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820 00045, don't turn ON

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  • 820 00045, don't turn ON

    Hey guys,

    working on 820 00045, No one touch on this board before me and don't have any corrosion! the customer said that he stopped working suddenly!

    All "G3Hot" (Always-Present) Rails are present and stable until PP5V_S4.

    From PP5V_S4 to PP1V05_S0 are pulsing!

    For example PP5V_S4 are pulsing 5V and off - 5v and off! Like to PP1V05_S0 1.1V and off repeatedly!

    Already replace U4700 for a new one and no changes!

    Any idea to this one?? already searched on forum but i can't find any problem related to this!


  • #2
    Check for shorts across all rails. If no shorts, this one may not be good news. CPUs dropping like flies on these things.


    • #3
      VCORE pulsing too?
      CPU is the first suspect on these boards...


      • #4
        Yeah same if VCore pulses you can always try a new BIOS but at least the last 30 12” MacBooks I’ve had have all had bad CPUs


        • #5
          Hey guys,

          After Easter holidays this motherboard don't have more rails pulsing! All rails even Vcore are constant! I can feel the board warm like a working board!

          Already heat the processor a bit, but don't changes! I think the CPU it's damage!

          It's possible on this mode even with damaged processors to recover the information on internal SSD?

          Other question its possible to reprogram the bios on this models with TL866 for example ?


          • #6
            Yeah dead CPU 100% RIP. I am not sure on data recovery I am curious as well! BIOS can be programmed but it is BGA, so you have to remove it, reball, solder to programmer, remove, reball, and resolder without breaking it...better to use something like Medusa to access the BIOS through JTAG connector.


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