Member Avatar for martay75

hi, i recently moved my pc from one room 2 another and when turning on everything began to run as normal for about 5-10 secs bios page ect.. until smoke came from inside and then nothing all went dead, i disconnected lead @ plug then psu. the fuse has blown in the plug, i checked all components visually and cannot see any scorching or disforming. i removed cpu which looked ok aswell as did the mobo?. when i replaced the fuse and tried it again the fuse just blew instantly. i assume the psu has gone and will not try it again, but would trying a new psu with the existing mobo and components harm them if not already?.

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  • Latest Post Latest Post by Bob_180_Bob

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Short version for : because you saw smoke and a mains fuse blew, do not keep powering the machine. A replacement PSU can be ruined (and in rare cases other parts put at risk) if the motherboard has a hard short. Since you already tried a new PSU and it simply will not start, the next step is to confirm whether the motherboard itself has a fault before reattaching more hardware.

Build on what , and said, but focus the troubleshooting where it now matters:

  • With mains unplugged, remove the board and inspect closely around the CPU power area, the main ATX connector, the VRM/heatsink area and all capacitors. Look for darkened PCB, melted plastic, bulging or leaking caps, or tiny scorch marks — some damage is local and easy to miss at first glance.
  • If you have a DMM and feel comfortable using it, check continuity from the board’s main power pins to chassis ground. A very low resistance (almost short) on a rail indicates a board short. Note that capacitors can make readings look low, so interpret results carefully.

Safe ways to proceed:

  • Do not immediately connect another PSU to the suspect board. First verify the PSU independently (use a known-good system or a dedicated PSU tester) rather than testing it on the damaged board. Modern PSUs have protections and will often trip, but a persistent short can still kill a PSU.
  • If you find visible damage or an obvious short, get a repair shop to bench-test the components. After a smoking event the fastest practical resolution is often a motherboard replacement.

Final note: stop powering the unit until a bench test is done. If you are not confident with multimeter checks or mains-side work, hand it to a technician — mains-fuse blow + smoke is not a safe DIY escalation.

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Member Avatar for techsheaven

Keep looking, a fuse would not make a puff of smoke normally. Was the smoke from the mobo or psu? Did the fans all turn?

If you don't see anything wrong with the mobo or do find something burned in psu, I would replace it.

Edited by techsheaven because: typeo
Member Avatar for Bob_180_Bob

Hi,
Try unplugging every wire coming out of the PSU, replace the fuse and plug it in again. I suspect that there is a direct short inside and it will just blow again. As it is unplugged from any other component it can not harm anything else. If it does not blow the fuse and the fan inside is working then have a look at this youtube video:-
http://www.youtube.com/watch?v=VXzrCr0RLm4
If everything is OK then I would be looking at the mainboard.

Edit:- Checking the PSU this way will not mean that every part of the PSU is OK, it could have other faults.

Edited by Bob_180_Bob because: n/a
Member Avatar for mjdodd

agrfeed with above, but if all seems OK when everything is disconnected from the Mobo then reconnect one by one and see which if any of the mobo leads causes the psu to blow fuse. A jammed fan, or jammed drive will overload the psu...
M

Member Avatar for techsheaven

Depending on the type, the PSU may not start without the MOBO or connecting some pins.

Member Avatar for mjdodd

agreed but as long as ther is the on/off button connectors connected from switch to mobo (green & white wires norlmally) then it should go!
It may also as you sayneed one other connection fromù PSU to give a resistance etc
M

M

Member Avatar for Bob_180_Bob

Depending on the type, the PSU may not start without the MOBO or connecting some pins.

Watch the youtube video I asked the OP to watch.....
http://www.youtube.com/watch?v=VXzrCr0RLm4
it complies with the site you gave, it puts a load on the PSU allowing it to start.

Member Avatar for martay75

Watch the youtube video I asked the OP to watch.....
http://www.youtube.com/watch?v=VXzrCr0RLm4
it complies with the site you gave, it puts a load on the PSU allowing it to start.

thanks for the advice i'll get on with those checks on the you tube vid. i think it may be the mobo aswell as i tried a new psu and still no start up but no blown fuse

Member Avatar for Bob_180_Bob

Hi again,
A new PSU and the fuse did not blow???? Something was causing the fuse to blow, you change the power supply and .... I can only guess that what was wrong with the power supply caused a fault in the mobo and that is still there. I think its time to let a repair tech look at it and advise you what is required.

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