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MacBook 820-00840 Liquid Damage

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    MacBook 820-00840 Liquid Damage

    820-00840 with liquid damage. System powers on and works with external display but no backlight or image on built in display.

    Damage was concentrated in backlight area of the board, in particular C8476 PPVOUT_S0_LCDBKLT which was completely melted and trace damaged.

    On the bottom of the board I've replaced the following damaged components:

    C8475, C8763, C8460, C8462, C8465, C8468, R8401, C8412, R3893, R3894

    On the top of the board I've replaced:
    C8473, C8474, C8478, C8479

    Wondering if maybe Q8400 is bad, but it looks OK after cleaning.
    Attached Files

    #2
    Re: MacBook 820-00840 Liquid Damage

    Are your 100% sure there is no image? Inspect LCD connectors/cables for any damage (especially between the pins for backlight power rail and eDP AUX line).
    OpenBoardView — https://github.com/OpenBoardView/OpenBoardView

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      #3
      Re: MacBook 820-00840 Liquid Damage

      LCD connectors are clean. I also have another screen I tested it with, nothing. When booted off an external monitor Mac OS does detect the build in display so at least the data lines are OK.

      Comment


        #4
        Re: MacBook 820-00840 Liquid Damage

        clean the infected are with water spill with isopropyl alchool like we always do. then with a microscope check carefully if any track on resistor, chip is ok or gor ripped of after corrotion.

        remove temporanely some component, apply flux and fresh solder on the pads and see if they are ok. solder component back and check the voltage that supply lcd backlight to the screen.

        on the picture there are at least 2 area that need carefully be inspected.
        check very well under scope or big magnifier marked zone for any broken track

        check also component on top left marked in red if it's ok...
        Attached Files

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          #5
          Re: MacBook 820-00840 Liquid Damage

          Also make sure both SMC_LID signals are high.
          OpenBoardView — https://github.com/OpenBoardView/OpenBoardView

          Comment


            #6
            Re: MacBook 820-00840 Liquid Damage

            smc_lid_left measures 3.43v

            smc_lid_right 0v
            soooo....
            Last edited by mgrharry; 09-21-2020, 04:55 PM.

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              #7
              Re: MacBook 820-00840 Liquid Damage

              PPVIN_S0SW_LCDBKLT = .13v with screen connected

              Comment


                #8
                Re: MacBook 820-00840 Liquid Damage

                Q8400 has 13V on pin 4 and 3 so voltage is not being lowered. C8400 has been removed and R8402 and R8401 have been replaced.

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                  #9
                  Re: MacBook 820-00840 Liquid Damage

                  LID_OPEN 3.4v
                  BKLT_EN_R 3.35

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                    #10
                    Re: MacBook 820-00840 Liquid Damage

                    Pp3v3_s0sw_lcd 3.34v

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