A1278 MBP 820-3115-B powers up no chime

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  • Gimi
    Senior Member
    • Aug 2015
    • 75
    • UK
    #1

    A1278 MBP 820-3115-B powers up no chime

    Hi. got this macbook trying to repair and for last 2 days is sending me mad. Anyway it has been liquid damadged and after ultrasonic clean is now powering on with no chime. all around cpu i get short to ground.L7510,L7520,L7550,L7630,L7100 etc
    I have checked for bad traces and damadged components but nothing visual.
    Q7510,Q7520 gets 12v on pin 2 but pin 3 and 4 are shorted, would them 2 be the problem?
    Any help? Thanks
    Tags: None
    • tata123
      Senior Member
      • Nov 2013
      • 104
      • Germany
      #2
      Re: A1278 MBP 820-3115-B powers up no chime

      Hey!

      Check if CPU or Northbridge get hot?
      Check the RTC clock gen!
      Check SMC or BIOS!

        Comment

        • Gimi
          Senior Member
          • Aug 2015
          • 75
          • UK
          #3
          Re: A1278 MBP 820-3115-B powers up no chime

          Hi. Thanks for your help. will be looking at that this weekend. Much appricieted .

            Comment

            • Parkhaus
              New Member
              • Dec 2017
              • 1
              • USA
              #4
              Re: A1278 MBP 820-3115-B powers up no chime

              I have a similar problem,, I have a dim green light on the magsafe, fans spin immediately after plugging it in and I can turn it OFF by holding the button. Going to check PPBUS_G3H when I get home for short to power, but where could that happen, within the CPU?

                Comment

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