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    macbook a2141 board 820-1700 no turn on

    hi , i am denis

    ok so this is my first repair and i am also new to the terminology , now thats out the way..

    2019 a2141 16 inch t2 board 820-01700

    ok i have 5.2vdc .0ma on usb c ameter

    on the board i get 5vdc on f3000 & f3001

    any help would be appreciated

    regards

    den
    Last edited by dcs10; 10-09-2021, 01:19 PM.

    #2
    Re: macbook a2141 board 820-1700 no turn on

    Hi. Would you know the history of this logic board?

    Any visible liquid damage?

    Apple uses dot stickers that will turn red when triggered by liquid. Do you see any red dots on the logic board?

    Comment


      #3
      Re: macbook a2141 board 820-1700 no turn on

      hi ,no liquid damage as fair as i can see . board personal


      f3000/f3001 5vdc

      pp3v3_upc_xb_ldo 3.4vdc

      pp1v5_upc_xb_ldo_core 1.5vdc

      pp3v3_g3h_rtc_x 0.27mv

      pin 1 c3500 ppbus_g3h 118mv

      all voltages around u3200

      regards

      den
      Last edited by dcs10; 10-09-2021, 08:53 PM.

      Comment


        #4
        Re: macbook a2141 board 820-1700 no turn on

        1) voltage at L3500, pin 2?

        2) if not normal voltage, remove all power meter in resistance mode. Red meter lead on L3500, pin 2 and black lead to ground.

        Resistance reading?

        3) when power is applied to the logic board, voltage

        @ PPBUS_G3H ?

        @ PP5V_G3S ?

        @ UPC_X_5V_EN_R ?

        @ PP5V_S4_X_USBC ?

        @ PP3V3_S5 ?

        4) your power adapter is a known good unit? Compatible to support the required current for this logic board?

        Comment


          #5
          Re: macbook a2141 board 820-1700 no turn on

          L3500, pin 2 000.5mvdc

          L3500, pin 2 resistance 0 ohms

          PPBUS_G3H .200mv

          PP5V_G3S 24mv

          UPC_X_5V_EN_R 0v

          PP5V_S4_X_USBC .800 mv

          PP3V3_S5 0v


          ok did it

          power adapter is a good unit, and Compatible to support the required current for this logic board


          regards

          den

          Comment


            #6
            Re: macbook a2141 board 820-1700 no turn on

            ok.

            1) PP5V_G3S is a critical rail to power many devices onboard. This rail is not working or is being told to remain off.

            2) Post the voltage of:

            PPBUS_HS_3V3G3H_T

            P5VG3S_EN_R


            P3V3G3H_EN


            PP5V_S5_LDO


            PP3V3_G3H_T


            3) Remove all power. Meter in resistance mode.

            Resistance to ground of inductor (coil) L7660, pin 1 ?

            Resistance to ground of inductor (coil) L7600, pin 1 ?

            4) Confirm again that resistance at L3500, pin #2 is 0 ohms. If true and resistance is this low then this implies there is a short circuit on this rail.

            At this time, we do not know if the short is on the LEFT side (voltage PRODUCER) of L3500 (with respect to how the schematic is drawn) or to the RIGHT side of L3500 (voltage CONSUMER).

            If you have hot air tools, consider to desolder and lift up one side of L3500. This may require some high heat to melt. Do not power up with the L3500 removed (to be safe).

            Once one leg is lifted on L3500, check the resistance to ground once again at pad # 2 of L3500.

            What is the resistance value with L3500 removed ? If the resistance is no longer zero, then we know that the short is on the LEFT side of this power supply circuit. If the resistance is still zero ohms then we know the issue is with the RIGHT side of this power rail.

            It is interesting to note that this rail generates PP5V_S4_X_USBC which is the Vbus power rail for one of your USB Type C connectors. This connector pin is also almost 0 volts where it should have been 5v.

            This rail powers one of the ACE controllers (@U3100) which negotiates the power delivery contracts with your mated Type C adapter. As per logiwiki website, BOTH of the ACE controllers on your laptop must operate correctly else the power delivery contracts cannot negotiate to dial up the desired 20v to run your logic board.

            Interested to know of the resistance reading without L3500 in the circuit so we can home in on the section of the board that needs immediate attention. My spidey sense is thinking one of the bulk caps is shorted and it may very well be C3505 - C3506 - C3507 - C3508 range. More on this after your results are posted.
            Attached Files

            Comment


              #7
              Re: macbook a2141 board 820-1700 no turn on

              thank you very much , i will try and do what you have ask post asap

              regards

              den

              Comment


                #8
                Re: macbook a2141 board 820-1700 no turn on

                hi mon2,



                l3500 is short circuit


                can i Power the circuit without the inductor in ?

                regards

                den

                Comment


                  #9
                  Re: macbook a2141 board 820-1700 no turn on

                  hi. Can you clarify the details of L3500 ?

                  You have lifted one of the legs of L3500?

                  After this lift, which pad on L3500 is still shorted (0 ohms) ?

                  Is it pin # 1 or pin # 2 of L3500 ?

                  If pin # 1 (ie. LEFT side of the schematic) = 0 ohms, then we need to review the DUAL MOSFET @ Q3501.

                  For completion, can you also post the resistance to ground on pad # 2 after the coil is lifted ? It should now certainly be higher than 0 ohms.

                  Next, need to investigate the resistance on all legs of Q3501 as follows.

                  Q3501 is a single packaged component that features 2 * mosfets inside. These are transistors that can switch on / off very rapidly and are meant to handle heavy currents.

                  Meter in still resistance mode. All power removed (ie. no adapter & no battery).

                  Q3501 -

                  Post the resistance between 8-9 (Drain) & 2-3-4 (Source).

                  Post the resistance between 8-9 (Drain) & pin 1 (Gate).

                  Post the resistance between pin 1 (Gate) & 2-3-4 (source).

                  The above is for the internal HIGH SIDE MOSFET.

                  Next, need to measure the resistance of the LOW SIDE MOSFET. Guessing there is a short on the low side but let us see.

                  Post the resistance between 2-3-4 (Drain) & 5-6-10 (Source).

                  Post the resistance between 2-3-4 (Drain) & pin 7 (Gate).

                  Post the resistance between pin 7 (Gate) & 5-6-10 (source).

                  The above is for the internal LOW SIDE MOSFET.

                  Do not turn on the logic board with the adapter with L3500 lifted as there is no point till we can locate the root cause(s).

                  If Q3501 is indeed defective, the part is from ONSEMI (datasheet is attached).

                  https://www.aliexpress.com/wholesale...psort=1&page=1
                  Attached Files

                  Comment


                    #10
                    Re: macbook a2141 board 820-1700 no turn on

                    Resistance to ground of inductor (coil) L7660, pin 1 00.04

                    Resistance to ground of inductor (coil) L7600, pin 1 00.04

                    L3500 is still shorted (0 ohms)

                    regards

                    den

                    Comment


                      #11
                      Re: macbook a2141 board 820-1700 no turn on

                      pin # 1 pad to ground of L3500 32 kohms

                      pin # 2 pad to ground of L3500 is 36 kohms

                      will start tomorrow on Q3501


                      cheers again

                      den

                      Comment


                        #12
                        Re: macbook a2141 board 820-1700 no turn on

                        If you are measuring the resistance between pins 1 & 2 of the coil, then yes, the resistance will be 0 ohms as this is only a bunch of magnet wire across the 2 pads.

                        Please confirm the details of how the 0 ohms was measured.

                        If across pins 1 & 2 then no reason to check the mosfets as the resistance to ground is ok from your posted values.

                        Instead, need to check the other requested voltages for this ic.

                        The 2nd ace controller must function to allow for the 20v to be selected from your external adapter.

                        Comment


                          #13
                          Re: macbook a2141 board 820-1700 no turn on

                          inductor measured out of circuit

                          den

                          Comment


                            #14
                            Re: macbook a2141 board 820-1700 no turn on

                            The inductor is treated just like a wire with respect to the resistance across the 2 terminals. The resistance @ 0 ohms for this component is correct.

                            If the solder pads on the logic board for this part are 0 ohms to ground then there is a short on some component on this rail. You have much higher resistance on the inductor pads which is a good reading.

                            You can solder this inductor back onto the board. The issue is elsewhere.

                            Do post the other requested measurements.

                            Comment


                              #15
                              Re: macbook a2141 board 820-1700 no turn on

                              hi

                              am i following you ? which ic is the 2nd ace controller is it U3200?

                              what rails would you like me to measure


                              that inductor L3500 got damaged the leg got riPPed off

                              sad


                              regards

                              den
                              Last edited by dcs10; 10-11-2021, 02:02 PM.

                              Comment


                                #16
                                Re: macbook a2141 board 820-1700 no turn on

                                Attaching the specs for L3500. It should be possible to source a valid replacement with similar or better specs in the same PCB footprint.

                                Review the height of this component (2.4mm) with respect to where it is sitting on the logic board.

                                The following (4.8mm height) should work fine to replace the original. Just confirm that the extra 2.4mm height will not be a factor.

                                Bourns p/n SRP7050AA-1R5M

                                https://www.newark.com/bourns/srp705...ed/dp/32AJ8865
                                * stock in the UK

                                Link to datasheet for the replacement inductor:

                                https://cdn.badcaps-static.com/pdfs/...6a5b2a6b54.pdf


                                If height is critical, then consider (3.0 mm height):

                                https://cdn.badcaps-static.com/pdfs/...6a4f190ccf.pdf

                                p/n MND-07CZI1R5M-XB-RU

                                Available through Digikey.
                                Attached Files
                                Last edited by mon2; 10-11-2021, 03:27 PM.

                                Comment


                                  #17
                                  Re: macbook a2141 board 820-1700 no turn on

                                  cheers thanks again

                                  what is the 2nd ace controller?


                                  regards

                                  den

                                  Comment


                                    #18
                                    Re: macbook a2141 board 820-1700 no turn on

                                    can i still apply power to the logic board, so i can measure around the 2nd ace controller without the l3500 inci

                                    Comment


                                      #19
                                      Re: macbook a2141 board 820-1700 no turn on

                                      See attached.

                                      Each USB Type C connector has its own, local 'ACE' controller. This controller is effectively a stand-alone IC (made by Texas Instruments for Apple and private labelled for them to their specs but is similar to other parts from TI for us mortals).

                                      Provided that the ACE controller is functioning, it is able to negotiate with the mated power adapter (USB Type C) using Power Delivery hand-shakes.

                                      In summary, the power adapter (power provider) broadcasts a list of power contracts to the power consumer (the logic board). The ACE controller then decides on the best contract to move forward which on your box is currently @ 5v0 (rather than 20V).

                                      There are tools that can offer a snooping feature to view the contracts being exchanged. The USB meters show the end result of the hand shake. The 5v0 is always default even if the hand shake fails.

                                      Based on the (attached partial) schematic, there are 4 * ACE controllers so your box must have 4 * Type C ports on the logic board ?

                                      On this note, take it that you have tested other ports on this logic board to power the box ?

                                      Perhaps you can check for any physical damage near these controllers and be sure that the USB Type C connectors are properly seated. Often Apple will use small daughter paddle boards that mate the 2 * Type C connectors to the logic board. Be sure they are solid in the mating and no bent pins. They are not expensive to source from Aliexpress.

                                      Any movement of connectors, cables, etc. should always be done with the power removed so to not short or surge the wrong components.

                                      A suggestion is to place your meter in DIODE mode. Remove all power to the logic board.

                                      Check and post the diode reading for EACH ACE controller as follows:

                                      red meter lead (yes, RED lead) to GROUND.
                                      black meter lead to the D+ pin of USB Type C connector (pick any one to start)


                                      Reading ?


                                      red meter lead (yes, RED lead) to GROUND.
                                      black meter lead to the D- pin of USB Type C connector (pick any one to start)


                                      Reading ?

                                      Then repeat for the NEXT USB connector till all 4 ports are inspected.

                                      Looking for possible damaged USB D+ / D- pin which likely means a damaged ACE controller which will halt the 20V dial up selection.

                                      See here for more details:

                                      https://logi.wiki/index.php?title=CD...le_view_mobile

                                      PS: See some typos in the schematic where the ACE controller is referenced as CD3215 on one sheet and CD3217 on another sheet. The logiwiki chats about both but the idea is the same. If one fails, the power contracts will not negotiate upto 20V. For example, U3100 is the primary controller and works with U3200 as the secondary controller. Both work together else PD will fail.
                                      Attached Files

                                      Comment


                                        #20
                                        Re: macbook a2141 board 820-1700 no turn on

                                        yes ,i have 4 * Type C ports on the logic board

                                        On this note, i take it that you have tested other ports on this logic board to power the box.yes

                                        ok don t want to sound stupid but were is the USB D+ / D- pin on the schematic 0800-01700

                                        regards

                                        den

                                        Comment

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