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820-00928 NO water damage, 20V, No fan, no chime, no image, no boot

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  • 820-00928 NO water damage, 20V, No fan, no chime, no image, no boot

    Hi there,

    No signs of water damage.
    Magsafe charger switches from 5V to 20V.
    All main coils (and there are many on this board) - 0V, except for L7660 - 3.31V.
    No pulse on ON/OFF button press.
    SMC bypass - same. Though I am not sure if SMC bypass procedure is the same as on previous generation board: HOLD the ON/OFF then connect Magsafe, wait 5 secs and release and press ON/OFF?
    Not much experience with this board yet. Please advice how to proceed.

    THanks!

  • #2
    There should be some fault history.

    Do you get PM_BATLOW_L and PM_SLP_SUS_L?
    Also post PM_DSW_PWRGD, PM_RSMRST_L, PM_PWRBTN_L.

    Comment


    • #3
      Called the customer. He confessed that it had previous liquid spill on keyboard over a year ago and keyboard was replaced. Worked fine ever since then until just recently. The battery ran out and after that does not go on.
      It should turn on with battery disconnected, right?
      PM_BATLOW_L - 3.28V
      PM_SLP_SUS_L - 3.31V
      PM_DSW_PWRGD - 3.41V
      PM_RSMRST_L - 3.29V
      PM_PWRBTN_L - 3.31V

      Comment


      • #4
        Do you have steady 3V at SMC_ONOFF_L?
        If not, disconnect J4900 and check again.

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        • #5
          Do you have steady 3V at SMC_ONOFF_L - YES

          Comment


          • #6
            Trigger SMC_ONOFF_L and check for drop pulse at PM_PWRBTN_L.

            Comment


            • #7
              Trigger SMC_ONOFF_L and check for drop pulse at PM_PWRBTN_L - YES 3-0-3

              Comment


              • #8
                Now check for pulse at all PM_SLP_Sx_L signals.

                Comment


                • #9
                  Pm_slp_s5_l - 0v
                  pm_slp_s4_l - 0v
                  pm_slp_s3_l - 0v
                  pm_slp_s0_l - 0v

                  Comment


                  • #10
                    Did you check for pulse at same time when SMC_ONOFF_L was triggered?
                    If nothing, looks like PCH/CPU issue.

                    Please do NOT repeat my questions, just post your answer.
                    Especially when is one question per post only...
                    Last edited by 2informaticos; 02-17-2020, 09:40 AM.

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                    • #11
                      Yes.
                      Thanks for your help!

                      Comment


                      • #12
                        Check if you have 3V3_SUS and 1V8_SUS.

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