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A1465 820-3435-B Fan spins on and off

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    #1

    A1465 820-3435-B Fan spins on and off

    Hi,

    So I'm quite new to board level Macbook repairs, done a few backlight fixes however I'm tackling my first "Does not boot" issue, kind of feel like I've jumped in the deep end with this one.

    This board has no real signs of liquid damage apart from a few brown test points.
    All that happens is the fan will spin for about 1 second, and then stop and will continue to cycle like this indefinitely.

    Here are all my current readings:

    PPBUS_G3H - 8.6v
    PPBUS_S5_HS_COMPUTING_ISNS - 8.6v
    PPBUS_S5_HS_OTHER_ISNS - 8.6v
    PPDCIN_G3H_ISOL - 14v
    PPDCIN_G3H - 14v
    PP3V42_G3H - 3.4v
    PPVRTC_G3H - 3.3v
    PP5V_S5 - 5v
    PP5V_S4RS3 - Cycles between 0v-5v every 2 seconds.
    PP5V_S0 - Cycles between 0v-5v every 2 seconds
    PP3V3_S5 - 3.3v
    PP3V3_S4 - Cycles between 2.6v-3.3v every 2 seconds
    PP3V3_SUS - 3.3v
    PP3V3_S3 - Cycles between 0v-3.3v every 2 seconds
    PP3V3_S0 - Cycles between 0v-3.3v every 2 seconds
    PP3V3_S4SW_SNS - Cycles between 0v-3.3v every 2 seconds
    PP3V3_S0SW_SSD - Cycles between 0v-3.3v every 2 seconds
    PP3V3_S4_TBTAPWR - Cycles between 2.6v-3.3v every 2 seconds
    PP1V8_S3 - Cycles between 0v-1.7v every 2 seconds
    PP1V2_S3 - Cycles between 0v-1.2v every 2 seconds
    PP1V05_SUS - 1v
    PP1V5_S0 - Cycles between 0v-1.5v every 2 seconds
    PP0V6_S0_DDRVTT - Cycles between 0v-0.6v every 2 seconds
    PP1V05_S0 - Cycles between 0v-1v every 2 seconds
    PP1V05_S0SW_PCH_HSIO - Cycles between 0v-1v every 2 seconds
    PM_SLP_S5_L - Cycles between 0v-3.3v every 2 seconds
    PM_SLP_S4_L - Cycles between 0v-3.3v every 2 seconds
    PM_SLP_S3_L - Cycles between 0v-3.3v every 2 seconds
    PM_SLP_S0_L - Cycles between 0v-3.3v every 2 seconds

    I have checked U6100 for corrosion/broken traces but all reading ok, I can't seem to find any shorts.

    ALL_SYS_PWRGD is also pulsing.

    I'm not sure where to go from here.
    Does anyone have any suggestions as to what to try next?
    All help will be appreciated

    Thanks
    Tags: None
    #2
    Re: A1465 820-3435-B Fan spins on and off

    did you check J6100 area?
    check that connector under the microscope... i suggest to remove it as it's LPC+SPI Connector and it't not used by any connection inside the laptop...

    Comment

      #3
      Re: A1465 820-3435-B Fan spins on and off

      Thanks for your reply,

      I have checked the J6100 for corrosion however no signs. I will take it off regardless as soon as I can as I see on the schematic there is a lot of TP's under it?

      Also after posting, I was checking everything around the U7100, no corrosion or dirty pads, however, When I measure voltage on PIN 8 (CHGR_VNEG) it pulses with the fan (0.2v-1.5v) but if I leave the probe on that PIN or the TP after that for more than 5 seconds, the device will stop trying to boot, no fan spin, no pulsing voltage.
      Replugging the magsafe in or shorting SMC_ONOFF_L starts the pulsing and fan spinning again, is this something I should be concerned about?

      Comment

        #4
        Re: A1465 820-3435-B Fan spins on and off

        Fan on this board will spin-stop-spin-stop-spin when first applying power after Magsafe and battery are disconnected. If it does it infinitely not sure what that could be.
        Check if you get CPU VCore.
        OpenBoardView — https://github.com/OpenBoardView/OpenBoardView

        Comment

          #5
          Re: A1465 820-3435-B Fan spins on and off

          So I removed the J6100, however the same symptoms occur. Test points around it are slightly discoloured however are physically sound and test ok.

          @piernov Unfortunately it does it infinitely, and yes I get VCore pulsing between 0v-1.7v

          Comment

            #6
            Re: A1465 820-3435-B Fan spins on and off

            I would try to flash a new bios
            Check why pm_slp_s5 is fluctuating.
            What voltage is missing and causes it to go back and forth
            check for any short or missing voltages on S3 rails...
            Last edited by justin35; 02-29-2020, 06:21 AM.

            Comment

              #7
              Re: A1465 820-3435-B Fan spins on and off

              Yeah trying to flash BIOS is a good idea at that point.
              OpenBoardView — https://github.com/OpenBoardView/OpenBoardView

              Comment

                #8
                Re: A1465 820-3435-B Fan spins on and off

                I have a eeprom programmer arriving in the next couple of days, I'll give that ago.
                In the mean time I will continue to search for any incorrect voltages/shorts.
                Am I right in assuming the device needs PM_SLP_S5 present before it can go to S3/S0? (kind on the first step of booting).

                Comment

                  #9
                  Re: A1465 820-3435-B Fan spins on and off

                  Yes you are right, you need s5 state to be able to go to s4, then s3 and so on until s0 state. S0 is up and running.
                  S5 rails are always present, as long as magsafe and/ or battery is connected.
                  Explore the schematics pdf and you will find some info about machine states.

                  Comment

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