Fixing short circuited laptop motherboard. Where to start?

Discussion in 'General Electronics Chat' started by Srivas, Sep 14, 2009.

  1. Srivas

    Thread Starter New Member

    Sep 14, 2009
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    Hi.

    I have a laptop, which stopped working. When connecting to the ac, the adaptor light starts blinking and laptop wont power on, also without the battery. While searching out the net, I found out that the motherboard is probably short circuited. I didn't open the laptop yet, but what's happening is that when the light is blinking on the adapter, then on the same time near the power socket in the laptop I can hear a ticking sound. I would like to try to fix the motherboard myself, since nobody is offering such a service anyway, atleast not in Estonia, and I dont want to spend extra money. My question is that from where should I start to look for the problem? And does anyone have experiece with such an issue before?

    Thanks.
     
  2. studiot

    AAC Fanatic!

    Nov 9, 2007
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    I should prove that the power supply is actually OK before fiddling with the laptop. They are much more likely to fail than the laptop itself.

    What are your resources and skills?
     
  3. dushuai

    New Member

    Sep 9, 2009
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    Making such decision should be more clear-headed,do you have some pro hardware skills,do you have essential tools,and any one would help you ?
    The MOBO is easily broken,be care!attension on short circuit :)
     
  4. steinar96

    Active Member

    Apr 18, 2009
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    The odds of you fixing your mobo if it's damaged are quite slim. Modern motherboards are made mostly of surface mount components. If some of them are damaged then it's likely you have to buy a new mobo. Unless you have access to a reflow station and extra components
     
  5. Srivas

    Thread Starter New Member

    Sep 14, 2009
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    I already tried another adapter, same thing.

    I have very few skills in hardware, I've done some basic soldering and cable repairing. But I know from experience that everything can be fixed if you really want to. I'm ready to give a try, if it's worth it. As far as help goes, I could always find everything from the internet, especially when asking experienced people like you who can give a direction to go and good advice also. Besides that my father is an engineer and could help me out with instruments.

    And there is nothing to lose, it's not a brand new laptop. It's a fujitsu-siemens amilo L1300, but I would rather try to fix it and use it that throw in the trash, since new mobo costs more than the laptop itself.
     
  6. studiot

    AAC Fanatic!

    Nov 9, 2007
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  7. Srivas

    Thread Starter New Member

    Sep 14, 2009
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    Because my friend has exactly the same laptop and its working there. I already wrote to Fujitsu forum some time ago, but no response.
     
  8. studiot

    AAC Fanatic!

    Nov 9, 2007
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    Very often it is only the internal power socket that needs resoldering /replacing on laptops. They often take quite a beating.

    I can't remember how the lifebook one works, some are on a separate sub board, some directly on the motherboard. You would need to trace the input through the socket. Then to an internal surface mount regulator, which also sometimes fails, but is repairable.

    Dismantling a laptop down to the power supply is not a task for the inexperienced, have any of your friends ever done one?

    Search online for 'dismantling a lifebook' there's lot's of entries.
     
  9. Externet

    AAC Fanatic!

    Nov 29, 2005
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    NOT simple for the unexperienced.
    But hey, it is already broken; the worst is to break it even more.

    Remove covers to access the area where the adapter plugs to, and measure continuity between the supply terminals, trying to draw the schematic of what you can discern.

    Check for shorted electrolytic capacitors in the area of power regulation if you can recognize the circuitry.
    The continuity meter is the right tool; some suspect components have to be removed to confirm they are/are not good.

    If everything fails and you are ready to throw the towel, briefly apply 12V from a car battery and the smoke will come from the shorted component. You will not be able to repack back the lost smoke. If it burns completely you will not be able to identify it, so take some close-up pictures before. That component needed to be replaced anyway. It is a very brute force way to do it as last resource and traces may vaporize; so be prepared for bad news.
    Come back with findings.

    Miguel
     
  10. Srivas

    Thread Starter New Member

    Sep 14, 2009
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    Thank you, I'll start working!
     
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