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Dead LA-F481P laptop motherboard: thicking noise

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    #1

    Dead LA-F481P laptop motherboard: thicking noise

    Hello to everyone! I have a Lenovo laptop with a broken motherboard. It doesn't show any sign of life, no fan, no leds, no whatever you may think of. The only sign is a constant thicking noise coming from a zone of the motherboard which I have taken a photo on both sides. I have touched all the components looking for an overheated one indicating some kind of power drain but nothing unfortunately, too easy!
    I tend to believe about a power stage issue otherwise it should at least charge the battery, shouldn't it? What do you think? Any advice is precious to me so thanks in advance to everyone!
    Attached Files
    Last edited by SMDFlea; 10-15-2021, 07:05 AM. Reason: LA-F481P
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    #2
    Re: Dead laptop motherboard: thicking noise

    i see at least 2 blown ic chips ..dont power it on again until fixed or things might get worse
    Attached Files
    Last edited by petehall347; 10-07-2021, 12:44 PM.

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      #3
      Re: Dead laptop motherboard: thicking noise

      I thank you! I need to check the board more thoroughly then scour a service manual for it otherwise I wouldn't be able to find the right replacements... My soldering skills with SMD components remain the biggest problem unfortunately! Hot air or what? Are there some tutorials on Youtube or else on how to deal with those particular packagings? I could just go to a mobile phone repair shop and they should handle the repair more than well but how much for it without any guarantee for a successful repair?
      Last edited by guybrushthreepwood; 10-14-2021, 12:37 PM.

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        #4
        Re: Dead laptop motherboard: thicking noise

        Hello again. I've found the schematics (LA-F481P) here but they don't contain a drawing of the whole board so this is quite hard... I've taken a look at the board itself and determined that the faulty components found by petehall347 should be PQ1652 (a EMZB08P03V mosfet according to the schematics) and PU1101 (a AOZ5048QI 35A QFN24 DC/DC converter) but I'm not absolutely certain about the second one while the former makes absolutely sense.
        Still on the schematics it is adviced to replace some other stuff

        1. Change PU1101,PU1102,PU1151 from CSD97396Q4M to AOZ5048QI
        2. Change PC1101,PC1112,PC1151 from 1U_0603_10V6K to 4.7U_0603_10V6K

        when replacing PU1101. I'm quite clueless...
        Last edited by guybrushthreepwood; 10-15-2021, 06:20 AM.

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          #5
          Re: Dead LA-F481P laptop motherboard: thicking noise

          Did you find the source or cause of that thinking sound or is that normal?

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