Computer wont turn on after loud bang + smoke

Hey Yall

Recently got a computer (Desktop) with some pretty good specs. Computer was on for about half an hour before a loud pop/bang was heard followed by the computer powering off completely. A smell followed by a bit of smoke then. Tried powering on computer since but no luck. I think it could be the PSU. When the power switch at the back is flicked on a green light shows up on the motherboard inside though which would say to me that it might not be the PSU? Any ideas what could be wrong? computer has been since plugged out and left alone.

moc moc a moc

Sounds like a blown capacitor, which certainly could be the PSU, but also could be on the motherboard itself.

maki

Could you give us the specs of the PSU and motherboard?

Have a look at the motherboard under some good light and look for any signs of damage. A blown cap will usually be pretty obvious.

If the PSU died (which is the most likely explanation considering the age of the machine) and the motherboard is ok, it's still possible that you'll still get some power flowing through to the motherboard to power that LED.
If the motherboard died and the PSU is ok, the LED might still light anyway.
Or the PSU died and took the motherboard with it (and maybe other components).

Simplest way to narrow it down is to grab another PSU from somewhere and see if it boots up with that.

Hey Yall

moc moc a moc wrote: »

Sounds like a blown capacitor, which certainly could be the PSU, but also could be on the motherboard itself.

checked the motherboard capacitors and they all look to be perfect from what I can see .. no deformities whatsoever so my bets on a PSU capacitor

riclad

OPEN the case ,
if its the motherboard, bad capacitor,
you,ll likely be able to see a small dark patch where the component is blown,
destroyed on the circuit board,
1 chip,or capacitor will be black,or dark .

https://www.ifixit.com/Wiki/Computer_Triage_for_Refurbishers
see good bad capitor image on the page/

remove the power cable from the esb socket, first,
power still goes thru pc ,even when pc is Switched off.

IT might be just a bad pc power supply.
ITS easy to get a repacement psu,
get one the same size, wattage, with the same end motherboard connector.
Theres 2 or 3 pc power to motherboard connectors,
depending on how old the pc is.

http://www.instructables.com/id/How-to-power-up-an-ATX-Power-Supply-without-a-PC/

You can test the power unit ,
by plugging it out from the motherboard,
see link above.
be careful.


i plugged an old phone charger into a esb siocket,a few weeks ago,to test it.
there was a loud bang,
it blew the fuse on my fuse board.
i reset the fuse ,by pushing it down.

First take out the power cable from the pc case.
switch off all power to the pc.

if theres a black mark on the motherboard,
the motherboard is likely to be dead ,faulty.
look at the fuse in the pc plug, is it black?
change the fuse,anyway.

Hey Yall

maki wrote: »

Could you give us the specs of the PSU and motherboard?

Have a look at the motherboard under some good light and look for any signs of damage. A blown cap will usually be pretty obvious.

If the PSU died (which is the most likely explanation considering the age of the machine) and the motherboard is ok, it's still possible that you'll still get some power flowing through to the motherboard to power that LED.
If the motherboard died and the PSU is ok, the LED might still light anyway.
Or the PSU died and took the motherboard with it (and maybe other components).

Simplest way to narrow it down is to grab another PSU from somewhere and see if it boots up with that.

Yup will have to send it to someone to do that for me. Dont know full specs as I didnt build it myself unfortunately but everything is relatively new .. the only thing im not sure about is how old the PSU is. Could anyone let me know as to the likely hood of other components being damaged? Literally just got it today so quite bummed.

leeroybrown

An ATX PSU always provides a 5V standby line to the motherboard once it's receiving A/C power. The 12V and 3.3V supplies will come through different circuitry after the initial power drop inside the PSU. A capacitor on one of those two paths is likely blown. If there was a loud bang it was almost certainly the PSU as it's unlikely any capacitor beyond the wiring loom of the PSU would be drawing enough current to blow like that.

Hey Yall

All the mother board capacitors are in good order .. Thoroughly checked with a flashlight unless theres some one hidden behind somewhere I cant see but I think i checked everyone .. Dont want to go rooting out the PSU as im not very experienced in dismantling computers.

leeroybrown

Replacing a PSU is actually pretty easy, the cables are all standard form factor and clip on/off easily *but* whatever you do don't open the PSU itself. Those capacitors can remain charged for ages especially if something has failed in the PSU.

fearrchair

Theres also two little components that used to be at the base of those large capacitors maybe its different now. l used to know them as movistors often it was just those and a fuse. l think they used to be wrapped in heatshrink and some silicon to steady then against internal vibration.

Your could be lucky and your PC is ok and its just a PSU.

riclad

TO remove the psu from the case, remove 4 or 5, screws ,as in link below,
One in each corner,which secures it to the pc case.
detach the psu, plastic connector from the motherboard power slot.
if psu is dead, its possible the motherboard is ok.undamaged.
DO not open the psu itself. http://www.hardwaresecrets.com/article/How-To-Replace-Your-Power-Supply/362

Maybe bring psu to a shop,and get one of the same size, wattage,eg 400 watt power.
with the case screw holes in the same place ,as the old one.