Replace capacitor in computer board

in this instructable we'll replace failed capacitor in PC mainboard

the mainboard here is from friend's computer. it crashed randomly for few months and now it does not allways complete startup

this may - and in this board is - caused by failed capacitor. capacitors stabilize the power to components in the computer. when they go bad the computer gets spikes or 'flickering' voltage that makes it malfunction and damages it

Step 1: Tools

new low ESR (low internal resistance) cap

pin from message board

sharp soldering tool 30 W (more may be better but dont overkill) and soldering stuff

Comments

[rbennett8]

first off this is not a hack it is simply a repair there is a difference

and you need a power supply tester and a mother board pci test card they will tell you whats wrong with computer

[zack247]

a pentium 4, nice. im gonna do this with a socket 370 mobo. don't know what happened to it but i just have to find 10 more capacitors and i can try and hope... its a really great mobo and i wnna put a celeron into it

[zack247]

can i replace a 6.3v with a 16v capacitor? or will that do damage?

[app0]

It shouldn't, but you better go and find the exact one and ALWAYS BUY BRANDED CAPACITORS like Rubycon, Sanyo, Panasonic etc.

[zack247]

thanks for letting me know.

just in case anyone wanted to know, the board did work, until the power supply i had hooked up to it literally blew out. there are no bad caps and now i dont know whats wrong with it because changing the cpu, ram, and resetting the bios dont do anything. it just keeps beeping.

[app0]

Can you tell me who is the bios manufacturer and the beep pattern?

[zack247]

i dont know the bios manufacturer, but it is a ibm pro 300_afp motherboard, and it just keeps beeping, it doesn't stop. nothing shows on the screen either.

[app0]

Check what's written on a label on a BIOS chip. A photo would also be great.

[zack247]

i'll see if i can get a photo of it. i also might have gotten the board name wrong.

[app0]

Usually on "default boards" (nonames) or "ideal boards" (complies with all standards of AT/ATX) a continuous beep is a PSU/CPU problem, however it might be different. Also be sure it comes from the speaker, not from parts.

[zack247]

here: i mistyped the model number, it should be Pro300A_AFP.
a quick google search and i found the same board as i have got.

http://www.google.ca/images?hl=en&gbv=2&biw=1003&bih=583&tbs=isch%3A1&sa=1&q=pro300a_afp&aq=f&aqi=&aql=&oq=

the sticker on the bios says:
UNITY
IBM (C) 2001
REV .09

thats all i could find, let me know if i need anything else.

[app0]

Oh noez the Instructables comment script cuts out the TAB's

[app0]

IBM Desktop BIOS Beep Codes:

1 short Normal POST System is booting properly
2 short Initialization error - Error code is displayed
1 long, 1 short System board error
1 long, 2 short Video adapter error
1 long, 3 short EGA/VGA adapter error
3 long 3270 keyboard adapter error
Continuous Power supply error - Replace the power supply
999s Power supply error - Replace the power supply
No beep Power supply failure - Replace the power supply

Here you go

[zack247]

really? but the power suppkies work fine on any other board, i'll try again, but do you think maybe there is a chip burnt out on the board thats telling the motherboard the wrong thing?

[zack247]

well it cant be a cpu problem, i tried multiple cpus and got the same problem, same with PSU's.

It is definitely coming from the speaker on-board, i am still not sure whats wrong with it yet, i am going to see if i got the model right, i might have mistyped it.

[gurtek]

nice and useful............

[bwpatton1]

is this from a dell optiplex? Gx 260 possibly

[bwpatton1]

Hey, Itz an Energy Star you can get a tax deduction for that i think.....

[11010010110]

shutting down the computer / monitor when not in use (instead of standby etc) can save way more energy than energy star compliance using minimal hardware (like onboad video card and not agp / pcie one) saves some energy too i am not from the us. as far as i know energy star gives tax refund only in the us

[11010010110]

nope its gigabyte GA-8IG1000MK in a locally assembled pc without company name

[bwpatton1]

oh, cuz the optiplex had problems with capacitors on the MOBO

[11010010110]

i have a second hand 2001 GX150 pentium 3 and its capacitors are ok. no experience with newer dells replacing capacitors is done the same way in all computers

[navarrofeds]

good Instructable ! I have a computer that will not pass post and I think its the mobo possibly a fried cap. I am waiting on a vid card to try that and have tried everything else. just wanted to say thanks this might com in handy

[NachoMahma]

. Good job. . Do you really have to remove the flux (step 9)? It was never a problem for me (but the last mobo I touched with a soldering iron had an 8088 processor running at 4.77MHz).

[11010010110]

there is conductive flux. i discovered it by accident i was working on an audio project and could not figure why the opamps are stuck in saturation. flux between 2 ajacent entries of the opamp (vcc and + in) had a resistance of ~ 6 K ohm. more than enough to make trouble. i scratched it away and it worked it can be left as is if its just across the capacitor (it may take some leak current but if its only vcc and earth the computer won't mind). i'd still remove it if there is no risk to damage the board in the process

[NachoMahma]

. Good to know. I'll keep that in mind if I ever do any more soldering.

[philipster]

good but too many cautions u have to take into account theres resisters that can be affected by the hear of soldering iron

[11010010110]

thats why you should be cautious when you feel the heat spread over the board

[mcraghead]

I presided over a school computer lab with a "bad batch" of Dells that had bad caps...
I found this site helpful: badcaps.net

[AndyGadget]

There was a lot of faulty capacitors used in computers and many other types of equipment a few years ago. These would fail after a couple of years of use. My company had a large batch of IBM PCs which all died sooner or later with bulging mobo caps. (Wiki info HERE )
Random lockups are the most common symptom as the internal resistance falls and the ripple on the power lines increases.