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820-00239 working without battery, burning D6902, U6903

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  • 820-00239 working without battery, burning D6902, U6903

    Hello,

    820-00239 turns on on charger, no liquid damage, no history.

    Board without battery, unplugged all connectors takes from charger:
    20.03V
    0.622A
    Board with battery doesn't start, turns off if connected while working.

    On thermal camera:
    more heat on U6903 (replaced)
    less on D6902 (replaced)
    U3200 also burns hard

    Power rails:
    PPBUS_G3H - 13.12V
    PPDCIN_G3H - 20.26V
    PP5V_S5 - 5V
    PP3V3_G3H - 3.333V
    PP3V3_S5 - 3.363V

    PPBUS_G3H is SHORTED to ground - 0.00 Om

    thanks in advance.
    Last edited by aplas; 10-03-2019, 12:28 PM.

  • #2
    "PPBUS_G3H - 13.12V (SHORTED - 0.00 Om)"
    Are you joking???
    I bet you checked for short with power applied; do NOT do that ever again.

    If board works without battery, all power rails from PPBUS_G3H untill S0 state are good; including 3V3_G3H, so U6903 was good.
    Try first known good battery.
    Post PPBUS_G3H and 3V3_G3H voltage on battery only (NO charger connected).

    Comment


    • #3
      PPBUS_G3H for short checked with charger disconnected, red probe on ground, black on PPBUS_G3H with D6902 removed (sorry for inaccurate writing).
      two different batteries same symptoms.
      on battery:
      PPBUS_G3H - 11.19V
      3V3_G3H - 2.8V

      Comment


      • #4
        "PPBUS_G3H - 13.12V (SHORTED - 0.00 Om)"
        Then explain us how this possible...

        Is REALLY IMPOSSIBLE to have 0 ohm on a power rail where you are able to get 13V!!!
        If we cannot trust your measurments, we cannot help.

        Apart of that, 3V3_G3H is not good on battery only.
        Post all U6903 voltages for such case.

        Comment


        • #5
          I get 0Ohm to ground of PPBUS_G3H only right after disconnecting the power. If the board is left disconnected for a period of time it shows ~4kOhm.
          See photos attached.

          U6903 on charger:
          1 P3V3G3H_VBST - 8,43V
          2 PPVIN_G3H_P3V3G3H - 19,60V
          3 P3V3G3H_LX - 3,52V
          8 P3V3G3H_BIAS - 4,98V
          9 P3V3G3H_FB - 0,978V
          10 PM_EN_P3V3_G3H - 5,11V
          Last edited by aplas; 10-04-2019, 06:49 AM.

          Comment


          • #6
            Always allow some time (10-20s) before diode mode readings, after power is removed.

            I asked about U6903 voltage on battery only...

            Comment


            • #7
              U6903 on battery:
              1 P3V3G3H_VBST - 8,5V
              2 PPVIN_G3H_P3V3G3H - 10,61V
              3 P3V3G3H_LX - 3,12V
              8 P3V3G3H_BIAS - 4,97V
              9 P3V3G3H_FB - 0,865V
              10 PM_EN_P3V3_G3H - 5,10V

              Comment


              • #8
                What is the exact 3V3_G3H voltage now (at R6915)?

                Comment


                • #9
                  at R6915:
                  PP3V3_G3H - 2.919V
                  PP3V3_G3H_REG_R - 2.931V
                  Attached Files

                  Comment


                  • #10
                    3V3_G3H is adjusted by R6910-13 divider.
                    One of resistors is out of range.
                    You can adjust one, to correct the problem.
                    In your case, need a bit lower R6911+13, or bit higher R6910+12.
                    Last edited by 2informaticos; 10-08-2019, 06:38 AM.

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                    • #11
                      I was able to increase the voltage on PP3V3_G3H only to 2.955V by replacing R6910 to 200kohm resistor. If it resist more, very low voltage is generated and macbook doesn't start from charger.
                      Did I mention that computer turns itself off only after connecting J6951 flex cable. It's working with battery +/- connected.

                      Comment


                      • #12
                        You need to increase, not decrease 3V3_G3H; modify some resistor accordingly.

                        The board works perfectly without J6951 connected?
                        3V3_G3H is then normal voltage?
                        Try known good working battery.

                        Comment

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