Discussion Shorted fan pins damage repair

[B>K>P]

Having accidentally shorted the fan header on my computer resulting in complete death, I managed to get it going again as follows.
I first confirmed the power supply was still OK by removing the 24 pin plug and shorting pin 16 (blue wire) to the earth on either side (Pins 15 or 17) with power applied. The fan ran and all voltages were working. Next I removed a small amount of insulation from both wires just back from the plug and soldered a short length of wire to each, then insulated the join. The plug was then returned to the mother board and the power provided to the power supply, the computer still did not work, I then touched the bared ends of the wires added. On touching the wires together the computer started and booted up. After this the computer will now start from the normal start button and is back to working normally.
This probably wont work in all cases but it's easy and worth a try'.

 

[Misgar]

Does that mean the fault current was high enough to melt some of the wires in the 24-way ATX power cable? I would expect the OCP in a high quality PSU to trip before significant cable insulation melting occurred.

If tens or hundreds of Amps from the main 12V rail have short circuited down to the ground plane on the motherboard via a fan header, who knows what's "cooked off" in there.

I'd treat the PSU with caution and the motherboard too, if a fan header was involved in the short circuit. It's not easy to tell from your description.

If the insulation on the external 24-way ATX cable has melted, there could be similar damage hidden inside the PSU. Chuck it in the bin.

 

[B>K>P]

Does that mean the fault current was high enough to melt some of the wires in the 24-way ATX power cable? I would expect the OCP in a high quality PSU to trip before significant cable insulation melting occurred.

If tens or hundreds of Amps from the main 12V rail have short circuited down to the ground plane on the motherboard via a fan header, who knows what's "cooked off" in there.

I'd treat the PSU with caution and the motherboard too, if a fan header was involved in the short circuit. It's not easy to tell from your description.

If the insulation on the external 24-way ATX cable has melted, there could be similar damage hidden inside the PSU. Chuck it in the bin.

 

[B>K>P]

Hi ...You are a bit off track here, in this case the short was instantaneous from a touch with a multimeter probe, resulting in a tiny spark and sudden shut down. No physical damage was done. Shorting pin 16 (can be either a blue wire or green)is normally done from the start button, through the mother board from a current controlled low voltage output from the power supply, doing the same job via the two wires just takes the motherboard out of the picture. As far as I know all computer power supplies have all their output current controlled and are quite safe except in rare disasters.
B>K>P

 

[Misgar]

Sorry. My mistake. When you said your system suffered "complete death" after you "accidentally shorted out the fan header" it sounded like you'd had a total melt down.

Good to hear it wasn't anywhere near as bad as it sounded.

I imagined melted insulation and blackened components, which is what usually happens when 'magic smoke' comes out of a PSU.