A1707 no CPU Vcore

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  • megabitit
    Member
    • Apr 2020
    • 10
    • Portugal

    #1

    A1707 no CPU Vcore

    Hello Guys,

    I have an A1707 820-00281-A, that doesn´t boot, that has 19.5V and stays at 20mA current, and drops to 0mA. All major rails voltages are ok, but I have 0V on L7211. I'm thinking in replacing the U7210.

    Can anyone help me?
  • piernov
    Super Moderator
    • Jan 2016
    • 4435
    • France

    #2
    Re: A1707 no CPU Vcore

    If you only have 20mA you are probably missing more than just CPU VCore.
    Please go down the list of power rails to check their voltage so we can understand what state the board is in. Also describe history of the machine (liquid damage, physical damage…) and confirm you are using a known good genuine Magsafe 87W.
    And don't replace U7210, there is no reason to.
    OpenBoardView — https://github.com/OpenBoardView/OpenBoardView

    Comment

    • MobileXT
      Senior Member
      • Oct 2012
      • 191
      • USA

      #3
      Re: A1707 no CPU Vcore

      Do you have PPBUS_G3H?

      Comment

      • megabitit
        Member
        • Apr 2020
        • 10
        • Portugal

        #4
        Re: A1707 no CPU Vcore

        Thank you guys.

        Yes, i do have PPBUS_G3H.

        I´m measuring all the power rails, and i´ll post them hear today. If anyone can help me, i´ll be apreciated guys.

        Comment

        • megabitit
          Member
          • Apr 2020
          • 10
          • Portugal

          #5
          Re: A1707 no CPU Vcore

          Thank you piernov. I´m measuring all the power rails, and i´ll post them hear today. If you can help me, i´ll be apreciated.

          Comment

          • megabitit
            Member
            • Apr 2020
            • 10
            • Portugal

            #6
            Re: A1707 no CPU Vcore

            Yes MobileXT, i do have PPBUS_G3H.

            Comment

            • megabitit
              Member
              • Apr 2020
              • 10
              • Portugal

              #7
              Re: A1707 no CPU Vcore

              Good afternoon,

              The board just stoped working. It has no liquid damages or anything else... just stop working.

              Here are the measurements I got:

              PPBUS_G3H = 12.58V
              PPBUS_HS_CPU = 12.58V
              PPBUS_HS_GPU = 12.58V
              PPBUS_HS_OTH5V = 12.58V
              PPBUS_HS_OTH3V3 = 12.58V
              PPBUS_S4_HS_TPAD = 12.58V
              PPVCC_S0_CPU = 0V
              PPVCCSA_S0_CPU = 0V
              PPVCCGT_S0_CPU = 0V
              PPVCCIO_S0_CPU = 0V
              PP3V3_G3H = 3.4V
              PP3V0_G3H = 3.0V
              PP1V2_S3 = 0V
              PP1V2_S3_CPUDDR = 0V
              PP1V2_S0SW = 0V
              PP0V6_S0_DDRVTT = 0V
              PP0V6_S3_MEM_VREFD0_A = 0V
              PP0V6_S3_MEM_VREFCA_A = 0V
              PP0V6_S3_MEM_VREFD0_B = 0V
              PP1V8_SUS = Fluctuates between 1.4V and 0.5V
              PP1V8_S4 = 0V
              PP1V8_S3 = 0V
              PP1V8_S3_MEM = 0V
              PP1V8_S0 = 0V
              PP1V0_SUS = Fluctuates between 0.6V and 0V
              PP1V0_S3 = 0V
              PP1V0_S0SW = 0V
              PP3V3_S5_T139 = Fluctuates between 0V and 3.3V
              PP3V3_S4_SOC_PMU = 0V
              PP5V_S0_T139 = Fluctuates between 1V and 0.5V
              PP3V3_S5 = Fluctuates between 0V and 5V
              PP3V3_SUS = 0V
              PP3V3_S4 = 0V
              PP5_S4 = 0V
              PP5V_S0 = 0.5V
              PP3V3_S4_T151 = 0V
              PP3V3_S0 = Fluctuates between 0V and 0.5V

              Can anyone help?

              Comment

              • piernov
                Super Moderator
                • Jan 2016
                • 4435
                • France

                #8
                Re: A1707 no CPU Vcore

                Originally posted by megabitit
                Good afternoon,
                PP3V3_S5 = Fluctuates between 0V and 5V
                I assume that's a typo since PP3V3_S5 should only go up to 3.3V.

                Also I don't see PP5V_S5 in this list (and some others but should not be relevant for now).

                Measure resistance to ground on PP3V3_SUS and PP5V_S4.
                OpenBoardView — https://github.com/OpenBoardView/OpenBoardView

                Comment

                • shaban
                  New Member
                  • Oct 2011
                  • 4

                  #9
                  Re: A1707 no CPU Vcore

                  PP3V3_S5_T139
                  never fluctuates constantly 3.3 volts

                  Comment

                  • megabitit
                    Member
                    • Apr 2020
                    • 10
                    • Portugal

                    #10
                    Re: A1707 no CPU Vcore

                    Hello piernov.

                    the PP5V_S5 = Fluctuates between 0V and 5V

                    The resistance of the PP3V3_SUS = 3M Ohm
                    The resistance of the PP5V_S4 = 5M Ohm

                    The PP3V3_S5 = Fluctuates between 0V and 3.3V

                    I have no idea of what's causing this

                    Comment

                    • megabitit
                      Member
                      • Apr 2020
                      • 10
                      • Portugal

                      #11
                      Re: A1707 no CPU Vcore

                      The PP3V3_S5_T139 = Fluctuates between 0V and 3.3V

                      Comment

                      • megabitit
                        Member
                        • Apr 2020
                        • 10
                        • Portugal

                        #12
                        Re: A1707 no CPU Vcore

                        Does anyone has any ideas? What should I check now?

                        Comment

                        • sunny1234
                          New Member
                          • Dec 2020
                          • 1
                          • Berlin

                          #13
                          Re: A1707 no CPU Vcore

                          Have you solved the problem, if yes what have you done? If not, can anyone help here I have the exact same problem.

                          Comment

                          • meineiid
                            New Member
                            • Jan 2019
                            • 9
                            • Germany

                            #14
                            Re: A1707 no CPU Vcore

                            Hi there,,

                            i have the same issue too

                            Comment

                            • josuecas
                              New Member
                              • Mar 2019
                              • 2
                              • Honduras

                              #15
                              Re: A1707 no CPU Vcore

                              replace u7800

                              Comment

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