820-01958 chime, blank display and restart

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  • kingskie
    Badcaps Veteran
    • Oct 2014
    • 249
    • indonesia
    #1

    820-01958 chime, blank display and restart

    Hi all,

    i have macbook air A2179 820-01958 that some water damage around:
    - CC714 and CC715 (PP5V_G3S)
    - C6523 (PPVOUT_S0_KBDBKLT_R)
    - F3000 (PPDCIN_G3H and PPHV_INT_X_G3H)

    after clean all those components. i tried to turn it on bust have blank display and always restart (based on chimes)

    here are the measurements:

    - PPBUS_G3H = 12.58V
    - PPBUS_HS_CPU = 12.58V
    - PPDCIN_G3H = 19.98V
    - PP5V_G3S = 5V
    - PP5V_S5_LDO = 5V
    - PP3V3_G3H_RTC = 3.271V
    - PP3V3_G3H = 3.271V
    - PP1V8_G3S = 1.795V
    - PPVCC_S0_CPU = 1.6V
    - PP1V1_S3 = 1.095V
    - PP0V6_S3 = 1.01V

    N.B CPU is very hot

    what could be wrong?
    any help would be appreciated.

    thanks before
    Tags: None
    • mon2
      Badcaps Legend
      • Dec 2019
      • 13944
      • Canada
      #2
      Re: 820-01958 chime, blank display and restart

      hi.

      1) do not power on as PP0V6_S3 = 1.01V is incorrect and could cause damage. This rail should be 0V6.

      2) See attached. Inspect the parts in the red box. Each value should be correct to properly allow for the buck regulator to regulate to 0V6. Based on the measured value, the FB resistor(s) are not the proper value.
      Attached Files

        Comment

        • kingskie
          Badcaps Veteran
          • Oct 2014
          • 249
          • indonesia
          #3
          Re: 820-01958 chime, blank display and restart

          Originally posted by mon2
          hi.

          1) do not power on as PP0V6_S3 = 1.01V is incorrect and could cause damage. This rail should be 0V6.

          2) See attached. Inspect the parts in the red box. Each value should be correct to properly allow for the buck regulator to regulate to 0V6. Based on the measured value, the FB resistor(s) are not the proper value.
          i checked value for:
          R8150 9.8ohm
          R8151 90.8ohm
          R8152 2K ohm

          so i changed R8152 but the value still 2K ohm...if P0V6_S3_FB is shorted that means the value for R8151 shouldnt be normal right?

            Comment

            • kingskie
              Badcaps Veteran
              • Oct 2014
              • 249
              • indonesia
              #4
              Re: 820-01958 chime, blank display and restart

              i just found out that PP1V1_S3 is shorted to ground

                Comment

                • M4n0l0307
                  Senior Member
                  • Nov 2020
                  • 161
                  • Colombia
                  #5
                  Re: 820-01958 chime, blank display and restart

                  Originally posted by mon2
                  hi.

                  1) do not power on as PP0V6_S3 = 1.01V is incorrect and could cause damage. This rail should be 0V6.

                  2) See attached. Inspect the parts in the red box. Each value should be correct to properly allow for the buck regulator to regulate to 0V6. Based on the measured value, the FB resistor(s) are not the proper value.
                  Thank you friend !

                    Comment

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