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LENOVO NM-A841 Missing 5v/3v voltages

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    LENOVO NM-A841 Missing 5v/3v voltages

    Hi board CG521 NM-A841 REV 1.0
    NO POWER

    PU301
    PIN1 - 19V
    PIN2 - 19V
    PIN3 - 19V
    PIN4 - 19V
    PIN5 - 19V
    PIN6 - 5.8V
    PIN7 - 0V
    PIN8 -0V
    PIN9 -0V
    PIN10 -0
    PIN11 -0V
    PIN12 -19V
    PIN13- 19V
    PIN14 -19V
    PIN15 - 5.8
    PIN16 - 0V

    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

    Hi i hope someone can help me with this issue

    checling coil impendace PL501,PL401,PL402 is ok no shorted
    Attached Files

    #2
    Re: LENOVO Missing 5v/3v voltages

    Is this with battery removed? Check if PQ309 and/or PQ303 is shorted (D/S/G). 19V on Battery Charging Rail is too much in my opinion.
    FairRepair on YouTube

    Comment


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

      Originally posted by Sephir0th View Post
      Is this with battery removed? Check if PQ309 and/or PQ303 is shorted (D/S/G). 19V on Battery Charging Rail is too much in my opinion.
      yes without the battery sir

      pq309 and pq303 is not shorted sir
      Last edited by kalilinux25; 01-07-2021, 01:36 AM.

      Comment


        #4
        Re: LENOVO Missing 5v/3v voltages

        Check again pin11 PU401 cannot be +19V it should be approximately 3V-3.3V
        Last edited by SMDFlea; 12-30-2021, 05:11 PM.

        Comment


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

          Originally posted by techtiger View Post
          Check again pin11 cannot be +19V it should be approximately 3V-3.3V
          sorry pin 11 has 0v sir

          Comment


            #6
            Re: LENOVO Missing 5v/3v voltages

            Pin 17 is vcc internal ldo output should be 3.3v here

            Pin 11 is enable2 can be 19v as connected to input supply, needed to turn on ic


            Pin12 is enable1 pin coming from KBC ec-on


            Pin---17=0 no ldo supply check again

            Pin---12=0 volt no en to generate pwm operation coil supply

            Pin11=supply to turn on ic

            Comment


              #7
              Re: LENOVO Missing 5v/3v voltages

              Test all requirements of SIO & pin 85 ? Yep correct EN2 is +19V EN1 can go up to +4.5V I have to get a new pair of glasses
              Last edited by Techtiger; 01-07-2021, 04:52 AM.

              Comment


                #8
                Re: LENOVO Missing 5v/3v voltages

                Originally posted by stingerchamp View Post
                Pin 17 is vcc internal ldo output should be 3.3v here

                Pin 11 is enable2 can be 19v as connected to input supply, needed to turn on ic


                Pin12 is enable1 pin coming from KBC ec-on


                Pin---17=0 no ldo supply check again

                Pin---12=0 volt no en to generate pwm operation coil supply

                Pin11=supply to turn on ic
                pin 17 has 0v
                pin 12 0v
                pin 11 0v

                so the ic is dead? or other aprts?

                Comment


                  #9
                  Re: LENOVO Missing 5v/3v voltages

                  Input voltage supply is missing, first check pin---11 voltage and how is it possible that you have 19v at pin 5 and not at pin11

                  Can not tell now
                  Last edited by stingerchamp; 01-07-2021, 09:18 PM.

                  Comment


                    #10
                    Re: LENOVO Missing 5v/3v voltages

                    Originally posted by stingerchamp View Post
                    Input voltage supply is missing, first check pin---11 voltage and how is it possible that you have 19v at pin 5 and not at pin11

                    Can not tell now
                    can i try to pump voltage in pin 11 sir?

                    Comment


                      #11
                      Re: LENOVO Missing 5v/3v voltages

                      No

                      Check pin 5 voltage 19v stable or dropping

                      Comment


                        #12
                        Re: LENOVO Missing 5v/3v voltages

                        Originally posted by stingerchamp View Post
                        No

                        Check pin 5 voltage 19v stable or dropping
                        very stable sir nothing is going drop

                        Comment


                          #13
                          Re: LENOVO Missing 5v/3v voltages

                          Look at the trace on pu401 pin 11 ,are there any resistors connected to it. Don't inject any voltage on pin 11 ! .The LA-C371P schematic has pin 11 as ENLDO_3V5V ,it goes through a voltage divider.

                          https://drive.google.com/file/d/1NK6...OCOaFraFV/view
                          Last edited by SMDFlea; 01-07-2021, 10:57 PM.
                          All donations to badcaps are welcome, click on this link to donate. Thanks to all supporters

                          Comment


                            #14
                            Re: LENOVO Missing 5v/3v voltages

                            Pin11 has no resistor as per schematic but check again
                            Last edited by stingerchamp; 01-07-2021, 11:07 PM.

                            Comment


                              #15
                              Re: LENOVO Missing 5v/3v voltages

                              Originally posted by SMDFlea View Post
                              Look at the trace on pu401 pin 11 ,are there any resistors connected to it. Don't inject any voltage on pin 11 ! .The LA-C371P schematic has pin 11 as ENLDO_3V5V ,it goes through a voltage divider.

                              https://drive.google.com/file/d/1NK6...OCOaFraFV/view
                              nope sir I dint inject it .

                              Comment


                                #16
                                Re: LENOVO Missing 5v/3v voltages

                                Originally posted by stingerchamp View Post
                                Pin11 has no resistor as per schematic but check
                                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

                                .
                                Last edited by SMDFlea; 01-07-2021, 11:15 PM.
                                All donations to badcaps are welcome, click on this link to donate. Thanks to all supporters

                                Comment


                                  #17
                                  Re: LENOVO Missing 5v/3v voltages

                                  I agree, physically check any resistor attached to this pin---11

                                  At least ldo should come out at pin---17 but since ic is not getting vcc no chance

                                  Comment


                                    #18
                                    Re: LENOVO Missing 5v/3v voltages

                                    Originally posted by stingerchamp View Post
                                    I agree, physically check any resistor attached to this pin---11

                                    At least ldo should come out at pin---17 but since ic is not getting vcc no chance
                                    whats the verdict sir?

                                    Comment


                                      #19
                                      Re: LENOVO Missing 5v/3v voltages

                                      Trace pin 11 to any resistor attached or not in beep mode

                                      Comment


                                        #20
                                        Re: LENOVO Missing 5v/3v voltages

                                        Originally posted by kalilinux25 View Post
                                        whats the verdict sir?
                                        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
                                        Last edited by SMDFlea; 01-07-2021, 11:42 PM.
                                        All donations to badcaps are welcome, click on this link to donate. Thanks to all supporters

                                        Comment

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