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820-3476 green light, no boot. Weird 5V rail behaviour

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  • 2informaticos
    replied
    "Check if SMC_RESET_L is stable."
    ???

    Check for pulse at least on the coils...

    Leave a comment:


  • kevinklinkmuller
    replied
    thank you,tried it on this one and nothing

    Leave a comment:


  • 2informaticos
    replied
    Press power button, connect charger and maintain pressing 5-10s...

    Leave a comment:


  • kevinklinkmuller
    replied
    ok, have tried smc bypass mode, doesn't work

    Leave a comment:


  • kevinklinkmuller
    replied
    is SMC bypass where i have to run a wire to ground repeatedly? How do I do that? thanks!

    Leave a comment:


  • 2informaticos
    replied
    So SMC_PM_G2_EN is not stable; or SMC detects a problem and pull it down.
    Try to start in SMC bypass mode first.
    Check if SMC_RESET_L is stable.

    Leave a comment:


  • kevinklinkmuller
    replied
    PPbus is 12.58v

    U7501
    pin 23 is 12.58
    pin 13 is pulsing between 0 and 2v
    pin 22 is 3.3v
    pin 29 is is sometimes 0, 2.5 and 5
    pin 12 pulsing between 0 and 3.3
    pin 21 pulsing between 0 and 3.4
    pin 4 0v

    3v42 is stable at 3.4v

    Leave a comment:


  • 2informaticos
    replied
    Post exact voltage for PPBUS_G3H.
    Also post some voltages for U7501, pins 23, 13, 22, 29, 12, 21, 4.
    Stable 3V42 power rail?

    Leave a comment:


  • JohnB8812
    replied
    If PP5v_S5 is pulsing, it could very well be from a poorly soldered or bad TPS51980.

    Leave a comment:


  • 820-3476 green light, no boot. Weird 5V rail behaviour

    Have an 820-3476 with green light. I think it had liquid damage initially but someone else has already messed with the board so i can't really tell

    It has green light. Have started going down the power rail list. everything looks normal and i've stopped at the 5v rails because they are acting strange. Evertime I measure it's a different number. Sometimes it's 0, sometimes it's 2.5 and sometimes it's 5. I don't see it change when i'm holding the probes on it but when i release the probes and put them back on it's a different number again.

    The thing I see that has definitely been messed with is
    u7501

    Shall i keep going down the power rail list or am i on the right track?

    Thanks!

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