Announcement

Collapse
No announcement yet.

Macbook Core i7 2010 a1286 820 - 2850A CRAZY JUMPING voltages

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

    Macbook Core i7 2010 a1286 820 - 2850A CRAZY JUMPING voltages

    Hello

    Need just to know how do you guys determine what the problem is, when we have some fluctuating volt, to discard a faulty TPS 51125 , or if the issue is after this IC.

    CRAZY JUMPING

    PP3V3_S5 = 0v to 3.33 v jumping
    PPBUS_G3H = 12.4v to 12.48 jumping a little
    PP5V_S5 = 2v to 5v aprox, jumping fast
    P3V3S5_ENTRIP = crazy jumping from low volt
    SMC_PM_G2_EN = jumping 0v to 3.3v crazy


    STEADY


    P3V42_G3H=3.39V steady
    PP5V1_CHGR_VDD=5.06v steady
    PPCHGR_DCIN= 18.29 to 18.31 jumping



    thanks for any help in advance, can measure whatever you need and also have a working similar board but 2011.



    Attached Files
    Marcelo J

    #2
    Re: Macbook Core i7 2010 a1286 820 - 2850A CRAZY JUMPING voltages

    Power down / remove battery.

    Meter in resistance mode (200 ohms). Check the resistance to ground on each and every coil on the logic board.

    Checking for very low resistance readings for potential shorted caps. The CPU rail is expected to be a low reading - that is normal.

    Comment


      #3
      Re: Macbook Core i7 2010 a1286 820 - 2850A CRAZY JUMPING voltages

      L7330=27kohm
      L7530=41.5ohm
      L9560=113.2ohm
      L8920=2.5ohm (GPU..... I'm aware of this macbooks issues here but this might be ok, who knows)
      L7425=132.7ohm
      L7415=132ohm
      L7630=23.7ohm
      L7030=1.99Mohm
      L7220=23kohm
      L7720=0.234kohm

      The Macbook has only green led does not power on, no water damage, unknown history, connected to my bench with magsafe 1 power cord, and cycling from 8mah to 23mah consumption. does not start fans (no battery attached)

      thanks mon2
      Last edited by marce002; 09-09-2021, 09:10 AM.
      Marcelo J

      Comment


        #4
        Re: Macbook Core i7 2010 a1286 820 - 2850A CRAZY JUMPING voltages

        Just to test... removed main fuse f7040 and ppbus_g3h is stable as usual.. so not blame u7000.
        Marcelo J

        Comment


          #5
          Re: Macbook Core i7 2010 a1286 820 - 2850A CRAZY JUMPING voltages

          Originally posted by marce002 View Post
          L7330=27kohm
          L7530=41.5ohm
          L9560=113.2ohm
          L8920=2.5ohm (GPU..... I'm aware of this macbooks issues here but this might be ok, who knows)
          L7425=132.7ohm
          L7415=132ohm
          L7630=23.7ohm
          L7030=1.99Mohm
          L7220=23kohm
          L7720=0.234kohm

          The Macbook has only green led does not power on, no water damage, unknown history, connected to my bench with magsafe 1 power cord, and cycling from 8mah to 23mah consumption. does not start fans (no battery attached)

          thanks mon2
          What's the resistance to ground of L7260?

          Comment


            #6
            Re: Macbook Core i7 2010 a1286 820 - 2850A CRAZY JUMPING voltages

            sorry i forgot that one because it is under the speaker.... it is

            L7260=8.77kohm
            L9701=0.400Mohm
            Last edited by marce002; 09-09-2021, 03:49 PM.
            Marcelo J

            Comment


              #7
              Re: Macbook Core i7 2010 a1286 820 - 2850A CRAZY JUMPING voltages

              My question is: Given that f7040 removed is having steady 12.35v one side, but when i solder back I have a slight variation between 12.4v to 12.48, but all dependant lines have a more crazy variations like PP3V3_S5 = 0v to 3.33 v jumping, the question is how can i isolate the other parts or when to inject volts..red lines in this picture

              Marcelo J

              Comment


                #8
                Re: Macbook Core i7 2010 a1286 820 - 2850A CRAZY JUMPING voltages

                Current sense resistors are ok (the 4 ones) in U7000 area, 10ohm, 0 ohm and 2.2ohm ...
                Marcelo J

                Comment


                  #9
                  Re: Macbook Core i7 2010 a1286 820 - 2850A CRAZY JUMPING voltages

                  i have been lifting up coils and testing volt /mah variation in my power supply and L7260 was the cause of jumping...when that on removed (one leg) I can see steady output,,,,,, so i will put it back that coil and check what might be wrong in that area, which is the 3,3 and 5v power supply....

                  SO i think I have somethjing wrong with 3.3v , need to know if load side or ic source side.... the ohms each side of L7260 are: pin 1 lifted = 4.5kohm (red on ground resistance mode) and pin 2 = 11kohm
                  Last edited by marce002; 09-10-2021, 06:44 AM.
                  Marcelo J

                  Comment


                    #10
                    Re: Macbook Core i7 2010 a1286 820 - 2850A CRAZY JUMPING voltages

                    ok it is on!!!!! with chan sound and also image!!!!! after some debugging and heatings to the board while inspecting derived loads from PP3V3_S5.... full speed fans though an quite slow.....

                    closed
                    Marcelo J

                    Comment

                    Working...
                    X