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Asus Laptop GL702VS black screen power LED on

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    Asus Laptop GL702VS black screen power LED on

    Hi,
    I am fighting with this laptop and I am suspecting of the GPU, but it would be great to know your opinion.
    The laptop originally does show black screen (no back light) but the power button LED turn on and off when pressing it.
    I did the next trouble shooting with no changes
    - Disconnected the battery and try just with the power supply
    - Disconnected all power sources, even the CMOS battery and held the power button for 40sec.
    - Disconnected hardrives
    - Deplaced the RAM
    - Disconnected the Wifi module
    - I connected a external monitor to the HDMI port
    NO changes here.

    Troubleshooting that did make changes:
    - The motherboard was taken out from the computer. Keeping the heatsinc.
    - When the CMOS battery is disconnected it seems to turn on as soon as you connect the power supply.
    - The laptop monitor is disconnected
    - I connected a HDMI monitor
    - After a while, the monitor showed image, like a glitchy BIOS (uploading picture)
    - After some tries removing the external power and powering it again, it start working "fine"
    - Looks like being warmer it powers on faster and the image ends being fine.
    - I used the occasion to reload the BIOS (having to connect the battery for that).
    - At some point it looked like it was working even if it was no so hot.
    - I mounted the motherboard back, connected the laptop monitor together with the HDMI monitor and again I got nothing (black screen), but I plugged a USB and the light was blinking.
    - As soon as the laptop monitor is connected nothing happens.

    The resistance to the GPU power line (if I got the right one as I don't have the schematic) to ground is 0.5 Ohms.

    When I took off the heatsinc to inspect it I noticed the previous person put a lot of thermal paste. I cleaned it and put just enough, but no changes.

    It completely looks like a dead GPU, but the fact that the laptop monitor seems not to work, makes me think that something else might be wrong.

    Ah... one of the times I let the computer off and the battery charging (it was 40%). After 1h or so I came back, disconnected all power sources, and I was measuring some MOSFETs. Then I connected everything back (except the laptop monitor, external monitor connected) I press the button and it powered on right away with perfect image. The computer was cold, because even the fans were not spinning. That also is giving me some hope. Then I connected the laptop monitor and everything went back to what it was before, black screen, and glitcht externam monitor when I disconnected the laptop monitor.

    The voltage that get to the LVDS is 20V

    Any ideas are appreciated. Thanks!!
    Attached Files
    Last edited by samolo75; 03-31-2021, 03:23 PM.

    #2
    Re: Asus Laptop GL702VS black screen power LED on

    More test
    Looks like it works when cold with the external monitor. I just left it for 1h charging and the screes started just fine (external monitor), then I rebooted and it went bad again.

    NVVDD = 0.7V
    VCCCORE = 0.9V

    And attached the screen working fine.
    Attached Files

    Comment


      #3
      Re: Asus Laptop GL702VS black screen power LED on

      Could it be that one of the Mosfets of the GPU is shorted to ground? so still can power up ok sometimes?
      I did manage to have the external monitor working a couple of times. I heated up the GPU and then it worked for like an hour (turning it on and off), even letting it cool for quite a while. But then I mounted the board on the case and it stopped working.
      The resistance on the NVVDD to ground is 0.5 Ohms, which is pretty low, but I understood it could be that low.

      The mosfets are dual N Mosfets 5018SG
      The resistance between P_NVVDD_LX1_30 and P_NVVDD_LX1_L_30 is 0.3 Ohms. Which I am not sure if it normal... it is the same with LX1-LX4.

      Using a thermal camera you can see that one of the mosfets gets a bit hotter than the rest, but it is like 1 C degree.
      Last edited by samolo75; 04-01-2021, 01:28 PM.

      Comment


        #4
        Re: Asus Laptop GL702VS black screen power LED on

        With Nvidia 1000-series and newer, resistance to ground lower than 1 ohm on GPU VCore is normal. Probably just a dying GPU.
        OpenBoardView — https://github.com/OpenBoardView/OpenBoardView

        Comment


          #5
          Re: Asus Laptop GL702VS black screen power LED on

          Hi all,
          There have been some changes.
          One of the times it was working fine I left it for a while and then it suddenly the computer when off (the fans were installed). I unplugged it and plugged it back but nothing.
          With the charger, input voltage on the connector was on but it would go nowhere else.
          Then a found three components that died and where shorted. The charge controller, one of the mosfets feeding the graphics chip and another mosfet generating the 5VSB. I replaced them and all voltages where back to normal, plugging the charger the computer would start. The difference is that now I would not get any image at all at any point. And plugging a USB drive to a USB port would not show signs of live. I thought that probably the Graphics finally dies completely. The CPU and the GPU get hot, so they seem to do something.
          Since this is a learning process, I thought I would try reprogramming the BIOS.
          I made a backup of the "original BIOS" and got some dump BIOS files online.
          I reprogrammed the BIOS (both BIOS and EC) and now the computer starts and shows a black image, (before there would not be video output at all) and the USB drive blinks, like it is doing something. And now connecting the internal monitor of the laptop the backlight comes on but with black image, before it would do nothing. Even when it was glitchy the internal monitor would not turn on the back light.
          I am uploading here the 4 BIOS files I got. Dump files BIOS+EC and the original one. Please, some expert could have a look to them and tell me if I can just flash the dump files? Or there is something it need to be done to fir the current motherboard. It is my first time playing with BIOS files.
          Thanks in advance!!
          Last edited by SMDFlea; 04-17-2021, 08:51 AM.

          Comment


            #6
            Re: Asus Laptop GL702VS black screen power LED on

            I am not sure if it is important. But here it is the BIOS I flash earlier downloaded from the ASUS website. Flashed in the regular way with the computer "working".
            Last edited by SMDFlea; 04-17-2021, 08:52 AM.

            Comment


              #7
              Re: Asus Laptop GL702VS black screen power LED on

              Originally posted by samolo75 View Post
              I am not sure if it is important. But here it is the BIOS I flash earlier downloaded from the ASUS website. Flashed in the regular way with the computer "working".
              Post your bios in the "Bios Requests ONLY!" section - https://www.badcaps.net/forum/forumdisplay.php?f=40
              All donations to badcaps are welcome, click on this link to donate. Thanks to all supporters

              Comment


                #8
                Re: Asus Laptop GL702VS black screen power LED on

                Thanks @SMDFlea I did post in the Bios Request section.
                Regards

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