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Macbook A1706 EMC3071 (2017 Touchbar)

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    #41
    Re: Macbook A1706 EMC3071 (2017 Touchbar)

    Apply flux onto the PCB pads and solder back the removed U6903 IC.

    After a proper heating of this part (go in circles) - the IC will just swim and settle back onto the PCB pads, naturally. Then remove your heat.

    After cooling down this site (wait a few minutes) -> check the resistance to ground again of this pin # 3 of the dual diode. The resistance should remain high.

    Repeat with the other removed caps. If the resistance falls to the very low level, then that part is defective and needs to be replaced or kept off the board.

    Do note the pin # 1 location (dot) on the U6903 IC for placement.

    Comment


      #42
      Re: Macbook A1706 EMC3071 (2017 Touchbar)

      I solder back the IC and diode. I have 5.5mohm on pad #3.
      I connect the USB charger and now, i have on pin #2 : 5.12V and pin #3 : 3.58V.
      On pin #1, i don't know if it's normal but i find -0.05V...
      C6906, C6905 and C7081 are removed.
      On my USB tester, the board doesn't drain anything.

      Comment


        #43
        Re: Macbook A1706 EMC3071 (2017 Touchbar)

        It is best to only solder back a single component at a time as we do not know yet, how many parts are defective in this region of the logic board.

        The earlier post mentioned ~72k resistance to ground. That is a good reading.

        Meter probe should be to the point to test; other meter probe to ground.

        After soldering back the IC, the reading is:
        I have 5.5mohm on pad #3.
        Suggest to remove the diode and confirm that the IC (only) is not tanking this line down to a dangerous level for the resistance.

        On your meter, what is the scale ? There should be no power on the logic board at this time.

        Is the reading 5.5 Mohm ? (~5.5 megaohms?) Still a good reading if high but surprised it is so high since you have 72k from before. Confirm it again.

        Then introduce the diode and check the resistance again at this pin # 3 junction of the dual diode.

        Pin #1 on the diode is normal since the voltage @ U7000 is not being created properly at this time.

        Pin # 2 is ok since it is fed from the external adapter which is ~5 volts.

        The voltage @ pin # 3 of this dual diode is not ok - it is a drastic drop and should only be about 0v6 lower than the input on pin # 1 of # 2 (whichever is the higher voltage).

        Only once this pin # 3 voltage is correct will the U6903 do its job to offer the 3v3 as the output.

        It is possible that U6903 is defective and needs to be replaced but we still need to do some checks - specifically, why is the output of this dual diode so low ? It is too low to turn ON the U6903 regulator.

        Comment


          #44
          Re: Macbook A1706 EMC3071 (2017 Touchbar)

          I remove the diode and i take the resistance on this famous Pad #3 : the resistance gradually increases from about 50 mohm to OL.

          We agree on the measurements: I place the black probe on ground and the red on pad #3, right?

          Comment


            #45
            Re: Macbook A1706 EMC3071 (2017 Touchbar)

            The polarity of the meter leads will not matter when in resistance mode.

            Can you confirm the details of the replacement dual diode ? From where did you source this part ?

            Also, with your meter in DIODE mode, check that the diode is a common cathode style. That is, the topside of the 'arrow head' in the schematic are tied together.

            Based on this assumption, test as follows (while the diode is off the board):

            red meter lead to the backside (side with the 2 legs) of the diode; black meter lead to the single pin (aka pin # 3) -> meter should conduct and offer a reading.

            Reverse the leads, and the meter should be OL.

            Then do the same with the pin # 1 of this dual diode.

            If you have any other reading, then this diode is not suitable or is defective.

            Concerned about the large voltage drop from input to output of this diode.

            Comment


              #46
              Re: Macbook A1706 EMC3071 (2017 Touchbar)

              The diode come from a donor board, an old macbook Pro.

              The diode seems to be burned again... I have nothing on test with pin #2 and #3 . With the pin #1, it's ok. I have a value on a side and OL in other.

              I'll buy diodes if i find it quickly but it's the third diode who burned after soldering. Strange no ?
              Thank you very much

              Comment


                #47
                Re: Macbook A1706 EMC3071 (2017 Touchbar)

                100% recommend to buy spare diodes, they are inexpensive.

                100% recommend to buy spare U6903 regulators - cheap on Aliexpress.

                Try the following approach,

                1) desolder the defective dual diode & U6903 regulator.

                2) solder in only a fresh dual diode -> confirm the voltage passes through onto pin # 3 with little voltage drop. This is import to confirm. If the voltage drop is too much or diode burns out then some other fault on this line.

                3) After the above confirmation, proceed to solder down a fresh U6903. Test again and the voltage on pin #3 should remain higher than reported.

                Comment


                  #48
                  Re: Macbook A1706 EMC3071 (2017 Touchbar)

                  Hello,

                  Thank you very much for all. I order diode and the IC. I'll come back here after receive them.
                  Have a nice day.

                  Comment


                    #49
                    Re: Macbook A1706 EMC3071 (2017 Touchbar)

                    Hello,
                    I don't leave the thread I'm waiting after spares. Normaly i'll receive it in few days.
                    Thank you

                    Comment


                      #50
                      Re: Macbook A1706 EMC3071 (2017 Touchbar)

                      Hello,

                      Can you tell me if this one is the good spare please? I never receive the package from Aliexpress... :
                      https://www.mouser.fr/ProductDetail/...oKZrjsfQ%3D%3D

                      Thank you very much !

                      Comment


                        #51
                        Re: Macbook A1706 EMC3071 (2017 Touchbar)

                        Which part was ordered from AliExpress? When was it ordered? Which level of shipping was selected?

                        Be patient, the part will arrive from China but often it is slow in transit if a free shipping method was selected. Contact the vendor for assistance.

                        Which part do you wish to order from Mouser? Many parts are only available through AliExpress or a donor board of the original.

                        Comment


                          #52
                          Re: Macbook A1706 EMC3071 (2017 Touchbar)

                          I received the diodes but the U9080 never arrived. I am in dispute with the seller.
                          I will not receive it from him. To go faster, I saw that Mouser offered this component under its reference but I'm not sure if it is the same.
                          Thanks to you

                          Comment


                            #53
                            Re: Macbook A1706 EMC3071 (2017 Touchbar)

                            I am unable to locate U9080 on the A1706 schematic.

                            Did find U9080 on A1990 (820-01041) logic board.

                            Can you confirm which logic board you are currently servicing? If on A1990 unit, yes the posted link from Mouser should be fine.

                            You can also source these from Digikey:

                            https://www.findchips.com/search/tps62180yzfr
                            * for us in Canada, Digikey is able to ship at a lower cost than Mouser

                            https://www.digikey.ca/en/products/d...ampaign=buynow
                            * currency is USD

                            Comment


                              #54
                              Re: Macbook A1706 EMC3071 (2017 Touchbar)

                              The A9080 is the same spare as the U6903 if i trust in Aliexpress (https://fr.aliexpress.com/item/10050...yAdapt=glo2fra)
                              If the item is the same, i'll order it on Mouser or Digikey
                              Thanks again.

                              Comment


                                #55
                                Re: Macbook A1706 EMC3071 (2017 Touchbar)

                                Can you clarify again the logic board and part you wish to purchase from Mouser / Digikey?

                                Is it for the 3v42 rail repair = U6903 on 820-00239 board?

                                We want to be 100% sure before you proceed.

                                See attached. If it is for this replacement - the part is not the same. This is the maxim MAX77596. The package is a DFN package instead of BGA (WLCSP). Very different parts.

                                The Aliexpress link is not correct for this servicing of your A1706 logic board.

                                You need this one:

                                https://fr.aliexpress.com/item/40000...850015497985_2

                                *request that you only need 2-3 pcs for the repair

                                Be sure to copy the reference with the vendor before ordering. Do note the exact U6903 and the A1706 logic board and you will be fine.

                                These are vendors we use all the time without issues on Aliexpress.
                                Attached Files
                                Last edited by mon2; 10-07-2022, 05:31 AM.

                                Comment


                                  #56
                                  Re: Macbook A1706 EMC3071 (2017 Touchbar)

                                  I'm taking about the U6903 on boardview. You asked me for replace it (and the diode). I have diodes but not this spare. Is it a MAX77596 ?
                                  Attached Files

                                  Comment


                                    #57
                                    Re: Macbook A1706 EMC3071 (2017 Touchbar)

                                    Correct.

                                    U6903 = MAX77596 (TDFN package).

                                    So my last link on Aliexpress is correct. This part is responsible to create the PP3V3_G3H voltage rail on the logic board.
                                    Attached Files

                                    Comment


                                      #58
                                      Re: Macbook A1706 EMC3071 (2017 Touchbar)

                                      Hi Mon2,

                                      I just receive the package from Aliexpress... So long.
                                      Anyway, i replace the U6903 and the diode but nothing happen when i connect the charger. 0V 0A.
                                      Are you ok to continue with my case ? Thank you very much

                                      Comment


                                        #59
                                        Re: Macbook A1706 EMC3071 (2017 Touchbar)

                                        Remove all power. Meter in resistance mode.

                                        Check the resistance to ground of each pin on the diode D6902.

                                        Then the resistance to ground of the coil at U6903. Post each measurement.

                                        If any of the resistance is low, there is a short on the line that must be located and repaired.

                                        If the resistance checks are not low, power up and with the meter in DC volts mode (20v or higher), check the voltage to ground on each pin of the same diode at D6902.

                                        Also measure the voltage to ground at the output coil of U6903.

                                        Post each voltage measurement.

                                        Comment


                                          #60
                                          Re: Macbook A1706 EMC3071 (2017 Touchbar)

                                          I'm glad to see you are always here after all this days. THank you !

                                          So, i check the diode D6903 : Pin 1 = 26 mOhm, Pin 2 = upscale from 10k to more than 230kohm and Pin 3 : 4.30mOhm.

                                          I can't check on the U... My probe are too big for check directly between the spare and the cap under it.

                                          Comment

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