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[SOLVED]820-3330 stuck in a loop

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  • [SOLVED]820-3330 stuck in a loop

    Hi guys,
    The board stuck in an SMC_RESET loop, keeps on restarting every 2 seconds. Power pads don't work (shutting it down I mean). Had water damage over the U5750, U7000 area. Both were replaced.
    Concerning voltage, everything seems to be right and present. A hint anyone?
    Thanks

  • #2
    SMC_RESET going high and low? Green light?

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    • #3
      SMC_RESET_L stay at 3.0V , SMC chip was also replaced, problem persists. Green light is present

      Comment


      • #4
        PPBUS? PP3V3_S5? CPU Vcore?

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        • #5
          Ppbus_g3h=10.6v , pp3v3_s5=3.3v ,
          ppvcore_s0_cpu=1.1v , ppvcore_s0_axg=0v , pp1v05_s3_cpu_vccdq=1.5v , pp1v05_s0_cpu_vccpqe=1.05v , pp1v05_s0_cpu=0.8v

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          • #6
            I assume this was measured on battery else PPBUS is way too low.
            PP1V05 is of course not correct at 0.8V but makes no sense as pp1v05_s0_cpu_vccpqe is directly connected to it......

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            • #7
              PPBUS was measured with the charger connected, no battery attached.
              My bad, I meant:
              ppvcore_s0_cpu=1.1v , ppvcore_s0_axg=0v , pp1v05_s3_cpu_vccdq=1.5v , pp1v05_s0_cpu_vccpqe=1.05v ,PPVCCSA_S0_CPU=0.8V

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              • #8
                10.6 on PPBUS makes no sense. If Vcore is stable at 1.1V the fan should be running normal.

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                • #9
                  PPBUS is not stable. It changes from 3.3V to 10.7V (during this loopy process)

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                  • #10
                    Measure resistance between pins 17/18 and 27/28 from U7000 also check R7005 value........

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                    • #11
                      I guess you meant those 2 current sensing circuits, resistors R7020 and R7050 - those are measured at 0 ohm, as they should I think. R7005 is measured at 20 ohm so those look to be alright

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                      • #12
                        Read my request again and answer....

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                        • #13
                          The resistance between pins 17 and 18 is 0 ohm, also between 27 and 28. R7005 is 20 ohm. Thank you for your replies

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                          • #14
                            between 17 and 18 should be 2.2ish. Check what is going on there.

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                            • #15
                              Thank you. One line from the two was cut and fixed. Now PPBUS measured at 12.7V, the device finally runs.
                              It is getting into sleep mode randomly and ASD shows only one error with VP0R sensor, which is measured too low

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