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Lenovo 100-15idb NM-A681 no turning on

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    Lenovo 100-15idb NM-A681 no turning on

    Hello, laptop is not turning on. Motherboard Mark: NM-A681 rev 1.0 UMA
    Here are the measurements I've taken:
    PR301:
    2.2mohm and goes down

    PQ301:
    S: 19.59V
    G: 19.575V
    D: 20.1V

    PQ302:
    S: 19,594V
    G: 19.576V
    D: 0,0022V
    Diode test: 0,5341V
    I don't have short circuit between S and G.
    What should I measure next? Please help
    Greetings 😁

    #2
    Re: Lenovo 100-15idb NM-A681 no turning on

    Originally posted by lapfix View Post
    lenovo ideapad 100 CG410/CG510 NM-A681 Schematic and BVD
    https://www.badcaps.net/forum/showth...37#post1044937

    .
    Last edited by Vesko356; 04-19-2023, 04:44 AM.
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    Comment


      #3
      Re: Lenovo 100-15idb NM-A681 no turning on

      Remove all power -> meter in resistance mode.

      Measure the resistance between the following pins on each of the above mosfets:

      source (1-2-3) & drain (5-6-7-8)
      source (1-2-3) & gate (4)
      gate (4) & drain (5-6-7-8)


      Post each measurement.

      Comment


        #4
        Re: Lenovo 100-15idb NM-A681 no turning on

        Thanks for reply. I checked signal ACOFF and there is 0v. I measured on 98 pin od kbc, so do I need to replace KBC? I still learn.

        Comment


          #5
          Re: Lenovo 100-15idb NM-A681 no turning on

          Can you link or post the schematic? The above mosfets, are not enabled. If they are N-channel type, then gate voltage must be boosted to ~25v to enable. If P-channel, gate must be lower than the source / drain voltage.

          The charger IC will decide when to enable or not.

          Post the schematic link. Then post the resistance checks after removing all power. Checking if the mosfets are defective.

          Comment


            #6
            Re: Lenovo 100-15idb NM-A681 no turning on

            PQ301:
            Source - drain: 0.623mohm
            Source - Gate: 0.1955mohm
            Gate - drain: 0.44mohm

            PQ302:
            Source - drain: 0.27mohm and goes to 1mohm
            Source - Gate: 0.195mohm
            Gate - drain: 0.43mohm and increase to ~1mohm

            I use schematic and boardview from this post:
            https://www.badcaps.net/forum/showth...37#post1044937

            Comment


              #7
              Re: Lenovo 100-15idb NM-A681 no turning on

              Check the voltage to ground of PACIN.

              Comment


                #8
                Re: Lenovo 100-15idb NM-A681 no turning on

                Voltage to ground PACIN: 3.26V

                Comment


                  #9
                  Re: Lenovo 100-15idb NM-A681 no turning on

                  Locate PQ307B. Check the voltage to ground of pins 3, 4 and also 5. Post the readings.

                  Comment


                    #10
                    Re: Lenovo 100-15idb NM-A681 no turning on

                    Pq307b:
                    3-0.0234v
                    4-gnd
                    5-0.0086v

                    Comment


                      #11
                      Re: Lenovo 100-15idb NM-A681 no turning on

                      Check the voltage to ground of pq998.

                      Next, remove all power. Meter in resistance mode. Check the resistance across pr309.

                      Comment


                        #12
                        Re: Lenovo 100-15idb NM-A681 no turning on

                        Voltage to ground PQ998:
                        1-0.0086V
                        2-0.035V
                        3-GND

                        PR309- 31.82kohm

                        Comment


                          #13
                          Re: Lenovo 100-15idb NM-A681 no turning on

                          Check the voltage to ground of pr309. Check both sides.

                          Comment


                            #14
                            Re: Lenovo 100-15idb NM-A681 no turning on

                            PR309
                            Pin 1 (PACIN) - 3.263V
                            Pin 2 (PACIN_G) - 0.0086V

                            Comment


                              #15
                              Re: Lenovo 100-15idb NM-A681 no turning on

                              Remove all power. Check the resistance to ground of pin #2 of pr309.

                              Comment


                                #16
                                Re: Lenovo 100-15idb NM-A681 no turning on

                                Pin #2 of PR309: 128.30ohm

                                Comment


                                  #17
                                  Re: Lenovo 100-15idb NM-A681 no turning on

                                  Flux and remove pq998. Then check the voltage again on each side of pr309.

                                  Comment


                                    #18
                                    Re: Lenovo 100-15idb NM-A681 no turning on

                                    After removing pq998:
                                    PR309:
                                    1-3.259V
                                    2-0.0086V

                                    Comment


                                      #19
                                      Re: Lenovo 100-15idb NM-A681 no turning on

                                      Something is wrong in this region. Flux and remove pq307. Then check the voltage again on each side of pr309. The resistance to ground on the gate pin should not be so low.

                                      Comment


                                        #20
                                        Re: Lenovo 100-15idb NM-A681 no turning on

                                        After removing PQ307
                                        1-3.32 voltage to ground, 100.67kohm (no power)
                                        2-3.309 voltage to ground, 147.77kohm (no power)
                                        So do i need to find and replace PQ307?

                                        Comment

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