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Asus FX705DT eDP and HDMI output issue

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    #1

    Asus FX705DT eDP and HDMI output issue

    Hi

    I have an Asus FX705DT that had waterdamage....a lot

    I have managed to make the motherboard look like working but i stil have some issues and maybe someone can point me in the right direction.

    The laptop has a destroyed keyboard and the display is dead but i have managed to make the board start up and work "normal"...i have no short,power rails are looking good,hdd/ssd activity and so on.

    The problem is that there is no HDMI output,only sometimes makes the tv/monitor go black screen for a brief moment,and on the internal eDP no signal to any display i have tested so far.I don't have a similar 17.3 60hz display but i have tested a bunch of 15.6 and 13.3 slim and normal HD and FHD....no signal or at least backlight.I have power on the display connector tho.

    As i have read on other forums and here aswel,the internal eDP is connected to the CPU and the HDMI is connected to the dedicated GPU.When i start the laptop it show image only on the internal display and after drivers are installed it starts the external one.

    Is there any way to edit the expected EDID data in bios or the mod it in such a way that it outputs image on the HDMI from the begining ?!I want to use the board with an external display for the rest of it's life...

    Or fi anyone tested,is there any way that an eDP to DisplayPort adaptor will work in this case ? I was thinking about rerouting the eDP to hdmi port as it only requires a few wires and removing a few components

    Thanks
    Tags: None
    #2
    Re: Asus FX705DT eDP and HDMI output issue

    ok,i tried to reroute the signal but still no image.I have managed to put an ssd with windows on it and acces to internet and after a while it automaticaly installed the video driver and got an image on hdmi.tested out the laptop and everything seems ok except the iGPU that states it can't start.i suppose that happens because it can't "detect" any internal display.

    if anyone managed ever to convince the iGPU to accept a different display than the one installed from the factory,point me to an explanation so i could figure a way to make a fix on this one...

    thanks

    Comment

      #3
      Re: Asus FX705DT eDP and HDMI output issue

      Hi, you can try to simulate the lid closed, this way it will redirect the signal to the HDMI.

      Comment

        #4
        Re: Asus FX705DT eDP and HDMI output issue

        Tried that...won't start.Probably the algorithm for power on includes lid checking.Also tried to put a magnet on the hall sensor after powering on but still same result.Keeping the magnet on tha sensor,after uefi boot will trigger the sleep function....

        I want to turn this board in a "mini pc" as it's not worth it to replace all the external defective parts...keyboard,display,case,trackpad and battery...

        I think this is the first time i find a laptop that will not accept a lower size of display iven tho it has similar characteristics or iven better.

        Comment

          #5
          Re: Asus FX705DT eDP and HDMI output issue

          You need to change the action for "Lid close action". Go to Power Options, Advanced settings, Power buttons and lid, Lid close action, Plugged in: and select Do nothing.

          Comment

            #6
            Re: Asus FX705DT eDP and HDMI output issue

            Found the culprit after buying a new display and still not working....

            Apparently a mosfet was acting bad and was lowering the output voltage for the display power supply.It seemed odd that on lower size displays sometimes i would get some lines and dots without backlight but the LED power supply was ok.The problem was on the LCD_VCC as it was varrying around 2.8-2.95 and was just beneath the treshold for working.I found out that it needed at least 3v to power on and 3v3 to work normaly.I did not think that such a small difference would make the case of not working at all.

            The LCD_VCC circuit has a "power switch" made with an ic that enables,disables and prevents shortcircuits from propagating on the 3v3 rail in case a bad display is connected.The ic itself contains a mosfet that apparently sometimes goes bad.

            Good to check for others in case they encounter situations like this.

            Cheers everyone!

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