A1466 Missing Vcore

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  • mcplslg123
    Badcaps Legend
    • Jun 2015
    • 7262
    • india
    #1

    A1466 Missing Vcore

    Logic Board:820-00165A

    It turns on without display. Vcore is missing. Rest all voltage are there.

    01.All_Sys_PwrGood-3.3V
    02.P1V8S3_PGood-3.3V
    03.P1V05S0_Pgood-3.3V
    04.DDRREG_PGood-3.3V
    05.P5VS4RS3_PGood-3.3V
    06.S5_PGood-3.3V

    Missing
    01.CPU_VCCST_Pwrgd. R1931 Pin1 has P1V05S, pin2 is zero.Resistance on R1931,pin1 is 110 Ohms,PIn2 is 0.885K.
    02.U7200,PIn1 VR_EN is missing. CPU_VR_Ready is present on R1955. Resistance Value of R1800 is good.

    R1931 showed incorrect value and was rusted/frozen on CPU_VCCST_PGood side. I've restored the two pads and soldered 10K Resistor. MB doesnt turn on if R1931 is soldered. If i remove R1931,it turns on without Vcore.

    Can U1930 be bad or i'm on wrong path??
    U1930 measurements
    PIn1-PM_SLP_S3_L-3.3V
    Pin2-All_SYS_PGood-3.3V
    Pin4-CPU_VCCST_PG-0V
    Pin6-PP3V_S5-3.3V


    Have'nt done anything apart from measuring rails/voltages and replacing R1931 .

    Please advise how to move further. As said earlier, i dont have much knowledge on macbooks repair
    Last edited by mcplslg123; 08-17-2021, 12:01 AM.
    Tags: None
    • Askic
      Senior Member
      • Sep 2018
      • 187
      • BIH
      #2
      Re: A1466 Missing Vcore

      Hello mcplslg123,

      please measure:
      P3V3S0_EN and check whether you have 3v3_S0.
      U8030 is a switch that transfer 3v3 _S5 to 3V3_S0.

      When P3V3S0_EN is 3.3V, it will "move" 3V3_S5 to 3V3_S0

        Comment

        • piernov
          Super Moderator
          • Jan 2016
          • 4435
          • France
          #3
          Re: A1466 Missing Vcore

          PM_SLP_S5_L most likely pulsing with R1931 soldered. Check with oscilloscope.
          OpenBoardView — https://github.com/OpenBoardView/OpenBoardView

            Comment

            • mcplslg123
              Badcaps Legend
              • Jun 2015
              • 7262
              • india
              #4
              Re: A1466 Missing Vcore

              Originally posted by Askic
              Hello mcplslg123,

              please measure:
              P3V3S0_EN and check whether you have 3v3_S0.
              U8030 is a switch that transfer 3v3 _S5 to 3V3_S0.

              When P3V3S0_EN is 3.3V, it will "move" 3V3_S5 to 3V3_S0
              P3V3S0_EN & P3V3S0-Both are present with R1931 unsoldered.

                Comment

                • mcplslg123
                  Badcaps Legend
                  • Jun 2015
                  • 7262
                  • india
                  #5
                  Re: A1466 Missing Vcore

                  Originally posted by piernov
                  PM_SLP_S5_L most likely pulsing with R1931 soldered. Check with oscilloscope.
                  With R1931 soldered, there is nothing on PM_SLP_S5_L. Consumption on dc Supply starts with 0.0015amps and goes to 0.0026A. magsafe light goes from green to orange. With R1931 unsoldered, PM_SLP_S5_L is stable 3.3V. With R1931 unsoldered it turns on, consumption at 0.0150A with missing CPU_VCCST_PGOOD

                    Comment

                    • piernov
                      Super Moderator
                      • Jan 2016
                      • 4435
                      • France
                      #6
                      Re: A1466 Missing Vcore

                      Set trigger to single shot rising edge at like 1V on the oscilloscope if you can't see the pulse right away.
                      (maybe 500us/div horizontal)
                      OpenBoardView — https://github.com/OpenBoardView/OpenBoardView

                        Comment

                        • lamo
                          Member
                          • Nov 2017
                          • 38
                          • Ukraine
                          #7
                          Re: A1466 Missing Vcore

                          check these lines: svid_clk, svid_data and vid_alert. you should have some impulses at svid_data on CPU pwm ic.

                            Comment

                            • piernov
                              Super Moderator
                              • Jan 2016
                              • 4435
                              • France
                              #8
                              Re: A1466 Missing Vcore

                              Unrelated. SVID won't work if VCCST_PGOOD is missing.
                              OpenBoardView — https://github.com/OpenBoardView/OpenBoardView

                                Comment

                                • mcplslg123
                                  Badcaps Legend
                                  • Jun 2015
                                  • 7262
                                  • india
                                  #9
                                  Re: A1466 Missing Vcore

                                  @piernov, will check it. Btw, if it pulses what is the solution??

                                    Comment

                                    • piernov
                                      Super Moderator
                                      • Jan 2016
                                      • 4435
                                      • France
                                      #10
                                      Re: A1466 Missing Vcore

                                      https://logi.wiki/index.php/User:Pie....2C_what_do.3F
                                      OpenBoardView — https://github.com/OpenBoardView/OpenBoardView

                                        Comment

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