Dell Latitude e6430 problem inversion of polarities

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  • nejib01
    Member
    • Aug 2014
    • 12
    • Algeria

    #1

    Dell Latitude e6430 problem inversion of polarities

    Hi ,
    After polaritie reverse of the power supply my laptop works only without battery (motherboard QAL81 LA-7782P) , can you help me to solve this problem.
    Thanks
    Last edited by nejib01; 09-03-2022, 04:32 PM.
  • mon2
    Badcaps Legend
    • Dec 2019
    • 13830
    • Canada

    #2
    Re: Dell Latitude e6430 problem inversion of polarities

    You will have to review the 2*DCin mosfets.

    Remove all power. Meter in resistance.

    Check the resistance of the mosfet pins:

    Source and drain
    Source and gate
    Gate and drain

    Post each measurement. Repeat for the next mosfet.

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    • nejib01
      Member
      • Aug 2014
      • 12
      • Algeria

      #3
      Re: Dell Latitude e6430 problem inversion of polarities

      Thanks for replying.
      do you mean these two ones near dc input in picture
      Attached Files

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      • mon2
        Badcaps Legend
        • Dec 2019
        • 13830
        • Canada

        #4
        Re: Dell Latitude e6430 problem inversion of polarities

        It is a good start. What are the markings on these 8 pin mosfets?

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        • nejib01
          Member
          • Aug 2014
          • 12
          • Algeria

          #5
          Re: Dell Latitude e6430 problem inversion of polarities

          4423 / 4435 and i think the second one short (all drain - source - gate make bips on multimeter)
          Last edited by nejib01; 09-04-2022, 04:46 PM.

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          • mon2
            Badcaps Legend
            • Dec 2019
            • 13830
            • Canada

            #6
            Re: Dell Latitude e6430 problem inversion of polarities

            Good. If you have a good replacement for this mosfet, replace it and test again.

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            • nejib01
              Member
              • Aug 2014
              • 12
              • Algeria

              #7
              Re: Dell Latitude e6430 problem inversion of polarities

              Thanks a lot i found mosfet 4435bz by chance and everything works like a charm ,my laptop detect the battery now .

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              • mon2
                Badcaps Legend
                • Dec 2019
                • 13830
                • Canada

                #8
                Re: Dell Latitude e6430 problem inversion of polarities

                Well done. Thanks for the thread closure.

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