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iMac 21.5" Mid Late 2015 820-00430-A no clue

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  • #16
    So no CPU VCORE, board cannot work.
    Check for enable signals at pins 16/17 of U7300.
    Also check if receives 5V at pin 12.

    Comment


    • #17
      U7300 pin 12 5v, pin 16 3.3v pin 17 0v

      Comment


      • #18
        Then you cannot have 0.6V at DDRVTT yet, as pin 17 is not enabled.
        But you must have 1.2V at L7310; confirm that.

        DDRVTT is enabled by CPU.

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        • #19
          Confirmed, I do have 1.193v at
          L7310

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          • #20
            Do you get 1V05_S0 and 1V5_S0?
            Also check all voltages from page 63.

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            • #21
              PP1V05_S0 is 0.005 and PP1V5_S0 is 0v

              Power rails missing are PP1V2_S3_DDR, PP3V3_S0, PP1V5_S0 and PPCPUVCC_S0_CPU

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              • #22
                Are you sure???
                You just confirmed 1.2V at L7310 before...

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                • #23
                  yes sorry
                  PP1V2_S3 and PP1V2_S3_DDR are present but not PP3V3_S0, PP1V5_S0 and PPCPUVCC_S0_CPU

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                  • #24
                    Post U8400/500 voltages.

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                    • #25
                      U8400 1-3.3v 2-3.3v 3-3.3v 4-5v 5-0v 6-3.3v 7-3.3v 8-0v 9-0v 10-0v 11-0v 12-11v 13-3.3v 14-3.3v

                      U8500 1-3.3v 2-3.3v 3-3.3v 4-3.3v 5-3.3v 6-3.3v 7-G 7--14-3.3v

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                      • #26
                        Looks like missing PM_SLP_S3_L; check that.
                        Also check REG_P1V2_S3_PGOOD at U7300.
                        Be sure =PP3V3_S4_PWRCTL and R7340 OK.

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                        • #27
                          PM_SLP_S3_L present 3.3v
                          PM_PGOOD_REG_P1V2_S3 3.3v at U7300 R7340 is 19.49k checking real value now as I dont see that resistor on the schematic

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                          • #28
                            Whats strange is that
                            R7340 is ok at 19.49k but
                            PM_PGOOD_REG_P1V2_S3 is 3.3v not 1.2v

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                            • #29
                              Mmmm, I just saw that in fact you didn't post any voltage for pins 8/9/10 of U8500.
                              I was reading values from U8400 instead.

                              Do you get PM_EN_S0?

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                              • #30
                                PM_EN_S0 is 3.3v at U8500

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