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820-2915, not turning on, has green light

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  • 820-2915, not turning on, has green light

    Hi guys,

    This 820-2915 came in with green light and most voltages present, I say most cause since its not powering on something surely is missing.

    It seems it was LD through the USB ports side - no extreme corrosion present - I UC it before anything else.

    PPBUS_G3H at 12,5V
    PP3V42_G3H at3,41V
    P3V3_S5 also normal
    Battery pulses are present - I assume this means the SMC is working and tries to talk to the battery
    and there is a green light...


    on the other hand
    SMC_RESET_L is constantly high

    also PPVBAT_G3H_CONN starts at 12,5V and drops to 5V so does CHGR_BGATE, then it repeats as long as the PSU is connected.

    I replaced U7000 already and measured the two current sense points with normal values.


    EDIT1: I measured around and found PP3V3_S4 to appear at some point but at 0.5 to 1.5V and fluctuating. The PP3V3_S4 FET and its surrounding components are missing - still looking to see where this comes from.

    EDIT2: PM_SLP_S4_L not present at R7913/pin2.

    Why all the funny ones come to me? I mean I really need one or two with just a blown BKL fuse to maintain mental health...

    thanks in advance guys.
    Last edited by george-a; 05-20-2016, 11:41 AM.

  • #2
    It is power cycling. This could be many things, but I first you need to verify that all power is pulsing. One of them will be missing so the PGOOD will not come high. Follow the corrosion.....

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    • #3
      Originally posted by dukefawks View Post
      It is power cycling. This could be many things, but I first you need to verify that all power is pulsing. One of them will be missing so the PGOOD will not come high. Follow the corrosion.....
      hi duke, thank you for the input.

      so you mean the PGOOD will show up momentarily for every power rail? do I do this with magsafe always connected and wait for the power cycles or by connect/measure/disconnect/repeat?

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      • #4
        Is ALL_SYS_PWRGD also pulsing, will be hard to catch on multimeter, scope is better.

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