Shutting Down when plugging in

Discussion in 'MacBook Pro' started by dj2002rob, Jul 22, 2015.

  1. dj2002rob macrumors newbie

    Joined:
    Jul 22, 2015
    #1
    I have a mid 2012 MBP

    I have a mid 2012 MBP (i7 dual core) that drank a glass of water two days ago. I did a complete disassemble and a 99 ISO bath on the board. Also redid the thermal paste on the chips.

    The issues I'm having: after starting up, I was getting crazy (650%) kernel_task CPU usage and Apple Hardware Test results of: 4sns/1/40000000:ipbr-18.330 (Sensor, Current, Power bus is what i've deduced). Lately, i've been getting an occasional instant shutdown when I plug the charger in. At one point (earlier), the CPU would jump when I plugged the charger in.

    Seems like I have a hardware based power regulation issue that can cause the kernel to go crazy. I'm 14 hours in and don't know where to go. Time to send in?
     
  2. TheIguana macrumors 6502a

    TheIguana

    Joined:
    Sep 26, 2004
    Location:
    Canada
    #2
    You are probably going to need a new logicboard. You may be able to trace it down to a specific part on the board that has failed but I'm guessing that is going to be very time consuming.
     
  3. Rusty33 macrumors 6502

    Rusty33

    Joined:
    Jul 8, 2011
    Location:
    Australia
    #3
    Unfortunately it sounds like its time for your MBP to meet its maker...
     
  4. Dadioh macrumors 65816

    Dadioh

    Joined:
    Feb 3, 2010
    Location:
    Canada Eh?
    #4
    The current sensor for the PBUS (12.5V bus that feeds many of the secondary supplies on the logic board) has been affected by the spill. If the System Management Controller (SMC) detects any bad sensors then it loads the CPU with small tasks (kernel_task) that busies it out without causing thermal overload (you can google it). That is why you see the slow response. It is intended behavior.

    If you have access to a repair shop that has skill with the schematic/boardview and good soldering skills it is probably fixable.
     
  5. dj2002rob thread starter macrumors newbie

    Joined:
    Jul 22, 2015
    #5
    I got ahold of the schematic and board viewer and isololated the components related to the power system (U7000) and R5422. Using a small handheld microscope, I noticed a small copper filament (maybe, tough to tell) that was laying on the pin and essentially shorting it to other locations. I ISO scrubbed it off and, knock on wood, the issue seems to be resolved.

    Fortunately, the water was from a reverse osmosis system, so there was very little solute in the liquid.

    Fingers crossed that was the issue. Thanks for your contributions.
     
  6. Dadioh macrumors 65816

    Dadioh

    Joined:
    Feb 3, 2010
    Location:
    Canada Eh?
    #6
    Congrats! Yes it helps that it was pure water and you took all the appropriate steps quickly.

    Cheers
     

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