macbook pro M1 a2338 no video on internal display PP3V3_S2 short

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  • sdogs
    Senior Member
    • Feb 2016
    • 86
    • 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?
  • mon2
    Badcaps Legend
    • Dec 2019
    • 13927
    • Canada

    #2
    High fan spin is linked to missing the sensors in your trackpad. Remove and inspect the contacts of your trackpad cable.

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    • sdogs
      Senior Member
      • Feb 2016
      • 86
      • Italy

      #3
      The fan was a bad battery cable, but otherwise I managed to get Logic to restart, so the problem is related to the WiFi card. I removed all the capacitors around the chip, hoping one of them was broken. In reality, it's PP3V3_S2_WLBT_INS that's shorted. I read this article a bit:
      https://logi.wiki/index.php/M1_MacBo...I_Module_death
      and I'm in exactly the same situation. I was thinking of isolating all the PP3V3_S2_WLBT_INS lines and re-soldering the chip, but I don't know if that makes sense.
      I was thinking, and I think it's crazy, about installing a WiFi dongle inside the Mac, but I'm afraid there's no service USB line. I'm looking at the wiring diagram, but I don't think there is one, and I don't know if it would be a good idea.
      Obviously, even installing a donor chip doesn't seem to be usable.

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