Macbook Air A 2681 Board 820-02536 No turn on

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  • Sergio Kub
    Senior Member
    • Jul 2018
    • 169
    • Brasil

    #1

    Macbook Air A 2681 Board 820-02536 No turn on

    Hello,
    I have a Mac A2681 motherboard 820-02536. It was spilled in water. I had already cleaned it with isopropyl alcohol and managed to get it working. However, the keyboard, touchpad, and power button failed.
    A month later, I replaced these components, and the motherboard no longer turns on.
    F5200 resistance: 1 M Ohm
    Stuck at 5V
    Voltage doesn't pass the first transistor, Q5230
    Can anyone help? I couldn't find the sequence.
    I appreciate any tips or collaboration in advance.
  • mon2
    Badcaps Legend
    • Dec 2019
    • 14307
    • Canada

    #2
    F5200 resistance: 1 M Ohm
    ?? Power up and measure the voltage to ground on each side of F5200. Post the measurements. If this is the measurement across F5200 then the fuse is blown and needs to be replaced.

    Without power to the board, measure the resistance to ground on each side of F5200. If the fuse is not blown, this measurement should be the same on each side.

    Comment

    • Sergio Kub
      Senior Member
      • Jul 2018
      • 169
      • Brasil

      #3
      Thanks for responding.
      The fuse is not blown.
      Without power to the board, the resistance measurement on the F5022 is high, around 1M Ohm.
      The voltage does not pass through Q5230, right at the input.

      Comment

      • mon2
        Badcaps Legend
        • Dec 2019
        • 14307
        • Canada

        #4
        Share the voltage to ground measurements of each pin on q5230:

        source
        gate
        drain

        Comment

        • Sergio Kub
          Senior Member
          • Jul 2018
          • 169
          • Brasil

          #5
          It is a double transistor
          First
          Pin 3, 4 and 5 D - 5V
          Pin 6 G - 0V
          Pin 7 S - 0V
          Consequently, the second transistor with all pins 0V,

          Comment

          • mon2
            Badcaps Legend
            • Dec 2019
            • 14307
            • Canada

            #6
            Remove all power. Meter in resistance mode.

            Measure the resistance across:

            source & drain
            source & gate
            gate & drain


            post each measurement.

            Comment

            • Sergio Kub
              Senior Member
              • Jul 2018
              • 169
              • Brasil

              #7
              S - D 700 K Ohm
              S - G 350 K Ohm
              G -D 6.37 M Ohm

              Comment

              • Sergio Kub
                Senior Member
                • Jul 2018
                • 169
                • Brasil

                #8
                Q5230 / 2
                S - D 800K Ohm
                S - G 700K Ohm
                G - D 427K Ohm

                Comment

                • mon2
                  Badcaps Legend
                  • Dec 2019
                  • 14307
                  • Canada

                  #9
                  The G-D measurement may be a bit low for the mosfet. Suggest to flux and remove this mosfet. Leave the mosfet off the board. Then power up again.

                  Does the first mosfet enable without this 2nd mosfet on the board?

                  Comment

                  • Sergio Kub
                    Senior Member
                    • Jul 2018
                    • 169
                    • Brasil

                    #10
                    Q5230 are 2 transistors in the same package. It's dual.
                    Should I remove the first one anyway?

                    Comment

                    • Sergio Kub
                      Senior Member
                      • Jul 2018
                      • 169
                      • Brasil

                      #11
                      There are two dual MOSFETs at the power input, Q5230 and Q5240.
                      The resistances measured were from the two MOSFETs in the first package. Q5230

                      Comment

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