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About capacitors for PC motherboards...

Hi folks, new poster, electronically challenged....

I hope you will be kind enough to help me, I face the following problem:

I have a motherboard in one of my PCs that has gone all flakey. It has bad cap syndrome. The low ESR electrolytic aluminium can caps are bulging and leaking. I know that this problem was rife around 2000/2001 but thought it fixed by the time I bought this board, 2003. Sadly not true. The board itself has been, up until the caps failed, an excellent, stable and very useful bit of kit.

I have replaced capacitors on motherboards before with success so am not worried about that side of things. My problem lies in the fact that I live in New Zealand. It seems that it's just about impossible to get a handful of caps the same specs as the ones on the board anywhere. I've found suppliers in the US but not any who will ship *outside* of the US. As I assemble computers for a hobby and used this same model mobo in a few different builds for friends I'm expecting to see others with the same problem soon too.

Ok, so the main caps I need are low ESR, 3,300uF, 6.3v, 10mm can, 5mm lead-spacing (25mm high but that's unimportant, there's room to go higher) electrolytic caps. I can't seem to source these anywhere in this wonderful country of mine. I've been told I can get them in 15mm diameter cans which is unacceptable as there is a row of five tightly satcked together. I've tried for Nichcon and Rubycon first as I hear that these are good caps. The local Nichicon agent said they don't have them ex-stock but could order them in. A minimum order of 2K pieces and a 90-day turn-around! I need 5 for a start, maybe another 20 later. You wouldn't believe how difficult a seemingly easy thing like this has turned out to be.

So, to the advice I'd like: A year or two back, when I first struck motherboards with bad caps a guy I met on a NZ newsgroup offered to get me some suitable caps as part of his next order (which lead me to assume he was "in the trade"). The caps needed for those three mobos I was hoping to fix were the ame spec, 3,300uF 6.2v.... Anyway, the caps he sent me were 2,200

10v and he said the should be fine. He couldn't get the exact match. I went ahead and fitted the caps and the motherboards worked fine. I still have one of them running the PC I use for a stereo/mp3 jukebox that runs 24/7.

The board I'm currently looking to fix is (was) running an Athlon XP3200+ so is still reasonably useful, I was expecting to get a few more years out of it. The boards I repaired before using different spec caps were less valuable so I wasn't so worried if it didn't work. However, I've been told in a local newgroup that, often, caps on a mobo are specced +/- 50 to 100%, that they are 'smoothing' caps. (They are right next to the CPU and the first symptoms was unstable CPU core voltage).

My question to the collective here is: Do you folks think it would be relatively safe to use 2,200 uF caps in this motherboard? It's worth quite a bit more than the others I fixed and I can't afford to make a mistake with it.

Kind regards, and thanks in advance,

--
Shaun.
Reply to
~misfit~
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Graham

Reply to
Eeyore

It's *very* likely that the capacitance is chosen for ripple current capability and not the absolute value. Subbing a smaller capacitance from a top-grade vendor is very likely to do the job just fine.

Graham

Reply to
Eeyore

Try R P Electronics

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Reply to
Homer J Simpson

On Mon, 28 Aug 2006 09:56:23 +1200, "~misfit~" put finger to keyboard and composed:

Farnell have 10V, 12.5mm dia caps at AU$3.67 + GST:

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Alternatively, WES Components, Ashfield NSW, have 10V, 13mm dia, low ESR, Hitano EXR series caps, AU$1.15 including GST (trade).

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The same series has a 6.3V, 3300uF, 10mm dia cap, but WES don't list it in their 2003 catalogue, or their Nov 2005 supplement.

- Franc Zabkar

--
Please remove one 'i' from my address when replying by email.
Reply to
Franc Zabkar

Try

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they're inexpensive, have the biggest stock in the world, and ship internationally. Search for electrolytics, low esr.

BTW you really don't need to get those tiny 10mm size-- you can mount them with up to 1 inch leads no problem and thereby spread them out a bit.

Reply to
Ancient_Hacker

Not very practical to be honest.

Graham

Reply to
Eeyore

Thanks Franc. However, these caps are really bunched up, I *need* them to be

10mm. :-( 
--
Shaun.
Reply to
~misfit~

"These are recovered from almost new motherboards"

No thanks. The board that has bad caps has others around it of the same brand that look just fine but are probably no better, just under less load.

--
Shaun.
Reply to
~misfit~

Thanks. That's what I'd hoped to hear.

--
Shaun.
Reply to
~misfit~

Not at all. I've tried that before on a different mobo, insulating the long leads. Still didn't work, I couldn't get them to fit. There are a bunch of caps (three rows) between the CPU socket and the backplane. No room for big caps on stalks.

--
Shaun.
Reply to
~misfit~

Ok, trying it now. What's with the 'series' column?

Umm, nah. I've tried that before on a board less crowded than this one. Not an option really.

Cheers,

--
Shaun.
Reply to
~misfit~

Thanks, I've checked the site out but seem unable to search for 'low ESR' or find such a category.

Cheers,

--
Shaun.
Reply to
~misfit~

Bullshit. Lower capacitance will reduce the filtering, and cause problems.

--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida
Reply to
Michael A. Terrell

a

capability

At smps frequencies ? You're simply babbling.

Graham

Reply to
Eeyore

On Wed, 30 Aug 2006 00:25:56 +1200, "~misfit~" put finger to keyboard and composed:

Search for EXR3300/6.3 at

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(Hitano agents)

You can get 10 for $40, or 5 for $36, including $15 freight, GST, and a $15 penalty for ordering less than $200 worth of goods. :-(

You may be able to avoid the freight cost if you live near one of their offices:

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- Franc Zabkar

--
Please remove one 'i' from my address when replying by email.
Reply to
Franc Zabkar

A good tech is better than a crappy designer any day. A number of the EEs I've worked with came to the production floor with questions about our older products. They would make written requests for me to test new designs and to qualify new components, or do failure analysis and track failure trends. I had more databooks in my corner of the production floor than most of the engineers kept in their offices. A common question from them was why I didn't have a degree, because I could do their work, and often caught errors in their preliminary work.

--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida
Reply to
Michael A. Terrell

Fine by me.

Designers do know stuff that techs don't though.

Graham

Reply to
Eeyore

" Shuttle FV24 and FV25 Kit Update!!!!!! I ran out of stock on the 10v caps that were needed to make the kits.

3300uF~4700uF 10v caps in a 12.5mm diameter are IMPOSSIBLE to find, and anything larger will not fit the board. I had to temporarily discontinue the kit because I didn't have a FV24 or FV25 motherboard to conduct experiments on. However, early last month, I got one of each, and did some extensive testing and research on it, and discovered the 10v caps were NOT needed. The positions those caps are in only have 2v MAX (VCORE voltage only) at any given time, and the voltage does NOT fluctuate. Why Shuttle used 10v caps is beyond me, but manufacturers have been known to do this in the past.

I recapped them both with Rubycon and Nichicon 3300uF 6.3v, and they've been running 100% reliable under heavy load, and in brutally hot conditions for over a month now. "

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So, Michael, why did they use 10V caps ?

Graham

Reply to
Eeyore

3300uF~4700uF 10v

fit the

or FV25

of each, and

were NOT needed.

given time, and

manufacturers

been running 100%

now. "

Shuttle is a high end board maker. Using the 10 volt caps will ensure their boards live through their warranty period. They aren't trying to make boards for under $500 systemms, so they can spend a couple more cents per electrolytic. I haven't seen a shuttle board with bad electrolytics, so far. I know some do fail, but none have crossed my bench. Hell, I have a Sun workstation in the shop that had all but one of the CPU PS electrolytics fail, and it isn't a cheap computer.

--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida
Reply to
Michael A. Terrell

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