Monday, 16 January 2012

Repairing a dying motherboard

We have two servers at our house, one is for MythTV while the other is a traditional domain controller. One day the domain controller stopped responding, it turned out the motherboard was dying.

Like any good geek I used this opportunity to upgrade the hardware but I lazily left the faulty motherboard on a desk and forgot about for several months. A few days ago I picked it up and happened to notice a handful of bulging capacitors.

I've read many tales of capacitors failing and how replacing them can bring electronics back to life but never had first hand experience. I saw this as my opportunity to attempt something risky... without risk.


I ordered a bunch of replacement capacitors, some no-clean flux and solder wick and sat back patiently awaiting their delivery.

In the following image you can see the two capacitors closest to the camera are bulging at the top. If you look carefully you may be able to see a few others in that picture exhibiting the same symptom.


If they are subject to high temperatures the fluid inside these 'little towers' evaporates, turning to gas, increasing pressure inside causing the casing to bulge. As you can see, this area of the motherboard is where the ATX cable attaches so these capacitors are likely involved in voltage regulation, an area often synonymous with high temperatures.

After replacing the first capacitor I re-tested the board. It booted! I had not expected this at all.  It seems with just one replacement the board was operational again. But I could see there were several other failing parts and I didn't want to have to redo my work so I unplugged the unit and set out replacing all the others too.


All the failing caps were of the same rating so I suspect they were from a bad batch. There are 11 of this particular capacitor on the motherboard but I chose only to replace the six around the ATX connector. Replacing the others would have involved removing a large heatsink and none of the rest had any visible damage at all.

I'm happy to report that everything went swimmingly. The board has been running for a little over a day now with no problems. In fact, I was so pleased with myself that I had to instantly go show my wife what I had achieved with no training in electronics and a £5 soldering iron, just determination and a steady hand.

She was nonchalant.


The new capacitors are easily identified as they are brown while the OEM units are black.

23 comments:

  1. Well, great job. No harm in trying.
    Nothing could be broken more than what was already broken, and its a good exercise for future bulgy electrolyte replacements ;-)

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    Replies
    1. Things can always be broken more than they are already broken. If you have already accepted the device is a loss, it just doesn't matter as much.

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    2. Cleverly phrased, Anon, I like that.

      I think you've both correctly deduced I had written the board off; it was surplus to requirements.

      Now it's a bonus to have a spare system for server experiments :)

      Delete
  2. I'm just getting ready to do a full capacitor replacement job on an old Dell GX280 Optiplex I picked up recently. The PC runs well, but it has a handful of bulging capacitors I just can't trust. I received several non-working 19" Viewsonic LCD monitors last summer, and all it took was a capacitor kit from eBay for each monitor to get them working. Easy-peasy and inexpensive ($13.00 CDN per monitor). eBay is one's friend for these sort of "recycling" projects.

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    Replies
    1. That seems to be a problem with the Dell Optiplex GX280 and GX270's. I recently replaced about 60 capacitors on 14 GX270's with another two machines to go.
      It appears Dell used faulty capacitors in these machines and then told it's employees to blame it on the customer if they were to call in for tech support. Read about it here: http://www.tomshardware.com/news/optiplex-capacitor-lawsuit-failure-defect,10763.html

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  3. be sure to use low esr (impedance) and high temperature (105 degree ) capacitors ... if you use another type of caps it will work but their life span will be greatly dimished

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  4. Personally, I never look at the temperature ratings. Only make sure the impedance is the same as the original and the voltage rating is equal or higher. Most electronic stores won't carry 6.3v capacitors, but will have 16v or 25v. Works just as well in my tests, but you could need more work when the pins are really bigger (use dead bug technique, don't drill !). You can also ask computer repair stores for broken hardware to get free capacitors : reusing > recycling. Worked about 80% of the time with over 30 repairs for me, and I never had to redo a job (screens + motherboards).

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  5. Go to digikey and buy Panasonic FM or FC caps. They are damn good low-ESR caps and won't take a dump yet again in the future.

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  6. You'll find this trick is also useful for that LCD HDTV you have.

    In mass produced electronics they tend to use the cheapest passive components they can find. Replacing them with something just a little better yields fantastic results.

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  7. I've revived 3 lcd's about 12 motherboards and enough CRT's to fill a dump over the years and the reaction is always the same, shock. Always shocking when an expensive to replace article is renewed with a 50 cent item and five minutes of work. The best one was reviving my father in laws satellite receiver so my mother in law didn't have to miss E.R. years ago. She was bumming around the house and generally pissed at the world because they couldn't buy a new one fast enough. The father in law wanted to kiss me when the receiver fired up the mother in law just wanted us all to shut up lol

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  8. You must use same ESR or lower (but not too much lower), and same ripple current rating or higher for the replacements, and they must be of good brand otherwise you are wasting your time.

    You can NOT simply use "any old capacitor" especially NOT cheap ones from places such as Radio Shack.


    Ps: Note also that just because the capacitor isn't bulging does not mean it isn't bad.

    ReplyDelete
  9. Thanks for all the comments, they tipped me off that perhaps I had been featured on hackaday.

    I used long life capacitors, rated for 3000hrs at 105°C. I plan to use this board in quite an enclosed space with no airflow so I figured the extra lifespan over the more common 2000hrs/105°C caps would be beneficial.

    Agent24, I totally agree with your PS. This was the most precision soldering job I've ever attempted though so I didn't want to push my luck. With each component the likelihood that I would nerf the board increased. I'm happy with the compromise :)

    Again, thanks for the comments and tips.

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  10. If you're trying to do this for monitors (I've done three) there are sites that sell kits for certain brands/models that are notorious for capacitors going bad.

    I mention this as a FYI because it eliminates some of the guess work of finding the right capacitors. Maybe they exist for other electronics, but I've never looked.

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  11. I totally love your comment about your wife :D I know exactly the feeling!

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  12. Many of the early MikroTiks had this problem, easily solved using the same methods.

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  13. www.badcaps.net has tons of info on this subject.

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  14. "I was so pleased with myself that I had to instantly go show my wife what I had achieved with no training in electronics and a £5 soldering iron, just determination and a steady hand.

    She was nonchalant."


    Hahah true story.
    been there a couple of times. breaks my heart everytime =(

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  15. Hey,

    Great bit of repairing work here. Really impressed. Do you have an email I can catch you on? I have a few questions id like to ask. My email is rgibson(a)farnell(dot)com

    Thanks

    Ryan

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  16. google "capacitor plague" and all will be explained.

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  17. Hi, I ordered new capacitors from eBay for my motherboard and trying to take out the old capacitors with my 40W and the solder on the board just doesn't wanna melt. grrr
    Do I have to buy a better soldering iron?
    I don't have flux, reason why I cannot have that to melt?
    Would be good to add on this tutorial which soldering iron you used for the repair.
    Thanks for help.
    Steven

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  18. If you are tired from visiting different repairing center for repairing your motherboard then visit once only the BGA workstation which are providing you excellent services of motherboard chip repairing.
    Reballing kit

    ReplyDelete
  19. This is sch a nice read and i really like your idea of repairing a dying motherboard. these types of repairing always look so interesting and when we achieve the goal we feel great same lie happens with you.
    full auto BGA

    ReplyDelete