A1278 sensor issue

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  • korijs123
    New Member
    • Feb 2018
    • 3
    • Latvia

    #1

    A1278 sensor issue

    Hello,

    I am doing repair for Macbook Pro A1278 (APPLE A1278 820-2936-A).
    These are the sympthoms:
    1. when turn on the macbook i have to push the power button until the chimes sound if not it can not be turn on.
    2. after turn on the macbook is very lagging. so when i check the activity monitor it shows kernel task over 300%.

    So i tried some action:
    1. reinstall the mac os x -- nothing changed
    2. change the battery -- nothing changed
    3. take out all the connector (wifi, speaker, dvdrom) -- nothing changed
    4. try to safe mode boot - kerner_task below 50% and no lagging.
    5. try to do AHT -- shows error 4SNS/1/40000000:IB0R-9.166
    6. smc reset and still nothing.

    The code seems to be for Sensor for current battery or something, "I" current, "B" for battery i think. I know how to take capacitors and stuff like that off, and changing them, just i need to know where to start looking.
    I only want to know where in schematics i need to look.
    I have all the tools and basic knowladge.
    Thanks

    P.S. this macbook pro has no water damage.
  • piernov
    Super Moderator
    • Jan 2016
    • 4435
    • France

    #2
    Re: A1278 sensor issue

    R7050-R7052 on the schematics.
    Also make sure you're using a good battery, you may try to read the sensor value without the battery (should be 0).
    OpenBoardView — https://github.com/OpenBoardView/OpenBoardView

    Comment

    • korijs123
      New Member
      • Feb 2018
      • 3
      • Latvia

      #3
      Re: A1278 sensor issue

      Originally posted by piernov
      R7050-R7052 on the schematics.
      Also make sure you're using a good battery, you may try to read the sensor value without the battery (should be 0).
      Ill try that, but i dont think its the battery. it has the same issue when i remove the battery.

      Comment

      • dmartins
        David M
        • Apr 2014
        • 197
        • Lisbon

        #4
        Re: A1278 sensor issue

        Hello ,

        I have exactly the same problem , this computer is very slow , 16GB Ram , SSD ...
        Fan is always high speed .

        You already solved your computer?

        Thanks

        Comment

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