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Asus X556UQ-XX453T not turning on, not charging

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    Asus X556UQ-XX453T not turning on, not charging

    Hi guys

    I got this laptop some time ago, but started to check it out just now.
    Friend that gave it to me says that one day, after turning it of the next day would not start. He sent it to some repair shop but they didn't manage to fix it. But they did manage to tear few traces for bios ic. That is fixed now, but i am not sure that the bios that is programmed to ic is the right one for this laptop. Found few dumps here on the site but with neither of them laptop starts.
    Laptop is not starting, not charging battery. Plugged in LED is on, but charging LED does not come on. As soon as I plug it in it starts to draw around 220mA. My main question is could it be that IT8995 is corrupted and because of that is not starting even to charge the battery? Or is BQ24780s completely independent of EC and it should start to charge battery as soon as plugged in?
    3.3V, 5V are present, 1.2 for ram, 0.8V for 940MX.
    I was not able to find any obvious shorts.

    Can BIOS or EC cause Laptop to "turn on" and get all votages except VCCGT without even pressing power button (which btw tested ok)?

    Attached photo of mainboard with some voltages (written with black marker )

    Thanks
    Attached Files

    #2
    Re: Asus X556UQ-XX453T not turning on, not charging

    First try to post the bios dump - in bios section _ , maybe it needs clean me.
    Did you have his schematics ou boarderview !
    Last edited by lapfix; 05-25-2020, 08:40 AM.

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      #3
      Re: Asus X556UQ-XX453T not turning on, not charging

      Yes, laptop can turn on without pressing power button if cmos battery is not connected(Not on all platforms) BQ24780 or any other charging ic works with kbc and cannot charge without a functional kbc (SDA/SCL/ACDET,ACOK are few signals which needs to talk with kbc. So BQ24780 cannot charge independently. Hope that clears your confusion.

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        #4
        Re: Asus X556UQ-XX453T not turning on, not charging

        After finding the correct bios also check if the ec receives the right voltage

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          #5
          Re: Asus X556UQ-XX453T not turning on, not charging

          Flashed new bios dump that was posted in Bios section, but the laptop is not starting. Will try to investigate voltages on IT8995, although 3.3V for EC is present.
          Board view attached.

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