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MacBook Pro A1990 No power

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    MacBook Pro A1990 No power

    Hi, I have an A1990 board 820-01041-A, no corrosion or liquid.
    The NANDs on the left (immediately are getting warm after 10 seconds or so, then get hot) - no power. The trackpad was clicking, after trying DFU revive it doesn't click any longer.

    Board is taking 20V and bouncing between 0.1A and 0.7A
    PPBUS_G3H is present bouncing between 10.6V and 12.5V
    PP2V5_NAND_SSD0 is shorted to ground
    PP1V8_SSD0 is present 1.8V

    I will check tomorrow under thermal camera once I am back in the shop, with my novice knowledge does this mean SSD is dead?

    #2
    Re: MacBook Pro A1990 No power

    Remove all power. Meter in resistance mode.

    Check the resistance to ground of PPBUS_G3H. A low resistance means someone is pulling this line down.

    Is this rail pulsing normal to low to normal voltage ?

    Consider to desolder F7000 & F7001 fuses.

    Then power up again. Check if PPBUS_G3H @ pin # 1 of these same fuse pads is now stable or is it still pulsing or is a low voltage value ?

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      #3
      Re: MacBook Pro A1990 No power

      PPBUS_G3H is roughly 1.1K but it is going down slowly, cant get a stable reading, but it is not shorted (is this normal because there area many components on this line? Sorry, I am still a beginner )

      The rail when checking today is between 12.3 to 12.6, every 5 seconds or so switches between one of these voltages.

      3 SSD Nands are getting hot, and there was scorch marks on U9080.
      PP2V5_NAND_SSD0 is 1.5Ohms, removing U9080 and U9000 has made no difference to this resistance.





      Am I right to think from this, that SSD NANDs have internal short? I know tantalum caps can sometimes fail on these, like C9087 to C9091, but at this stage it looks like there is no hope I guess?
      Last edited by ronaldopdias; 08-13-2022, 02:58 AM.

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