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Macbook pro A2779 820-02841-A 5v stuck

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  • fricosu007
    Member
    • Feb 2016
    • 48
    • romania
    #1

    Macbook pro A2779 820-02841-A 5v stuck

    Hello !
    got stuck with a macbook pro a2779 / 820-02841-A having a short on pp5v_s2_main, found the issue, it was the UC260 who got toasted, i replaced if from a donor board, now pp5vs2_sw oscilates between 2v and 4v but never steady on 5v, no more short, could be the u5200 ? I cannot find what ic is making the 5v for S2 rail … power line is at 5v/0.1amp drow, ppvin_p5vs2 is 12v steady … please help !
    Tags: None
    • mon2
      Badcaps Legend
      • Dec 2019
      • 16541
      • Canada
      #2
      Remove all power. What is the exact resistance to ground in ohms at pp5vs2_sw?

        Comment

        • fricosu007
          Member
          • Feb 2016
          • 48
          • romania
          #3
          Originally posted by mon2
          Remove all power. What is the exact resistance to ground in ohms at pp5vs2_sw?
          It’s 400kohm and dropping

            Comment

            • mon2
              Badcaps Legend
              • Dec 2019
              • 16541
              • Canada
              #4
              The resistance is ok.

              What is the exact netname for pp5vs2_sw? This label does not appear in my schematic. Use only the exact name as in the schematics.

                Comment

                • fricosu007
                  Member
                  • Feb 2016
                  • 48
                  • romania
                  #5
                  Originally posted by mon2
                  The resistance is ok.

                  What is the exact netname for pp5vs2_sw? This label does not appear in my schematic. Use only the exact name as in the schematics.
                  sorry for late replay, been away for some time but issue is still on my desk ..


                  P5VS2_SW from UC260 which i found burnt and replaced

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