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Macbook air a1932 not working with audio board connected

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    #1

    Macbook air a1932 not working with audio board connected

    Hi,

    I have macbook air a1932 2018 and it has water damage. Audio connector on motherboard was burned on PPBUS_G3H signal. Without this audio board laptop is working perfectly fine, but of course without sound and touch ID. I changed burned connector, flex cable and audio board. But connecting this all, Mac is not starting, nothing on thermal camera... Do you know what other can be damaged on this signal what can cause this behaviour? Nothing on motherboard looks burned...
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    #2
    Re: Macbook air a1932 not working with audio board connected

    What is the 820-xxxx logic board number ?

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      #3
      Re: Macbook air a1932 not working with audio board connected

      820-g1521-a

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        #4
        Re: Macbook air a1932 not working with audio board connected

        1) 820-01521 ?

        2) See attached. Remove all power. Remove the audio board and check the resistance to ground of each of the I2C lines linked to the audio circuits.

        Use the lowest resistance scale on your meter. If you see '1' then switch to the next higher scale on your meter till you have a reading.

        Post the measurement & scale used on your meter.

        3) Still with no power, attach the audio board. Then check the resistance to ground again of the same I2C lines.

        Perhaps the I2C lines are being strapped by the audio board and causing the host logic board to enter a blocked state and preventing a proper boot.
        Attached Files

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          #5
          Re: Macbook air a1932 not working with audio board connected

          1. yes, sorry about that
          2. I started to check them and all of them was about 12.5kohm, but it gives me idea to check resistance of PPBUS_G3H, what turns out is shorted to GND... It is now working with another audio board (old one, it turns out that new one has shorted capacitor...) Now I don't have sound in right speaker, but probably it is because on wrongly ironed connector... I can see that with board all of I2C signals has 11.5kohm but R_SDA not, so I assume there is a problem.Thanks for your help

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            #6
            Re: Macbook air a1932 not working with audio board connected

            Very good. It should be fairly quick to locate the shorted cap - maybe there are only a few on this audio board and you can remove one at a time to locate the bad one.

            Use flux to clean up the connector pins and then IPA (alcohol) to remove the excess flux. Looks like you are close to fixing this case.

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