PC makes PSU Pop

Dr Zoidberg · 5 Sep 2007 at 00:14

I have been asked to look at a pc for someone that is causing new PSU's to blow.
I dont think a great deal has been done with it so far.

The first thing i was going to do is strip everything out so i am just left with motherboard sat on a anti-static bag, plug in the new PSU they have left me and see what happens.

If it hasnt gone bang after that i will slowly add parts back in, in the following order, turn it on to chaeck the PSU is ok between each part

CPU
Memory
Graphics card
HDD
CD Drive
Other things

if it is all still working at the end it can go back in the case and see what happens then.

Is there anything else i should /shouldnt do ? apart from make sure that if this PSU goes pop they know it is not my responsibility and they have to replace it.

Is there any part that is more likely to be causing this to happen ?

Is it most likely to be the motherboard ? in which case im not sure i want to try anything at all as its just going to pop the PSU as soon as i plug it in.

Thanks

Mattus · 5 Sep 2007 at 01:24

How many PSUs has it killed? Were they quality PSUs or rubbish brands?

mattyrigby00 · 5 Sep 2007 at 09:19

that way of testing should find it

also rest the motherboard just on a cardboard box or something, the static bags are conductive.

Dr Zoidberg · 5 Sep 2007 at 13:17

The PC stopped working, he got someone to have a look they tested the PSU and it was dead,
A new one was purchased and that went pop so looks like two dead.
The one i have been given is a V Cool 480w
I think this is a direct replacment for the new one that popped so guess that was the same model.
Guess that could hve been a dodgy PSU out of the box.
Hopefully going to get it stripped down and tested this evening. Will put it on a box rather than anti static bag.
At first look i would say a 480W PSu is more than enough for what is in the PC, its nothing special.

Dr Zoidberg · 5 Sep 2007 at 21:30

OK stripped it all out of the case and fired it up, slowly adding parts it was working ok,

Then the graphics card goes in and i connect monitor keyboard and mouse, cant get to the bios

Im getting errors such as diskette drive A errors and check sum errors every time i reboot it.
Have cleared the cmos several times and that changes what error i get.
After an error i press del to enter bios as it says but no response,

Once got into the bios but a few secs later it reset its self but failed to restart properly.

Im now banging my head against the wall.

Amonlym · 5 Sep 2007 at 21:41

check the capacitors on board for signs of leaking/bulging.

thats my first guess

Dr Zoidberg · 5 Sep 2007 at 21:53

Two of the taller ones near the CPU are bulging on the top, the rest are flat if not slightly concave on top, but these two are definatly bulging out.

Looks like the board needs replacing,

Another odd thing has popped up, may just be a dead hard drive but i have never known one to cause this before.
Connect it to the board and the system will not turn on,
One hard drive is ok and will start, the other will not start, and that is the same with just the power cable and no data cable connected.

Amonlym · 6 Sep 2007 at 09:20

good old caps :/

probably find that that hdd took the brunt of the old psu's death throws.
What make is it?
heres some examples of how various drives respond to bad voltages (ive killed a LOT in the past, and repaired some - i can provide pictures)

Maxtor DM+9: ST Micro "Smooth" chip on pcb burns up. very obvious. drive needs new pcb, data will be fine. - replacement pcb from another +9 of same spec will allow reads but writes tend to fail.

Samsung Spinpoint P PATA series: Small black component on pcb close to +12V pin - appears to be a fuse - will become non-conductive. drive operations restored by bridging this component.

Seagate 7200.9 (iirc) PATA: Another small black surface mount item dies, again close to +12V line. this one shorts +12V to ground causing failure for whole pc to power up. this component will slightly scorch the pcb arround it and smells distinctively of silicon heaven. - drive operation restored by removing component.

Disclamer: your milage may vary; do at your own risk.

(cheapo USB hdd adapters can be very expensive if you dont realise their hand in things :'()

*edit*

i forgot to say, if you are handy at soldering you can replace the capacitors with same or better specified units with a good chance of restoring the board to full working order....