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#193020 - 03/15/10 10:24 PM Bulging Capacitors
packrat56 Offline
Member

Registered: 03/03/08
Posts: 76
Loc: MT, U.S.
This is actually something I got to see firsthand after an old computer I had did an auto-shutdown due to an overheated CPU. I thought it was the fan at first, but the fan still works so my next guess was dust causing hot spots in the heat sink. I then noticed some capacitors on the motherboard were bulging, the way I understand it is that a budging capacitor can mean the component is close to failure.

What causes this to occur? Is it just normal wear or does it has to with abnormal voltages?
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#193021 - 03/15/10 10:30 PM Re: Bulging Capacitors [Re: packrat56]
packrat56 Offline
Member

Registered: 03/03/08
Posts: 76
Loc: MT, U.S.
Strange, the motherboard to my old windows 98 has now outlasted the motherboard for a windows Xp.


Edited by packrat56 (03/15/10 10:30 PM)
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#193023 - 03/15/10 10:52 PM Re: Bulging Capacitors [Re: packrat56]
WESTUPLACE Offline
Member

Registered: 03/29/04
Posts: 252
Loc: Kingwood, TX USA
I replace lots of bad caps on motherboards. Most will split and leak out the top. I work on security DVRs. They use a standard motherboard, different brands, all have shown failure in the electrolytic caps. Different problems will develop, depending on what failed. Take a good soldering iron and great care but they can be replaced. Most are 6.5v 1000, 1500 or 2200uf. If your computer is running slow or has booting problems, check the caps. I have replaced 50 or more last year. Most of these machines run 24-7, which may be why I see so much failure. They also fail on video cards. Sometimes its cheaper to buy a new card than replace the caps. Robert

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#193025 - 03/15/10 11:13 PM Re: Bulging Capacitors [Re: WESTUPLACE]
packrat56 Offline
Member

Registered: 03/03/08
Posts: 76
Loc: MT, U.S.
Thanks WESTUPLACE, but unfortunately when I tried to pull the fan off to check the heat sink I didn't release the lock-tabs and it took the heat sink and the CPU with it. One of the pins on the CPU got bent when I tried to put the CPU and heat sink back in.

I'm thinking that the oveheating of the CPU may somehow be connected to the capacitors bulging.


Edited by packrat56 (03/15/10 11:16 PM)
_________________________
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#193028 - 03/16/10 10:18 AM Re: Bulging Capacitors [Re: packrat56]
SteveFehr Offline
Member

Registered: 03/19/05
Posts: 1192
Loc: Chesapeake, VA
Electrolytic capacitors are a failure item, they simply have a finite life span and eventually fail. Failures typically start to occur at around 5 years, but it depends on a lot of things- ambient conditions, power quality, etc.

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#193060 - 03/17/10 06:14 PM Re: Bulging Capacitors [Re: SteveFehr]
Alan Belson Offline
Member

Registered: 03/23/05
Posts: 1801
Loc: Mayenne N. France
Bigger capacitors can also fail in this way. Here's a 60uf from one of a pair of 3 hp single-phase motors running a 440v 3-phase generator. It had been getting a hammering when I let a couple of bozos loose on a big planer as a favor. They kept stalling and restarting it, too stupid to grasp the concept of a mechanical starting clutch. This was the result, [2007 pic]:



I fitted a new cap, no visible smoke let out! The other motor was apparently undamaged by the incident. Both have continued to run OK for the last couple of years .
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#193062 - 03/17/10 06:36 PM Re: Bulging Capacitors [Re: Alan Belson]
Alan Belson Offline
Member

Registered: 03/23/05
Posts: 1801
Loc: Mayenne N. France
Here's my set up, duplex 230v 3 hp motors running a 440v 3 phase generator with 1:1 vee-belt drive.



[The planer will not start, even with star delta, on 6hp gross output - it's a 20" beast with a 70 lb cutter block running @ 4500 rpm. I fitted a foot operated-clutch to ease her up to speed. The motor is 7.5hp, but I restrict the power by taking lighter cuts.]
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#193063 - 03/17/10 07:10 PM Re: Bulging Capacitors [Re: Alan Belson]
frenchelectrican Offline

Member

Registered: 02/06/03
Posts: 938
Loc: Wi/ Paris France { France for ...
The way you describe the planer that is pretty good size unit I have a 16 inch unit but unforetally it is not a electrique unit it is diesel driven but I put in a shear bolts in case someone jammed with hardwood and stall it.

{ it did happend couple time allready }

I know how long it take to get up to the running speed and I have one of my customer he have very serious sized planer IIRC it will take up to 48 inches that one have 2 motors in there one for planer head the second motor for feed drive { that one is a DC motor } the planer motor itself is 30HP that thing really screams once it get up running speed.

Merci,Marc
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#193064 - 03/17/10 07:44 PM Re: Bulging Capacitors [Re: frenchelectrican]
packrat56 Offline
Member

Registered: 03/03/08
Posts: 76
Loc: MT, U.S.
Gee Alan, that was a motor starting capacitor? I didn't know it could happen in commercial capacitors.
_________________________
I have a sense of adventure, I just keep it leashed with common sense.

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#193073 - 03/18/10 07:16 AM Re: Bulging Capacitors [Re: packrat56]
Alan Belson Offline
Member

Registered: 03/23/05
Posts: 1801
Loc: Mayenne N. France

Here's my post from April 2005 describing some of my machines, which are almost all renovation projects.

My memory is not what it was, and I got some of the details wrong, it's a 6kw alternator.

The Robinson planer was bought to France in about 1992 after our work's carpentry shop closed down in the recession at that time. Funnily enough, I also originally ran it with a small diesel engine till I made an electrical conversion in 2004/5. The main problem was smoke from the stub exhaust and the noise - it was a hand cranked single cylinder job out of a Chinese tractor! Still got it [somewhere].

http://www.electrical-contractor.net/for...html#Post120645


Edited by Alan Belson (03/18/10 07:25 AM)
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