A1990 820-01041 usb-c issues

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  • rotceh_dnih
    Member
    • Jun 2020
    • 43
    • Australia

    #1

    A1990 820-01041 usb-c issues

    Hey guys working on a water damaged A1990 820-01041 and have it going now but the left usb-c ports will not mount or see a usb device unless you reboot/restart or cold boot with a drive in and it will work but eject it and replug and it will not show up.

    Any ideas where to start looking ?

    R3461 did look like crap so it was replaced Q3460 looked ok so i left it but not sure what the correct readings would be here nor if its related to my issue.
    Rain was sucked into it by the fans and it hit everywhere,the 2.5v&0.9v sdd rails were the worst hit and after the clean up it needed to be dfu restored for some reason

    its also very slow to come back from sleep after closing the lid regardless of how long it was left ie 2sec's or 2 hours it always takes 1 minute to come up but the usb issue is the biggest
  • mon2
    Badcaps Legend
    • Dec 2019
    • 13834
    • Canada

    #2
    Re: A1990 820-01041 usb-c issues

    Review the DIODE mode readings of each CCx lines.

    Meter in DIODE mode. Red meter lead to GROUND.

    Black meter lead to:

    USBC_XA_CC1_CONN
    USBC_XA_CC2_CONN

    USBC_XB_CC1_CONN
    USBC_XB_CC2_CONN

    and so on for each port.

    Post the readings.

    Do the same non-working ports negotiate the 20V power delivery contract with the external power adapter ?

    What is the voltage reading of PPBUS_G3H ?

    Slow boot can mean a sensor fault.

    Comment

    • rotceh_dnih
      Member
      • Jun 2020
      • 43
      • Australia

      #3
      Re: A1990 820-01041 usb-c issues

      Thankyou very much for the reply mate!

      LEFT BROKEN SIDE
      USBC_XA_CC1_CONN = 0.830v diode @ connector
      USBC_XA_CC2_CONN = 0.849v diode @ connector

      USBC_XB_CC1_CONN = 0.859v diode @ connector
      USBC_XB_CC2_CONN = 0.859v diode @ connector

      RIGHT WORKING SIDE
      USBC_TA_CC1_CONN = 0.857v diode @ connector
      USBC_TA_CC2_CONN = 0.860v diode @ connector

      USBC_TB_CC1_CONN = 0.841v diode @ connector
      USBC_TB_CC2_CONN = 0.857v diode @ connector

      Yes the non working side does charge 20v correctly and can hotplug charger no worries just not mounting usb unless you reboot

      PPBUS_G3H = 12.4v

      Not slow to boot but slow to wake after the lid has been shut.

      Comment

      • rotceh_dnih
        Member
        • Jun 2020
        • 43
        • Australia

        #4
        Re: A1990 820-01041 usb-c issues

        Welp my customer is going on holidays,Needs a reliable computer and this ain't it.

        Device has sold to me so Im extra keen now to get this one fixed.
        Might send it up to Paul D if i have no joy but have we got any other ideas or things to check?

        Comment

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