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Soyo tualatin motherboard started to smoke

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First post, by Cga.8086

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Sad day today for me, the motherboard i always used for testing , soyo 7vba133u was giving me problems. I connected everything as usual and there as no post.

Then i tried the usual, replacing the ram, replacing the agp card, replacing the agp with pci, reseting bios.
and then...i smell smoke, and i see a small line of smoke comming near the memory area. I thought it was one of those bad brand small capacitors. but then looking at sunlight i saw this shit

that component somehow failed, or other component made it fail. notice how that ic made some kind of little mountain on one side.

the chip looks like it has markings F P22AF FDS 893DA , but its hard to read. Can this be repaired ? or it is very difficult to get and program the IC with what it should have?

tuala.jpg

Reply 1 of 6, by dosgamer

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Check the markings again. It could be an FDS8934A:

https://www.mouser.com/ds/2/149/FDS8934A-1008457.pdf

It's not an IC, it's a P-FET. The "Q" label is a clue. Probably part of some switching regulator circuit.

They're not expensive, just get a handful and replace it. But before you solder the new one in, check if the thing it's supposed to switch isn't shorted out.

Coppermine Celeron 800 @ 1.12GHz (8x140) - Asus P2B Rev. 1.12 - 256MB PC133 CL2 - Voodoo5 5500 AGP - SB AWE64 CT4520 - Roland SCC-1 - Intel Pro/1000GT - 1.44MB Floppy - ATAPI ZIP 100 - 120GB IDE - DVD-ROM - DVD-R/RW/RAM - Win98SE

Reply 2 of 6, by Cga.8086

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dosgamer wrote:
Check the markings again. It could be an FDS8934A: […]
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Check the markings again. It could be an FDS8934A:

https://www.mouser.com/ds/2/149/FDS8934A-1008457.pdf

It's not an IC, it's a P-FET. The "Q" label is a clue. Probably part of some switching regulator circuit.

They're not expensive, just get a handful and replace it. But before you solder the new one in, check if the thing it's supposed to switch isn't shorted out.

hey, i sent you a private message, you seem to know a lot about electronics and i wanted your advise on how to check.
i checked again and it is ... FDS6930A

missed a number.

Reply 3 of 6, by Cga.8086

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Ok so the part is shorted
i was checking with a multimeter and this leg on the bottom has continuity with all 4 legs on the top
. In a good working one it should have continuity with only 2 legs on the top.

Do these things happen often? im not sure what else should i check.

Screenshot-20181105-093012.jpg

Reply 4 of 6, by Cga.8086

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hey guys, today the package from china is finally here
with 5 replacement SOP-8 mosfets Fairchild 6930B

my idea is to have the motherboard fixed, seems like an easy soldering job of 8 legs

But i want to know. Mosfets burn by themselves? or there is another component that could be the reason why it burned?
i just hope after i finish it doesnt burn at once.

Reply 6 of 6, by Cga.8086

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sadly
i spent some time removing the old mosfet and placing the new mosfet

Motherboard turns on and there is no video, tried with different cpus, memory and AGP cards.
seems like when it burned some other components were damaged.

i also used a PCI/ISA POST card to see if it gave any error and nothing was shown on it.

I will just throw it away.

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