through the PSU?

The best course here is to connect the power supply to an
old hard drive (or whatever, a small load on the 5V & 12V
rails), jumper the PS-On signal (pin 14) to ground (Com on
picture) to get it to start and measure the voltages on all
rails. If it appears to still work it would probably do
fine.
http://69.36.189.159/usr_1034/atx_on.gif

 

[kony]

If your old board was fried when connected to the power supply, your
best bet would be to ditch it. Considering the cost of a new board, its
not worth taking the risk. In any case, if a power surge was the cause
of the damage (are you sure of this) the power supply should have blown
its internal fuse.

You are assuming power surge came in through the AC power
line. Sometimes it seems there's magic smoke inside a PSU,
but really it's a bit simplier to test one, if it's turning
on still and outputting correct voltages, it should be
reasonable to try it. The inherant risk isn't so much from
there being a surge, it would be whether the PSU was decent
at all, before the surge event.

Sounds like the board has just died to me...
When you consider the total cost of every component in your case, you
come to realise that using a poor psu is a bad idea.

An argument to buy a new PSU to not risk the cost of another
component? You might be assuming the replacement
motherboard costs substantially more than the power supply?
Old boards can often be had for under $50, about the same
price as a PSU.

 

[Davy]

The first thing it normally gets at is the modem - try it with i
out..?

It has been known in these pages and first hand experience that al
was needed was a modem, more so if using dial-up

Thought I would just mention it

Dav

 

[don]

A UPS Conditions the power supplied to he computer and will supply pretty
good protection, but there can be alot of zap from lightning and arcs can
bypass alot of the protection.

If what you are saying is that you are not sure if the MB was damaged, then
you will not likely damge the PS in trying.