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Repairing Motherboard - Bad Caps?

Posted on 2003-12-01
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My specs: ECS K7S5A mobo, AMD Athlon Tbird 1 GigHZ CPU, 512 Megs DDR Ram (2 sticks), DVDROM, Iomega 100 Zip Drive Internal, Adaptec 2940UW SCSI Adapter, 9 Gig SCSI HDD Internal, 40 Gig IDE HDD 7200RPM, Geforce2 GTS 32 Meg AGP videocard, SB Live! 16 Bit soundcard, 1 Floppy Disk Drive, Onboard LAN NIC Card, L&C 300W PSU (+3.3V/14A, +5V/25A, +12V/10A), APC Power Surge Protector, 1600x1200x32bit Desktop Resolution, Windows 2000 Pro [SP4], ATX Form Factor.  The system can be running for days on end using Peer-2-Peer apps.  Usage includes: MS Visual Studio .NET application development, minimal 3D Games, MP3 playing, web surfing, Peer-2-Peer downloading.  The system is 2 years old.

My ECS K7S5A motherboard with Athlon Tbird 1 GigHZ CPU appears to be dead.  Inspection of the board reveals 4 capacitors with convex tops and brownish stains.  Trying to turn on the system has been strange: Just plugging in a different PSU (250W) while "set to off" causes the CPU Fan to spin momentarily!; Turning on the system sometimes had the CPU Fan running but no POST would appear in fact there doesnt appear to be a video signal; The system wouldnt turn on; The CPU Fan would audibly vary in speed.  On the positive side all peripherals are fine.  The problem seems to be with the motherboard, PSU, and maybe the CPU(?).

I have 2 questions:

[1] How did my motherboard get to be this way?  Did the cheap quality L&C PSU that i have cause this or is this due to bad mobo manufacturing on ECS's part?  Proactive measures I can take would be dilgently pursued if sugested.

[2] I've been to a few websites providing tips on repairing motherboards, the most common being replacing bad capacitors.  Have you had much success with this?  That is, after attempting to replace capacitors have you noticed a complete resurrection of the mobo or a noticeably volatile system?  Is it better to simply buy a new motherboard than to repair a dead one?

Thanks.

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Question by:barkin
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by:slink9
ID: 9849520
It is definitely better to buy a new one.  These things are really tight in the integration of each piece.  It will be hard for you to work in the small area it will require to desolder and resolder these capacitors.  Buy a new mobo/cpu combo.  You will be much happier.
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by:barkin
ID: 9849549
What caused my mobo to be fried like this?  The L&C PSU which was used before the mobo died doesnt appear to be damaged in any way.  I havent been able to plug it into another PC though.
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jhance earned 125 total points
ID: 9849610
In recent years there has literally been an EPIDEMIC of BAD CAPS in PC motherboards, mostly from Taiwan based manufacturers.  Most have been reported to be due to simply defective caps from a major supplier but it's my expert opinion that motherboard manufacturers are simply UNDER spec'ing these parts and creating a problem themselves.  They routinely put caps rated at 5.5V in a 5.0 Volt circuit and this is just a problem waiting to happen.  Why?  Because this is too close to the absolute maximum rating of the cap and causes premature failure, which is what you see with the leakage and "popped" tops.  

So the combination of poor quality caps and poor design practices have made this a VERY common failure.

I've repaired many many motherboards with this problem and it you are moderately skilled in de-soldering/soldering you should be able to do it without too much trouble.  The caps are standard in form factor and I suggest putting new ones in with a larger Voltage rating than what you find originally.  I also suggest that you replace ALL the caps of a similar type at one time since if one is bad, they likely all are and will eventually fail.
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by:jhance
ID: 9849617
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by:jhance
ID: 9849621
Oh, I forgot to mention.  Some motherboard vendors will repair or exchange such a motherboard even if it's out of warranty.  Contact them and complain.  If you get no results, try again and tell them you KNOW about this "dirty" secret!
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by:chicagoan
ID: 9850026
><snip> "less than half"... 4000 hours of continuous ripple current they are rated for.
would this imply a design standard MTBF of 166 days of continuous operation?
kind of throws a new light on the "should I leave my PC on all the time" question

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by:barkin
ID: 9851829
I'm considering: Asus A7V8X-X VIA KT400 or Asus A7N8X-X NF2 as replacement motherboards.  How are these for defective parts / "dirty" capacitors?
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by:barkin
ID: 9852016
The funny thing is my brother's system has the following specs: HP Vectra VL800 system, 720 Meg RDRAM (1.2 Gig actually but it only picks up 720MB), CDRW, DVDROM, P4 1.7 GigHz, 40 Gig HDD IDE, Used to have a 60 Gig HDD installed until it died (Click of Death), 1 Floppy Drive, Silent CPU Fan, 10/100 NIC Card, SB Live soundcard, Uses extrenal 100MB Iomega ZIP Drive, Windows 2000 Pro [SP4].  And all running off a 250W PSU without problems.  How is this possible?  The PC has the same specs as his work's PC including the PSU so his job's tech department felt the PSU adequate i suppose.  AGain, the system is a rock for over 2 years now.  Though the 60 Gig HDD died...
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by:doug_doug
ID: 9854634
As I've said in your other questions, go with the a7n8x-x nf2.  It's a great board, as the reviews have said.  ASUS has been known to make high quality motherboards.  I've personally had good luck with them as far as their customer care goes too.

http://www.hardocp.com/article.html?art=Mzk0LDM=
http://www20.tomshardware.com/motherboard/20021111/index.html
http://www.overclockers.co.nz/ocnz/review.php?id=03boardnforce20asus0000a7n8xx000105
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by:barkin
ID: 9863796
I pulled the 4 blown capacitors from the mobo.  Each reads:

G Luxon, 2200uF  6.3v
LZ105'c
1067(M)

Now, jhance suggested  replacing the offending capacitors with new ones with higher voltage (so > 6.3v).  No problem but what are the other values?  Do i look for capacitors which match the other terms but with > 6.3v?

Thanks.
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by:jhance
ID: 9865470
The only important specs are:

2200 uF
6.3 V

The rest are just manufacturer data.

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