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Asus X540UP Turns on automatically but not working

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    Asus X540UP Turns on automatically but not working

    Greetings!

    I'm trying to fix this Asus X540UP motherboard and I can't locate the problem. Initially, the board went dead. I assumed it could be some caps or mosfets. But then when I checked it under a thermal cam the CPU is warming up around 35 to 40 celcius. The 19v is present at locations specified by the boardview. 3.3, 3.2, 1.2, 5 & 12 is present. Only the GPU is dead cold. The board is divided into 3 sections. The middle section where the CPU and GPU are located show shorted power supplies (mosfets, inductors, big round caps). I reflowed both GPU & CPU thinking that they are what's causing the short. the reading improved compared to when I measured the components using diode mode, from 0.0004 to 0.0012 (at least). But the condition is still the same, board automatically turns on, power led lights up, CPU warms to 30-40C, GPU dead. It's just odd for the board to automatically turn on when plugged in. Battery (somehow) charges but drains immediately. I'm stuck as to which component is causing the short in the CPU/GPU section. Played with the switch but the problem is not there. 1.2v is present around the RAM. I will appreciate any suggestions. Thank you for your time.

    #2
    Re: Asus X540UP Turns on automatically but not working

    Why would you reflow CPU & GPU without testing other stuff first? Reflowing is usually the last resort since it can cause more harm than good if not done properly. Often many boards that could have been fixed become unfixable because of that.

    In your case, measure resistance to ground on all coils and report back. Try flashing your BIOS with a known good one.

    Comment


      #3
      Re: Asus X540UP Turns on automatically but not working

      https://www.badcaps.net/forum/showpo...02&postcount=2
      OpenBoardView — https://github.com/OpenBoardView/OpenBoardView

      Comment


        #4
        Re: Asus X540UP Turns on automatically but not working

        Originally posted by Spider1211 View Post
        Why would you reflow CPU & GPU without testing other stuff first? Reflowing is usually the last resort since it can cause more harm than good if not done properly. Often many boards that could have been fixed become unfixable because of that.

        In your case, measure resistance to ground on all coils and report back. Try flashing your BIOS with a known good one.
        cant agree more than 100%

        Comment


          #5
          Re: Asus X540UP Turns on automatically but not working

          I really appreciate all your comments. Thank you Spider1211 for the insight. I'll measure them (coils) asap and give you the feedback. Thanks piernov for the resources. mcplslg123 thanks for the feedback.

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            #6
            Re: Asus X540UP Turns on automatically but not working

            tested resistance to ground. please see attached snap shot of the board with written values. thanks!
            Attached Files

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              #7
              Re: Asus X540UP Turns on automatically but not working

              Resistance seems OK. Hoping you did not damage the BGA, try cleaning your BIOS, if that dsnt work, try flashing your BIOS with a known good one.

              You can request clean bios in the BIOS section if you don't know how to do it yourself and someone will help you.

              Comment


                #8
                Re: Asus X540UP Turns on automatically but not working

                Thanks so much for pointing me where I can start Spider1211! The only choice I think I have is to change the BIOS. The laptop does turn on (power led automatically lights up when plugged) but nothing happens. Will go the the BIOS section just like you said. Will update asap.

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                  #9
                  Re: Asus X540UP Turns on automatically but not working

                  It would be better if you can write voltage on those coils also.

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