Help me fix a Laptop Motherboard Short

Discussion in 'General Electronics Chat' started by tryin2fixit, Sep 30, 2012.

  1. tryin2fixit

    Thread Starter New Member

    Sep 30, 2012
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    Here's what it looked like when i opened it up.

    [​IMG]

    So I cleaned it with alcohol and heated it with a heat gun on medium heat for 40 min.
    There's still a short somewhere on the mobo. This is where i believe the short to be since it was sticky and black in that area. I used a multimeter and check continuity on the components in the area, with them still on the board.

    I'm not really sure where black gunk came from. I got the mobo like that.
    I tried plugging it in and it's still short.

    When i put the multimeter on the most gunked up button switches the meter shows a short. The other button switches don't show this. I guess the button switches themselves could be the short? Or maybe this caused one of those little things to blow?
    Should i try taking the shorted buttons off and than seeing if it's still short without any button on it?
    [​IMG]
     
    Last edited: Sep 30, 2012
  2. tracecom

    AAC Fanatic!

    Apr 16, 2010
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    I don't think anyone wants to tell you that the motherboard is a lost cause.
     
  3. tryin2fixit

    Thread Starter New Member

    Sep 30, 2012
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    Really? I'm sure someone on here would fix it if it were in their hands.
     
  4. tracecom

    AAC Fanatic!

    Apr 16, 2010
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    You may be right, and I wish you the best of luck. I hope that someone will help; I would if I could. :)
     
  5. Lundwall_Paul

    Member

    Oct 18, 2011
    220
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    Is the short between power and ground?
    Have you powered it up after cleaning it?
     
  6. MrChips

    Moderator

    Oct 2, 2009
    12,446
    3,361
    Sometimes the history of the patient is important.
    So this was not your laptop that was working.
    You acquired this laptop and probably it was dead. So you opened the laptop and took out the mother board. Then you saw this black gunk and cannot tell where it came from.
    Good luck.
     
  7. tryin2fixit

    Thread Starter New Member

    Sep 30, 2012
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    When i plug the laptop power supply in the led on the supply flashes. There's a separate power board and when i plug the supply into that without it being plugged into the mobo it doesn't flash.

    [​IMG]
     
  8. tryin2fixit

    Thread Starter New Member

    Sep 30, 2012
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    Yes, it was like that when i got it.
    I assume the black gunk was diet rc cola from walmart.
     
  9. PackratKing

    Well-Known Member

    Jul 13, 2008
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    OK.........In any event, your short still lives in the little pushbuttons, that are still polluted with whatever that swill was that you cleaned off.........what was it ? Further cleaning hinges on knowing what you are up against.
    It has fair-to-middlin' odds for recovery, if the gunk did not cause major electrical mis-direction...........I have extensive experience [ not to mention dumb luck ] with resurrecting this kind of thing...........
    shoot back !!
     
  10. tryin2fixit

    Thread Starter New Member

    Sep 30, 2012
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    ok, I'm waiting on a 25 watt soldering iron to arrive. The one i have won't get hot enough to take anything off. It'll come tomorrow or the day after.

    I'm also going to try putting an 18v light bulb and maybe a resistor in series with my power supply for now.
     
  11. PackratKing

    Well-Known Member

    Jul 13, 2008
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    I would not recommend powering it up until you have the board and all possible flooded / polluted components absolutely gleaming ! Then bake it in a 100° F oven for a couple hours, then dust with dry compressed air to remove dry detritus wherever it exists
     
  12. dataman19

    Member

    Dec 26, 2009
    136
    29
    So - have you tried replacing the tactile switches? As already mentioned, one or more could be infected with the omnious black crud...
     
  13. tryin2fixit

    Thread Starter New Member

    Sep 30, 2012
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    I took that button off...shook it up soaked it in alcohol overnight.
    Dried it out for a day. Put it back on. Even after that the switch still didn't look too nice.
    I might have a button on another board i can put on there instead.

    I did try plugging it in to see what would happen. The power supply still just blinks.
    Thanks Patratking...Tomorrow i will try baking it at 100 degrees for an hour.

    I tried hooking up a 120v light in series with the motherboard...the light doesn't light up but the power supply light doesn't blink w/ the light hooked up. Than i tried adding a dimmer switch between them but it didn't light up still.

    I'm really not expecting the baking to work but i'm going to try it.
    So, I'm wondering how can i put steady power to the board without it being bad for the supply? Maybe the light was doing it's job even though it wasn't actually lighting?
     
    Last edited: Oct 5, 2012
  14. PackratKing

    Well-Known Member

    Jul 13, 2008
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    Back up a little...............You said - " I assume the black gunk was diet rc cola from walmart."
    The most effective solvent for soda of any stripe, is good ol' soap and water....1:10 mix, and as little as possible to dissolve the culprit - generous rinse...Blow away excess water w/ dry air -- not the canned variety, a compressor w/ dryer......hence the need for baking when everything is shining.
     
  15. tryin2fixit

    Thread Starter New Member

    Sep 30, 2012
    11
    0
    It didn't work. I cleaned off the area and the button off w/ the soap and water, it wasn't spotless but it was the best it would get. I put it in the oven at 100. It still doesn't work.

    I'm still gonna try to learn how to read the schematic and trace the paths.
    I'll try to figure out what components are bad on it i'm not done with it yet.
     
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