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Macbook 820-3115 missing 3V42_G3H

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    #21
    Re: Macbook 820-3115 missing 3V42_G3H

    Good.

    Resistance to GND on L6995 (PP3V42_G3H_REG) ?

    Comment


      #22
      Re: Macbook 820-3115 missing 3V42_G3H

      Pin 2 on L6995 is someting about 135kohms, L6995 is still removed from the board.

      Comment


        #23
        Re: Macbook 820-3115 missing 3V42_G3H

        That is a much better resistance than before. If the other side of L6995 is also a high reading, then proceed to solder back L6995 so that it can perform its job.

        The voltage output of L6995 should be ~3v42 if all is well on this rail.

        Comment


          #24
          Re: Macbook 820-3115 missing 3V42_G3H

          The other side is reading O.L,
          so should be good i guess.

          Comment


            #25
            Re: Macbook 820-3115 missing 3V42_G3H

            Both Pins on L6995 are around 125k ohms now that L6995 is soldered back.
            Is it safe now to plug in the magsafe connector?

            Comment


              #26
              Re: Macbook 820-3115 missing 3V42_G3H

              I think it is. Do measure the output of the L6995 and it should be ~3v42 if all is well.

              Comment


                #27
                Re: Macbook 820-3115 missing 3V42_G3H

                Still reading nothing on L6995 and U6990 isn´t producing PP3V42_G3H.
                Last edited by Nuld_; 06-24-2022, 12:13 PM.

                Comment


                  #28
                  Re: Macbook 820-3115 missing 3V42_G3H

                  And U7941 is now shorting again on Pin 1.

                  Comment


                    #29
                    Re: Macbook 820-3115 missing 3V42_G3H

                    Confirm the input voltage to U6990, pin # 7 - measure @ D6990, pin # 3 (PPVIN_G3H_P3V42G3H).

                    Comment


                      #30
                      Re: Macbook 820-3115 missing 3V42_G3H

                      Pin 7 is reading 16,6V and Pin 3 is at 15,1V.

                      Comment


                        #31
                        Re: Macbook 820-3115 missing 3V42_G3H

                        Are you using an official magsafe adapter ?

                        Remove all power, check the resistance to ground of L6995, pin #2. Be sure that L6995 inductor is soldered in properly and mating with the PCB pads.

                        Comment


                          #32
                          Re: Macbook 820-3115 missing 3V42_G3H

                          It reads around 3 ohms again. I guess it fried the U7941 again.

                          It´s not a official magsafe adapter but it worked with the samelogicboard in the past.
                          Last edited by Nuld_; 06-24-2022, 01:15 PM.

                          Comment


                            #33
                            Re: Macbook 820-3115 missing 3V42_G3H

                            I would buy a Costco lot of U7941 devices from Aliexpress. Do ask if they are valid for macbook repairs but believe this is a fixed function device that should just operate as expected upon soldering. Silego has many programmable devices and you need special tools and IP to configure them otherwise.

                            Remove all power and check the resistance to ground of the 3 x outputs of this device (pin 4, 3 and 8).

                            What are the readings ?

                            Comment


                              #34
                              Re: Macbook 820-3115 missing 3V42_G3H

                              Pin 4 is at 15Mohms, Pin 3 is at 15,6Mohms and Pin 8 is at 15,6Mohms aswell.

                              Comment


                                #35
                                Re: Macbook 820-3115 missing 3V42_G3H

                                The resistance is ok.

                                Very strange, yet this part dies.

                                What are the resistance readings to ground for the input pins 2, 6, 7 ?

                                Would not be a bad idea to source & replace U6990 (PM6640). If nothing else, you will have spare parts for future repairs.

                                Comment


                                  #36
                                  Re: Macbook 820-3115 missing 3V42_G3H

                                  Readings on U7941 are:
                                  Pin 1: 2,6 ohms
                                  Pin 2: 16.1 Mohms
                                  Pin 3: 16 Mohms
                                  Pin 4: 16 Mohms
                                  Pin 5: 2,5 ohms
                                  Pin 6: 676 ohms
                                  Pin 7: O.L
                                  Pin 8: 16 Mohms

                                  Readings on U6990:
                                  Pin 1: 1,2 Mohms
                                  Pin 2: O.L
                                  Pin 3: something around 2Mohms
                                  Pin 4: something around 2,2 Mohms
                                  Pin 5: 0,3 ohms
                                  Pin 6: 2,9 ohms
                                  Pin 7: something around 2,2 Mohms
                                  Pin 8: O.L
                                  Pin 9: 2,4 ohms
                                  Pin 10: 167k ohms

                                  Comment


                                    #37
                                    Re: Macbook 820-3115 missing 3V42_G3H

                                    Remove U7941 off the board.

                                    Does the low resistance disappear @ L6995, pin # 2 ?

                                    If yes, power up (without U7941) and confirm if the voltage @ L6995, pin # 2 = +3v42.

                                    Comment


                                      #38
                                      Re: Macbook 820-3115 missing 3V42_G3H

                                      Pin 2 of L6995 is reading 130,5k ohms
                                      Voltage is reading 0V.

                                      Comment


                                        #39
                                        Re: Macbook 820-3115 missing 3V42_G3H

                                        Uhm, now Greenlight is on with 3,4V on Pin 2 of L6995 without U7491 even attached.
                                        And U7200 is getting hot too.
                                        Last edited by Nuld_; 06-25-2022, 11:34 AM.

                                        Comment


                                          #40
                                          Re: Macbook 820-3115 missing 3V42_G3H

                                          U7200 Ohm Readings:
                                          Pin 1: 115k
                                          Pin 2: 8,32k
                                          Pin 3: 383k
                                          Pin 4: 1M
                                          Pin 5: 3,92k
                                          Pin 6: 78,6k
                                          Pin 7: 3,1
                                          Pin 8: 1M
                                          Pin 9: O.L
                                          Pin 10: 43,4
                                          Pin 11: 3
                                          Pin 12: 106,5 k
                                          Pin 13: O.L
                                          Pin 14: 382k
                                          Pin 15: 0
                                          Pin 16: 4,5
                                          Pin 17: 37,5
                                          Pin 18: 800
                                          Pin 19: 106,7k
                                          Pin 20: 6,4
                                          Pin 21: 106k
                                          Pin 22: O.L
                                          Pin 23: 10k
                                          Pin 24: 6,2

                                          Comment

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