macbook pro M1 a2338 no video on internal display PP3V3_S2 short

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  • sdogs
    Senior Member
    • Feb 2016
    • 84
    • Italy

    #1

    macbook pro M1 a2338 no video on internal display PP3V3_S2 short

    Greetings to the entire forum, I ask you for help because I'm going crazy. A dear friend of mine gave me a macbook pro M1 A2338 that only works with an external screen. With the internal one, no backlight or image. Only the external display is detected from the system settings.
    First I changed the display flat, then I made a backup with time machine and tried a reset in dfu but nothing to do, always the same problem.
    I analyzed the logic board, it shows no sign of liquid or visible damage. I then moved on to examine the logic with the thermal camera and found that the UP701 chip was shorted, also shorting PP3V3_S2.
    I repeat, the macbook worked perfectly with an external display.
    I then proceeded to replace UP701 but not much has changed, now it doesn't heat up anymore but I noticed that PP3V3_S2 is always shorted measuring on diode mode.
    The strange thing is that if I take measurements with the logic on the bench I have a short if I power the PP3V3_S2 measures 3.3v....how is that possible.
    If I inject a few volts on that line it doesn't heat anything.
    I noticed with the thermal camera that the chip on the flat of the fan was heating up a lot, is that normal?
    Now, after replacing the UP701 and resetting the firmware the macbook doesn't work properly, it goes to 20v with low current consumption and the fan after a few moments turns to maximum.....any ideas?
  • sdogs
    Senior Member
    • Feb 2016
    • 84
    • Italy

    #2
    sorry I made a mistake in posting here.....now it's in the right place

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