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Macbook Pro 820-3662 No Chime, No Display

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    #1

    Macbook Pro 820-3662 No Chime, No Display

    Hi there,
    New to component level repair so your patience would be hugely appreciated!
    I'm working on a water damaged Macbook Pro 820-3662.

    Firstly, I get no fan spin and no S4_PWR_EN without the battery plugged in, however this comes on with the battery and adaptor.

    With battery and adaptor, it has a light on the charger and fan spin but I get no chime and no display.

    EDP_IG_PANEL_PWR is currently 0V but PP5V_S4 is 5V, thats the extent of my troubleshooting for display related stuff.

    The CPU gets warm so something is going on in there.

    Would appreciate any help and guidance you guys can give me!
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    #2
    Re: Macbook Pro 820-3662 No Chime, No Display

    If it doesn't start on AC adapter only, the AC adapter is not compatible with the machine. Make sure you use known good genuine Apple 85W Magsafe2 (no Magsafe1 to Magsafe2 adapter).

    Measure voltage on CPU VCore.
    Try PRAM reset.

    What's the history of the board?
    Last edited by piernov; 05-20-2019, 09:42 AM.
    OpenBoardView — https://github.com/OpenBoardView/OpenBoardView

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      #3
      Re: Macbook Pro 820-3662 No Chime, No Display

      Thanks for the reply, the AC adaptor is a genuine Apple Magsafe 2, I use it on my personal laptop so I know it's good! I do get a light on the charger with just the adaptor, just no fan spin. I also get some power rails up e.g. PP5V_S5, PP3v3_S5

      I've tried a PRAM reset, with no results, exactly the same.

      Could you give a bit of guidance on measuring CPU VCore? Had a look on my boardview and can't find it listed on there.

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        #4
        Re: Macbook Pro 820-3662 No Chime, No Display

        It is an 85W one right? It won't work with 45W or 60W.
        CPU VCore is called PPVCC_S0_CPU on this board.
        OpenBoardView — https://github.com/OpenBoardView/OpenBoardView

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          #5
          Re: Macbook Pro 820-3662 No Chime, No Display

          Thanks, my charger is 45W so that explains it!

          Thanks for the help with CPU VCore, it is reading 1.76V.

          Comment

            #6
            Re: Macbook Pro 820-3662 No Chime, No Display

            85W charger arrived, the problem persists, light on the charger, fans spin but no display and no chime. CPU Vcore is still at 1.7ishV.

            I've tested all 5v, 3v and 1v rails listed under power aliases and all are present.

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