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LENOVO NM-A841 Missing 5v/3v voltages

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    #21
    Re: LENOVO Missing 5v/3v voltages

    Originally posted by SMDFlea View Post
    Have you found any resistors connected to the pin 11 trace or does it go into a via through the board ? A board view would help but I'm not sure if it's available. Take a picture of pu401 with the surrounding parts
    gos via the board sir

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      #22
      Re: LENOVO Missing 5v/3v voltages

      Originally posted by SMDFlea View Post
      According to the nm-a841 schematic no ,but schematics aren't always right even though you expect them to be. It can't be 19v on pin 11. Let's gets other members views and fix this together

      .
      If you look at datasheet abs max Volt of en is 25v
      I read it wrong?

      Comment


        #23
        Re: LENOVO Missing 5v/3v voltages

        Originally posted by SMDFlea View Post
        Have you found any resistors connected to the pin 11 trace or does it go into a via through the board ? A board view would help but I'm not sure if it's available. Take a picture of pu401 with the surrounding parts

        Comment


          #24
          Re: LENOVO Missing 5v/3v voltages

          Originally posted by stingerchamp View Post
          If you look at datasheet abs max Volt of en is 25v
          I read it wrong?
          There is no datasheet for the SY8286BRAC .
          All donations to badcaps are welcome, click on this link to donate. Thanks to all supporters

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            #25
            Re: LENOVO Missing 5v/3v voltages

            Originally posted by kalilinux25 View Post
            gos via the board sir
            I read a post on a russian forum that pin 11 is indeed 19V .Just to be sure though inject voltage voltage on theat but but keep it low and slowly crank the voltage up.If you can get up to 19V then run a jumper between 2,3,4, or 5 to 11
            All donations to badcaps are welcome, click on this link to donate. Thanks to all supporters

            Comment


              #26
              Re: LENOVO Missing 5v/3v voltages

              Originally posted by SMDFlea View Post
              I read a post on a russian forum that pin 11 is indeed 19V .Just to be sure though inject voltage voltage on theat but but keep it low and slowly crank the voltage up.If you can get up to 19V then run a jumper between 2,3,4, or 5 to 11
              jumper on pin 11 checking voltage on all pins

              PU401
              PIN1- 0V
              PIN2,3,4,5 - 19V
              PIN6 0V
              PIN7 0V
              PIN8 0V
              PIN9 0V
              PIN 10 0V
              PIN 11 19V
              PIN12- 0V
              PIN13-0V
              PIN14-0V
              PIN15-1.3V
              PIN16 - 0V
              PIN17- 0V
              PIN18-0V
              PIN19-0V
              PIN20-0V

              PU301
              PIN1 - 19V
              PIN2 - 19V
              PIN3 - 19V
              PIN4 - 19V
              PIN5 - 19V
              PIN6 - 5.8V
              PIN7- 0V
              PIN8 -0V
              PIN9-0V
              PIN10-0V
              PIN11-0V
              PIN12-19V
              PIN13-19V
              PIN14 -19V
              PIN15- 5.8V
              PIN 16- 0V
              PIN13

              Comment


                #27
                Re: LENOVO Missing 5v/3v voltages

                Pu301 is ok

                Change pu401

                Check capacitor pc422

                Apply 3.3v with dc at pc422 and check with multimeter voltage drops or stable if stable change pu401
                Last edited by stingerchamp; 01-08-2021, 10:55 PM.

                Comment


                  #28
                  Re: LENOVO Missing 5v/3v voltages

                  Originally posted by stingerchamp View Post
                  Pu301 is ok

                  Change pu401

                  Check capacitor pc422

                  Apply 3.3v with dc at pc422 and check with multimeter voltage drops or stable if stable change pu401
                  I dont have a pu401 right now sir\ do i need to remove it beore adding voltage on pc422?

                  Comment


                    #29
                    Re: LENOVO Missing 5v/3v voltages

                    Yes remove it

                    Comment


                      #30
                      Re: LENOVO Missing 5v/3v voltages

                      Originally posted by stingerchamp View Post
                      Yes remove it
                      nothing is consuming at pc422 capacitor sir 3.3v no amp

                      Comment


                        #31
                        Re: LENOVO Missing 5v/3v voltages

                        Confirmed

                        Change pu401 and likely KBC as well

                        Comment


                          #32
                          Re: LENOVO Missing 5v/3v voltages

                          Originally posted by stingerchamp View Post
                          Confirmed

                          Change pu401 and likely KBC as well
                          its ha s same problem with my acer hehehe

                          Comment


                            #33
                            Re: LENOVO Missing 5v/3v voltages

                            Originally posted by stingerchamp View Post
                            Confirmed

                            Change pu401 and likely KBC as well
                            Good day sir I hope you can help me again I already cahnge the PU401 ic but I got the same reading on all pins

                            PU401

                            PIN1 - 0V
                            PIN2 - 19V
                            PIN3 - 19V
                            PIN4 - 19V
                            PIN5 - 19V
                            PIN6 - 0V
                            PIN7 - 0V
                            PIN8 -0V
                            PIN9 -0V
                            PIN10 -0V
                            PIN11 -19V
                            PIN12 -0V
                            PIN13- 0V
                            PIN14 -0V
                            PIN15 - 0V
                            PIN16 - 0V
                            PIN17 - 0V
                            PIN18 - 0V
                            PIN19 - 0V
                            PIN20 - 0V

                            ive tested the impedance of PL401 7KOHMS
                            PL402 27 Kohms is this normal sir?

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