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Motherboard cap's issues

One of my motherboards quit working, the effect being video corruption like issues and lock up. I looked at the motherboard and noticed 3 1000uF/16.3V caps were bad(all the tops were bowed out and one had some black residue below it). I replaced them with one 1000uF/100V cap since they were all in parallel. This allowed the computer to function normally again but the cap is getting rather hot(obviously the issue before) and will eventually fail again.

Of course I already have a new MB on the way but I'm curious as to what is causing this as I imagine it is an easy fix. Something seems to be either shorting out or supplying a rather large voltage. The caps are near some large mosfets which obivously have something to do with the cpu power(they are near the extra V2 connector that gives the cpu more juice).

Any ideas what is the most likely cause of such an issue? My guess is either the mosfets, something causing a short, or potentially a cpu issue(it is not overclocked but something may have failed and put it in such a mode causing excess power usage). I have tried different power supplies and graphics cards with the similar issues. I've checked the mosfets near the caps and they all look fine although I'm not really sure what exactly there function is(such as regulation or current limiting, etc...)

Reply to
Jon Slaughter
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If they were all in parallel, you should have fitted 3 x 1000 uf 16V !!! They have to be low ESR types, preferably 105C rated...

Reply to
TTman

Probably switching regulator ripple current, not excessive voltage. You need three (or more!) caps with low ESR, rated for lots of ripple current. Cooling air would help, too.

The original caps were probably junk.

John

Reply to
John Larkin

Never heard of low ESR caps?

The issue before is simply bad quality. Loads of computers suffer from this problem.

--
Failure does not prove something is impossible, failure simply
indicates you are not using the right tools...
nico@nctdevpuntnl (punt=.)
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Reply to
Nico Coesel

Yeah, I know about the bad caps... some chinese company stole some formula but forgot or missed one key component and made a bunch of bad caps...

I know about the ESR but I figured it shouldn't matter too much and seems to work fine. The cap was getting hot by touch but I put a small fan over it and it is pretty cool. This should work fine until the new MB arrives.

Reply to
Jon Slaughter

I have had two motherboards and a power supply from reputable manufacturers fail on me due to capacitor problems in the past year. The capacitors don't fail in the spectacular fashion that the "capacitor plague" caps I have seen pics of do, and there's no obvious signs of damage to the caps, but they just kind of quietly go open circuit. I'm wondering if there's anything I'm doing incorrectly in the construction of these computers that might be causing premature failure. I always use dust filters on the air intakes of the system, and they're kept cool with several fans (more fans than I'd like, really). Temperature logging on one of the systems showed that the board was always well within safe limits, though I don't know about the power supply. If I built hundreds of computers a year professionally I'd just chalk it up to probability, but I only build a couple for myself and family.

Recently I purchased a motherboard that had all organic polymer capacitors on board as one of its selling features. I bought the board based on other specs and actually didn't know about this feature until it arrived, but it made me curious: does it actually lead to a more reliable board, or are organic polymer capacitors just as likely to be of poor quality and fail but in different and unique ways from their liquid electrolyte cousins?

Reply to
Bitrex

You should get out more.

Reply to
mike

The polymers have very low ESR, so should run cool. And they have no liquid inside to diffuse out. I'd expect them to be more reliable than wet alums in high ripple current situations. But that's a guess.

The polymers that I've tested have very low leakage up to about 2x rated voltage, then abruptly fail shorted.

John

Reply to
John Larkin

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"The polymers that I've tested have very low leakage up to about 2x rated voltage, then abruptly fail shorted.

John "

I clearly have not been having enough 'fun' with my capacitors.

George H.

Reply to
George Herold

Nico Coesel Inscribed thus:

Those caps were 1000uf @ 6.3 volts not 16 !

Parallelling the caps is done for a reason. Ohms law, R's in parallel. Each cap has an effective ESR.

Its getting hot because it is having to cope with very high currents through it. It may well explode, resulting in a destroyed M/B.

Google "bad caps" !

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Best Regards:
                Baron.
Reply to
baron

If you had put the 'right' caps in you wouldn't NEED a new MB.

Reply to
WangoTango

When my HP computer quit, I replaced 7 bad caps, about year ago, all is well. I ordered them from

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Mike

Reply to
amdx

John Larkin a écrit :

either

not

No worries, they are protected by that big Pentium zener...

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Thanks,
Fred.
Reply to
Fred Bartoli

like

either

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I like to test parts to destruction, to see how much margin we have. I've made lots of money by pushing parts well past their abs max ratings.

John

Reply to
John Larkin

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Yeah, where else can you get a 0.8 volt, 150 watt zener?

John

Reply to
John Larkin

These are used switching power supplies. ESR matters a lot. The ripple current in the capacitor is faily high and will heat up a capacitor if the ESR is too high. You need to get good quality, low ESR capacitors. Digi Key and Mouser have many to choose from. Most computer equipment use poor quality or high ESR electrolytics to save a penny or two. Since the caps will die after the warranty, they get to sell you another product. I have fixed a handful of LCD monitors with bulging capacitors over the past few years.

Reply to
qrk

qrk wrote in news: snipped-for-privacy@4ax.com:

eventually,the power supply controller will shut the PS down because of the excess load from bad caps.First,you'll get the "burst" mode,as it tries to restart again and again.

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Jim Yanik
jyanik
at
localnet
dot com
Reply to
Jim Yanik

a

to

If it didn't matter about ESR, why would the caps be built and specified? They matter a lot as evidenced by your new ready to fail overheating junky caps.

G=B2

Reply to
Glenn Gundlach

What you and other tards don't seem to get is that I have a replacement board comming monday as I already stated. So what is the point of ordering low ESR caps and paralleling them when I'm going to get a new board and using one cap worked just fine. Sure it was getting hot but I put a fan over it and it will do.

What part of "This should work fine until the new MB arrives" do you guys not get?

Reply to
Jon Slaughter

What part of doing things right don't YOU get? Or do you do everything half assed?

--
Greed is the root of all eBay.
Reply to
Michael A. Terrell

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