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a2289 not booting

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    #1

    a2289 not booting

    Hello ,
    I have this 13' macbookPro board 820-01987 that will not show nothing on the screen. Webcam light is always on and while the battery is connected, no fan spin ( just a half spin in the beginning ) ,cpu get warm .Battery disconnected the fan is spinning normally.
    On the usbC meter I have 20V and is going to max 570mA. With battery connected is drawing up to 2,4A.So battery is charging fine.
    What I did : I replace U8110 ( there was no 0,95V on PPVCCIO_S0_CPU and now it's ok)
    I replace U7710 , here still no voltage on L7702
    There is the required voltage on all the coils except on the L7410 , L7420 and L7702 .
    The resistance to ground on these coils is : L7410 4,3 ohm
    L7420 4,3 ohm
    L7702 22,3 ohm
    I tried DFU mode by connecting the pin2 to pin 1 on SE032 and it worked but it didn't do nothing. When I start the restore option the macbook its drawing current but after a few minutes it's stops drawing any current . No any errors , just stop .
    All voltage rails are presents except PVCCGT_S0_CPU and PPVCCEDRAM_S0_CPU .
    Any help would be appreciated .
    Semaca
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    #2
    What is the voltage to ground of PPBUS_G3H @ F7000 (check both sides of this fuse)?

    Remove all power. Meter in DIODE mode. Red meter probe to ground. Black meter probe to point to test.

    Measure the following points of interest:

    SMBUS_3V3_BATT_SCL ; at the battery connector
    SMBUS_3V3_BATT_SDA

    Post each measurements.

    Comment

      #3
      Thank you for answering .
      PPBUS_G3H @ F7000 on both sides is 12,63V
      MBUS_3V3_BATT_SC .952
      SMBUS_3V3_BATT_SDA .979

      Comment

        #4
        These are good measurements.

        What is the voltage to ground of ALL_SYS_PWRGD_R?

        This signal is used to create the PVCCEDRAMS0_EN_FILT_BUF = ENABLE signal for U7710 on pin # 3.

        Comment

          #5
          ALL_SYS_PWRGD_R it's 1,8V while the board is on. The board is on my bench ,out of the enclosure and it's staying on like 10s more or less. Normally they stay always on but this one once it's reach 560mA it's shutting off .
          When usb Cmeter shows 0mA then All_SYS_PWRGD_R it's dropping to 0 .

          Comment

            #6
            I measured ALL_SYS_PWRGD_R on pin 2 from R7759 witch is missing . ON pin 1 should be PVCCEDRAMS0_EN_FILT_BUF and it was 0 while pin 2 had 1,8V .

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