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820-3437 - Does RTC reset over and over.

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  • 820-3437 - Does RTC reset over and over.

    Had liquid damage on C1910, which I replaced.

    Could this be a faulty U1900?

    It looks like an RTC reset that repeats ad nauseam.

  • #2
    Do you get variations at pin1?
    It must be always high.
    Remove U1900 and clean all that area and its pads; then resolder it.
    Pin12 has stable clock?

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    • #3
      U1900::1 is going up and down.

      I'll replace it and report back.

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      • #4
        Be sure first if U1900 is correctly powered up...

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        • #5
          Just noticed that PP3v3_S5 is power cycling.
          Didn't pick up on it the first time I looked.

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          • #6
            if pp3v3_s5 is power cycling something up the line is shorted to ground.

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            • #7
              PPBUS even stable? 3v3_s5 pulsing could also be G2_EN pulsing. S5_pwrgd coming high?

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              • #8
                PPBus is stable.

                It seems to be boot every now and then, but mostly power cycles.
                Will check G2_EN and S5_pwrgd in a moment.

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                • #9
                  S5_pwrgd is stable.

                  Ugh, G2_EN is cycling. But every five or ten powers I can get it stable, then it boots fine.

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                  • #10
                    SMC issue, probably crap under it.

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