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iMac (21.5‐inch, Late 2013) 820-3588-A

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    iMac (21.5‐inch, Late 2013) 820-3588-A

    Ciao a tutti...I hope to be in the right place,

    the car in question is:
    iMac (21.5‐inch, Late 2013)
    Model Number: A1418
    EMC Number: 2638
    Speed: 2.7 GHz
    Type: Intel Core i5 (4th Gen) (Crystal Well) Model: 4570R
    Cores: 4
    Graphics Card: Intel Iris Pro 5200

    The problem lies in the logic board Model Number 820-3588-A

    Symptom:
    started correctly then suddenly went out. If I leave it off for several hours and then try to start it, LED 1 lights up then LED 2 then goes off after 10 seconds (photo01) and if I try again, only LED 1 lights up for a second (photo02) and that's it.

    I have two tested and operated power supplies but the problem persists.

    Any advice will be well received.
    Thanks

    #2
    Re: iMac (21.5‐inch, Late 2013) 820-3588-A

    Still sounds like a power supply issue so confirm your power supplies are still working with another main logic board if possible.
    If it is indeed a main logic board issue, measure voltages on the G3H and S5 power rails listed on page 70 of the schematics.
    OpenBoardView — https://github.com/OpenBoardView/OpenBoardView

    Comment


      #3
      Re: iMac (21.5‐inch, Late 2013) 820-3588-A

      Photo...
      Attached Files

      Comment


        #4
        Re: iMac (21.5‐inch, Late 2013) 820-3588-A

        Hi Piernov,
        then not only alone, thanks for listening to me.

        I used two power supplies and both tested on a working iMac.
        ---------------------------------------------------------------------
        G3 Rails


        PP3V3_G3
        -------- PP3V3_G3_RTC 3.2V
        -------- =PPVRTC_G3_PCH 3.2V


        G3H Rails
        PP12V_ACDC
        ---------- PP12V_G3H_ACDC 12V
        ---------- =PP12V_G3H_SNS_R 12V

        PP12V_G3H
        --------- PP12V_G3H_SNS 12V
        --------- =PP12V_G3H_REG_3V42_G3H 12V
        --------- =PP12V_G3H_FET_P12V_S0 12V
        --------- =PP12V_G3H_FET_P12V_S0 12V
        ---------- =PP3V3_G3H_SMC
        ---------- =PP3V3_G3H_RTC_D 3.40V
        ---------- =PPVIN_G3H_SMCVREF 3.40V
        ---------- =PP3V3_G3H_SMC_USBMUX 3.40V
        ---------- =PP3V3_G3H_LPCPLUS 3.40V

        Comment


          #5
          Re: iMac (21.5‐inch, Late 2013) 820-3588-A

          S5 Rails
          Enabled when system has AC and is in S5

          PP12V_S5
          -------- PP12V_S5_FET
          Q6970 OUT 0.324V
          -------- =PP12V_S5_REG_P3V3P5V_S5
          C7610 0.324V
          -------- =PP12V_S5_REG_VDDQ_S3
          C7310 0.324V
          -------- =PP12V_S5_PWRCTL
          C8430 0.324V
          -------- =PPHV_SW_TBTAPWRSW
          C3210 0.324V
          -------- =PPHV_SW_TBTBPWRSW
          C3310 0.324V
          -------- =PP12V_S5_SNS
          R5401 0.324V

          --------------------------------------

          PP5V_S5
          ------- PP5V_S5_LDO
          C7601 0.030 FLOATING rising
          ------- =PP5V_S5_PWRCTL
          C8400 0.033V
          Q7600 pin4 0.033V
          R7601 0.033V


          -------------------------------------

          PP5V_S5
          ------- PP5V_S5_LDO
          C7601 0.030 FLOATING rising
          ------- =PP5V_S5_PWRCTL
          C8400 0.033V
          Q7600 pin4 0.033V
          R7601 0.033V

          Comment


            #6
            Re: iMac (21.5‐inch, Late 2013) 820-3588-A

            I specify that these measurements are made exclusively with the power supply and logic board but the LEDs are inactive.

            Comment


              #7
              Re: iMac (21.5‐inch, Late 2013) 820-3588-A

              Measure voltage on SMC_PM_G2_EN.
              Measure resistance to ground on PP5V_S5_LDO, PP3V3_S5 and PP5V_S4.
              OpenBoardView — https://github.com/OpenBoardView/OpenBoardView

              Comment


                #8
                Re: iMac (21.5‐inch, Late 2013) 820-3588-A

                SMC_PM_G2_EN
                measurement performed on PIN2 of the U6970 is 3.4V

                PP5V_S5_LDO
                6,070 Mohm on R7602 on GND

                I'm sorry piernov,
                but for PP3V3_S5 and PP5V_S4
                what resistances I need to measure?

                Comment


                  #9
                  Re: iMac (21.5‐inch, Late 2013) 820-3588-A

                  Sorry Piernov,
                  but you were referring to the resistance of the rails?
                  To be taken in diode mode and with positive tip on the ground?

                  Let me know if I misunderstood.
                  Thank you

                  Comment

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