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A1708 820-00840-A 5V 80-100mA

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    #1

    A1708 820-00840-A 5V 80-100mA

    Hi all!
    I´m new troubleshooting MacBooks and I need a little help. I have A1708 13" Macbook Pro stuck in 5v 27-33mA. Sometimes go up to 50mA and then back to 30mA. Also sometimes go down to 0mA and restart the cycle again(27-33mA). I have checked all the voltages in U3200 (https://logi.wiki/index.php/CD3215_Bootup_Sequence) and the only one that is missing is PP1V1_UPC_XB_LDO_BMC. The G3H rails that I have are cycling. No PPBUS_G3H. What should I do next? THANK YOU FOR HELPING ME!
    Last edited by Aitorflores7; 01-29-2022, 08:18 AM.
    Tags: None
    #2
    Re: A1708 820-00840-A 5V 80-100mA

    Hello, do you have PP3v3 G3Hot?

    Comment

      #3
      Re: A1708 820-00840-A 5V 80-100mA

      Hello! Yes, I have pp3v3_g3h

      Comment

        #4
        Re: A1708 820-00840-A 5V 80-100mA

        pp3v3_g3h rail and other g3h rails are cycling

        Comment

          #5
          Re: A1708 820-00840-A 5V 80-100mA

          Interesting! Is PM_EN_P3V3_G3H_R cycling too?

          Comment

            #6
            Re: A1708 820-00840-A 5V 80-100mA

            And check PPDCIN_G3H_CHGR if it is cycling too. Try to test on the two USB-C ports and see if on both you have 5V and the same amp draw

            Comment

              #7
              Re: A1708 820-00840-A 5V 80-100mA

              Yes, PM_EN_P3V3_G3H_R and PPDCIN_G3H_CHGR are cycling too. I compare the 2 usb-c ports and the amp draw is the same, they are doing the same cycle i mentioned in the first post

              Comment

                #8
                Re: A1708 820-00840-A 5V 80-100mA

                I think there might be a problem on a G3H rail, test ALL the G3H rails and check for shorts (I had a similar amp draw one time on this board it was a short on a G3Hot rail). It coulmd also be a sensor issue around the ISL, so check resistors around the ISL9239 and also caps for shorts.

                Comment

                  #9
                  Re: A1708 820-00840-A 5V 80-100mA

                  Place your meter in resistance mode (2k). Remove all power. Check for any low resistance to ground on each and every coil on the logic board. Looking for any low resistance reading which may indicate a shorting cap = excessive current draw = power cycling to make it safe (chirp mode).

                  Comment

                    #10
                    Re: A1708 820-00840-A 5V 80-100mA

                    Originally posted by Win Me View Post
                    I think there might be a problem on a G3H rail, test ALL the G3H rails and check for shorts (I had a similar amp draw one time on this board it was a short on a G3Hot rail). It coulmd also be a sensor issue around the ISL, so check resistors around the ISL9239 and also caps for shorts.
                    Could you tell me what g3h rails do i have to check? maybe im missing someone. I chech everything around isl9239 and no shorts found. Also the resistors i think they are reading ok. Do i have to post any readings?

                    Comment

                      #11
                      Re: A1708 820-00840-A 5V 80-100mA

                      Originally posted by mon2 View Post
                      Place your meter in resistance mode (2k). Remove all power. Check for any low resistance to ground on each and every coil on the logic board. Looking for any low resistance reading which may indicate a shorting cap = excessive current draw = power cycling to make it safe (chirp mode).
                      I think i have check all coils of the board, but im not sure. Some coils have low ohm readng due to are connected to the cpu, am i right?

                      Comment

                        #12
                        Re: A1708 820-00840-A 5V 80-100mA

                        On the schematic you have a list of all the power rails, if there is G3Hot in the name of the rail test it. Yes Coils around the CPU have a low resistance to ground. Place a probe point on PPBUS_G3_HOT and the other on coils around the CPU, if you see no resistance it is probably a dead CPU

                        Comment

                          #13
                          Re: A1708 820-00840-A 5V 80-100mA

                          You said some rails are cycling, does the amp meter is cycling too?

                          Comment

                            #14
                            Re: A1708 820-00840-A 5V 80-100mA

                            Originally posted by Win Me View Post
                            On the schematic you have a list of all the power rails, if there is G3Hot in the name of the rail test it. Yes Coils around the CPU have a low resistance to ground. Place a probe point on PPBUS_G3_HOT and the other on coils around the CPU, if you see no resistance it is probably a dead CPU
                            I have tested now all the G3Hot rails and no shorts. Between ppbus and cpu coils 1,2Mohms

                            Comment

                              #15
                              Re: A1708 820-00840-A 5V 80-100mA

                              Originally posted by Win Me View Post
                              You said some rails are cycling, does the amp meter is cycling too?
                              No, is what surprises me. The amp meter stays on and only changes the amp draw.

                              Comment

                                #16
                                Re: A1708 820-00840-A 5V 80-100mA

                                Well, I would most likely think of a CD3215 issue or an ISL9239 issue. It could be a Thunderbolt ROM issue, but with a 50 amp draw I doubt. If only one of the two CD3215 fail then the other one will not work

                                Comment

                                  #17
                                  Re: A1708 820-00840-A 5V 80-100mA

                                  Have you also check the board visualy, Try to see if there are not any corrosion, cracks on capacitors, burn marks, etc

                                  Comment

                                    #18
                                    Re: A1708 820-00840-A 5V 80-100mA

                                    Originally posted by Win Me View Post
                                    Have you also check the board visualy, Try to see if there are not any corrosion, cracks on capacitors, burn marks, etc
                                    The board is super clean. No dust,no corrosion...

                                    Comment

                                      #19
                                      Re: A1708 820-00840-A 5V 80-100mA

                                      Originally posted by Win Me View Post
                                      Well, I would most likely think of a CD3215 issue or an ISL9239 issue. It could be a Thunderbolt ROM issue, but with a 50 amp draw I doubt. If only one of the two CD3215 fail then the other one will not work
                                      So im going to buy some cd3215 and check if that solve the problem. If i remove the two cd3215, rails should stop cycling?

                                      Comment

                                        #20
                                        Re: A1708 820-00840-A 5V 80-100mA

                                        If you remove them you will get nothing, maybe try to remove R7020 and D6905 first and see if it is still cycling. If still most likely the CD3215, if not the probably an ISL related issue

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