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MBP 820-3787 no green light

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    MBP 820-3787 no green light

    Hi,

    first a little history on this board. It was working over night connected to charger and died, no green light. First it seemed an easy job, sense resistors on U7100 were measuring milion ohms... replaced that and U7100, worked till first restart, then i got it working again.. and it went out again.

    I have replaced U7100, Q7130, Q7135, Q7180 two times, ran wire R7121 to pin 4 R7120. Replaced SMC twice. Checked all connections around U7100 and all resistors are ok, also there are no shorts.Removed F7140/41. No green light.


    PP3V42_G3H is 3,39V , is that enough? Should be 3,42v, but U7090 is ok, R7095/96 ok.

    PPBUS_G3H 1,78V
    CHGR_DCIN 20V
    CHGR_PHASE 1,78V
    CHGR_LGATE 0V
    PPDCIN_G3H_CHGR 1,78v

    These are values as i remember them, can check it again tomorrow.

    Any suggestion would be helpful.

    Thank you!

    #2
    Re: MBP 820-3787 no green light

    Liquid damage? Knockoff Magsafe or battery? Tried another known good Magsafe2 85W?
    OpenBoardView — https://github.com/OpenBoardView/OpenBoardView

    Comment


      #3
      Re: MBP 820-3787 no green light

      No liquid damage. It was used with non-original charger, probably that caused it. Battery still original. Board itself was pristine, nothing burned. Yes, tried two original 85W chargers.
      Last edited by daltonjr.; 04-01-2020, 04:25 PM.

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        #4
        Re: MBP 820-3787 no green light

        hello, without green light, it wont turn on PPBUS_G3H.

        the more u work on a model, more u can make trouble.

        post voltage of : u7000, u7001

        Comment


          #5
          Re: MBP 820-3787 no green light

          I know, its frustrating...

          SMC_BC_ACOK 0v
          PP3V42_G3H is 3,39V

          SMC_BC_ACOK_VCC 0v
          SYS_ONEWIRE 0v

          Have checked continuity between all these lines and smc, all good. U7000/U7001 replaced, also good.

          I dont remember about ADAPTER_SENCE, not currently at the bench.

          Comment


            #6
            Re: MBP 820-3787 no green light

            post all u7100 pin voltage. be carefull when measuring.

            without psu check u7100 pin 27 pin 28 (one probe pin 27 other probe pin 28) is 20 omh otherwise measure omh of r7121 r7122 they have to be 10 omh
            Last edited by dellxps15; 04-02-2020, 07:50 AM.

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              #7
              Re: MBP 820-3787 no green light

              27/28 is around 20ohms and 17/18 around 2,5ohms. I will measure all U7100 pins tomorrow as i get home. Thanks

              Comment


                #8
                Re: MBP 820-3787 no green light

                hello
                since this happens with non official charger try with a good one I/O board, without green light you can't do nothing and explore on your macbook

                first you have to get PP3V42 one onewire circuit. since u don't have it u will get nothing more.
                the onewire circuit is an independant circuit so first u have to get green light.

                so :
                1) use correct charger
                2) with know good I/O board
                and then u'll can test the rest og onewire circuit

                Comment


                  #9
                  Re: MBP 820-3787 no green light

                  Doesnt ONEWIRE require SMC_BC_ACOK_VCC to work?, that comes from SMC.

                  I tried 2 original chargers. (I have meant, that this damage happened on non-original charger that the owner had)

                  I will try another know good I/O, although i tried two.. but you never know.

                  Hopefully i get back tomorrow with some good news Thanks all

                  Comment


                    #10
                    Re: MBP 820-3787 no green light

                    Originally posted by daltonjr. View Post
                    I know, its frustrating...

                    SMC_BC_ACOK 0v
                    PP3V42_G3H is 3,39V

                    SMC_BC_ACOK_VCC 0v
                    SYS_ONEWIRE 0v

                    Have checked continuity between all these lines and smc, all good. U7000/U7001 replaced, also good.

                    I dont remember about ADAPTER_SENCE, not currently at the bench.
                    SMC_BC_ACOK 0V then you need to replace your ISL6259 chip

                    Comment


                      #11
                      Re: MBP 820-3787 no green light

                      Yesterday i got back to this one and got some progress. I found knocked off resistor around SMC and broken trace from R7152 to R7150. Replaced Q7130/Q7135 and ISL from a known good board. I have green light, PPBUS_G3H 12,63V. I have done some measurement around Q7130/Q7135... and i see that CHGR_LGATE is fluctuating from 0,6 to 0,9V. I have measured it on a other board, it is steady 0,87V. Macbook boots, but cuts off power after few seconds, not always at the same time. Must still be something wrong around that power circuit. Maybe some bad capacitor somewhere.. ?

                      Comment


                        #12
                        Re: MBP 820-3787 no green light

                        Found out that it didnt charge battery. Replaced Q7155, now its working. Will test it for a couple of days. Hope this is it.

                        Comment


                          #13
                          Re: MBP 820-3787 no green light

                          +1

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