Fixing motherboards - bad caps?

[Half-Saint]

I got a bunch of motherboards that presumably don't work. I haven't tested them yet but at least 5 of them have bulging/leaking caps. The other 7 look fine on the outside.

How can I verify that these boards also just need recapping?

Thanks,
SainT

[c_hegge]

Re: Fixing motherboards - bad caps?

Re-cap them and see if they work. That's what I do. If it works fine after the re-cap, that's all that was wrong. Otherwise, there are other problems.

Also, just because the caps look good doesn't mean they are. It's very common for caps to fail without showing it, so the 7 boards which look good may have bad caps.

[PCBONEZ]

Re: Fixing motherboards - bad caps?

on: "just because the caps look good doesn't mean they are".
OST brand and chemicon KZG and KZJ are notorious for failing without bloating.
Any brand -can- fail without bloating, it's just not as common as those mentioned.

Look at the chipset for signs of melting [holes, lumps or shinny spots] which can indicate a PSU or caps problem burned out the chipset.
Check the MOSFETs for similar problems.
- If you don't have those problems then just try a recap.

.

[c_hegge]

Re: Fixing motherboards - bad caps?

Add teapo to the list of non-bloaters. I was once given a board with entirely teapo. None were bulged, but the board wouldn't POST. It came good after a re-cap.

Also had a board with entirely OST before. Same symptom, same fix.

[kaniki]

Re: Fixing motherboards - bad caps?

I would say just add all caps to that list.. especially the china made ones.. I have a G Force 2 PCI card sitting here that i tested the caps while on the card. supposed to be 1000 uf caps, one tested around 300 uf. and no bloating either. that brand is something like szwx (in cursive) is what it looks like on the cap. dont know, never heard of it before. point is, any brand can fail without bloating. never take any brand for granted that it will bloat when gone bad.

as for the recapping.. just recap. if the board is bad, just take the good caps off and save them for another board later. you will just have a few spares lying around for a bit but would not be any harm in trying it.

[Half-Saint]

Re: Fixing motherboards - bad caps?

Last night I recapped two of the mentioned motherboards. None of the boards work after the recap. One turned on but stopped working after 2 seconds. No signs of life afterwards. I replaced 15 1000uF 6.3V but may have damaged one solder pad (tube) in the process of removing solder from the hole...

The second board turns on (fans turn) alright but doesn't produce any beeps or video. I replaced all 3300uF 6.3V and all 1500uF 16V caps. Any ideas?

Cheers

[PCBONEZ]

Re: Fixing motherboards - bad caps?

Last night I recapped two of the mentioned motherboards. None of the boards work after the recap. One turned on but stopped working after 2 seconds. No signs of life afterwards. I replaced 15 1000uF 6.3V but may have damaged one solder pad (tube) in the process of removing solder from the hole...

The second board turns on (fans turn) alright but doesn't produce any beeps or video. I replaced all 3300uF 6.3V and all 1500uF 16V caps. Any ideas?

Cheers

Reset the CMOS and try again.
Next time take the battery out while you work on it.
[Little thing everyone forgets to mention.]

[Half-Saint]

Re: Fixing motherboards - bad caps?

I tried resetting the BIOS but it didn't do anything.. I'll try a new battery when I get home.

[PCBONEZ]

Re: Fixing motherboards - bad caps?

A bad battery usually won't prevent booting but a scrambled/corrupted BIOS might.

Inspect the chipset chips.
Look for shinny spots, cracks, or pits.
Those are signs the chipset was blown out.
[Melted or arced and sparked inside.]
Usually happens when cheap PSUs are used and I assume you don't know what these were on before you got them.

.

[Half-Saint]

Re: Fixing motherboards - bad caps?

The north bridge is under a heatsink which I won't bother removing. The other components look fine visually. It's a shame because this Soyo used to be a nice board... clearing the CMOS again didn't work. Funny thing is I can power off the board, if I hold the power button for 5 seconds, like usual.

[Half-Saint]

Re: Fixing motherboards - bad caps?

The north bridge is under a heatsink which I won't bother removing. The other components look fine visually. It's a shame because this Soyo used to be a nice board... clearing the CMOS again didn't work. Funny thing is I can power off the board, if I hold the power button for 5 seconds, like usual.

[Half-Saint]

Re: Fixing motherboards - bad caps?

I figured it out... the CPU I was using to test the motherboards is dead and I knew that but wasn't paying attention since I just grabbed the first CPU I saw on the shelf. What a mistake!

Well, too late for one of the boards since I already massacred it for parts. The other one will probably work

Cheers!

[PCBONEZ]

Re: Fixing motherboards - bad caps?

Oops!

[severach]

Re: Fixing motherboards - bad caps?

Put an X on the bad part with a Sharpie. If it later turns out to be fine brake clean will remove the mark. Permanent markers aren't permanent for everyone.

[PCBONEZ]

Re: Fixing motherboards - bad caps?

I generally mark bad CPUs with a hammer.

[ratdude747]

Re: Fixing motherboards - bad caps?

I generally mark bad CPUs with a hammer.

i gernerally mark bad ones by leaving them on random shelves and counters... ... bad habit, i know...

[PCBONEZ]

Re: Fixing motherboards - bad caps?

i gernerally mark bad ones by leaving them on random shelves and counters... ... bad habit, i know...

That's how I used to do it.
Then,, one day,,, !!!!!!!!!

[c_hegge]

Re: Fixing motherboards - bad caps?

It's extremely rare for a CPU to fail. I've only seen one fail on it's own. I've seen two or three others fail, but they were either overheated when the fan failed or a clip snapped or they came from PCs which were hit by lightning most of the other parts were also fried.

[PCBONEZ]

Re: Fixing motherboards - bad caps?

It's extremely rare for a CPU to fail. I've only seen one fail on it's own. I've seen two or three others fail, but they were either overheated when the fan failed or a clip snapped or they came from PCs which were hit by lightning most of the other parts were also fried.

Granted.
I've probably only seen one bad one to every 100-200 good ones.
.

[Half-Saint]

Re: Fixing motherboards - bad caps?

Well glad to report the other mainboard (Soyo Dragon) works fine after the recap.

Cheers