Asus g751jy no voltage on 3V3main and aon net

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  • myth77
    Badcaps Veteran
    • Feb 2017
    • 380
    • Croatia

    #1

    Asus g751jy no voltage on 3V3main and aon net

    Hello to all, here is the situation....the laptop is turning on, no picture,has no voltage on 3v3 main and 3v3 aon net...i look at the boardview (attached) and found that voltage should come from 12vsus net, but for some reason it is not. First i found that the ec chip 25x40clsnig is not receiving any power, the voltage reading was zero or 0,1 v on aon net.
    I was finally able to find area where the power problem is but i dont understand why and which part is responsible...please help

    So first picture, this is ec chip and nowhere there is voltage relating ground, on aon net 0.09v.

    (Image hosting links dead)

    I was searching through the boardview, checking how 3v3 main and aon nets are connected to the rest of the board and on the next picture i found that somewhere here is the problem. That resistor r7124 is not transfering the voltage from +12vsus net on DGPU power main.

    I was not sure about that so i borrow exactly the same laptop from my friend and i was right. His readings from his motherboard are ok and shown on the next picture.

    (Image hosting links dead)

    I am not sure now what is going on. I checked resistence of that resistor (while on board) and it is reading 100k ohm. can anybody look at the boardview and picture please and suggest what to do next.
    Thank you all!
    Attached Files
    Last edited by SMDFlea; 12-27-2019, 06:20 AM. Reason: Image hosting links dead
  • piernov
    Super Moderator
    • Jan 2016
    • 4435
    • France

    #2
    Re: Asus g751jy no voltage on 3V3main and aon net

    The stuff you're looking at is for the dedicated GPU. You'll need the main BIOS to run for the GPU to be turned on (if I'm not mistaken).
    Also U9402 is the VGA BIOS.

    Do you have +VCORE and CPU_RST#?
    OpenBoardView — https://github.com/OpenBoardView/OpenBoardView

    Comment

    • myth77
      Badcaps Veteran
      • Feb 2017
      • 380
      • Croatia

      #3
      Re: Asus g751jy no voltage on 3V3main and aon net

      on +vcore i have 1.79v, and arround 23 ohms relating ground (while not working)
      on cpu_rst i have 1.09v

      Main BIOS i already tried to reprogram with some bios dump i found on the internet but its the same thing, no power to vga bios.

      Comment

      • myth77
        Badcaps Veteran
        • Feb 2017
        • 380
        • Croatia

        #4
        Re: Asus g751jy no voltage on 3V3main and aon net

        Piernov?... anybody?

        Comment

        • zoltor
          Member
          • Nov 2016
          • 30
          • Казахстан

          #5
          Re: Asus g751jy no voltage on 3V3main and aon net

          Good day, in my case it turned out to be faulty FERRITE BEAD L7133, located near the gpu flash - U9402.

          Comment

          • zoltor
            Member
            • Nov 2016
            • 30
            • Казахстан

            #6
            Re: Asus g751jy no voltage on 3V3main and aon net

            EDIT: Image hosting links dead
            Last edited by SMDFlea; 12-27-2019, 06:19 AM. Reason: Image hosting links dead

            Comment

            • zoltor
              Member
              • Nov 2016
              • 30
              • Казахстан

              #7
              Re: Asus g751jy no voltage on 3V3main and aon net

              https://drive.google.com/drive/folde...vZ?usp=sharing

              Comment

              • degutji
                Senior Member
                • Dec 2012
                • 173
                • Indonesia

                #8
                Re: Asus g751jy no voltage on 3V3main and aon net

                link is dead , can u upload again ? Thx

                Comment

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