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Dell 3421, No Power.....

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    Dell 3421, No Power.....

    Brother, i Have problem with dell 3421 no power issue. Its 5v, 3v ok. I have flashed bios. but no power. SIO power 3.3v and VCC POR 3.3v ok. But Sio not release Rsm_RST. So dont know whats wrong. can any body point out this problem.
    Attached Files
    Last edited by nazrul145; 11-01-2014, 07:11 AM.

    #2
    Re: Dell 3421, No Power.....

    your RSMRST from southbridge that goes to SIO chip so if its missing then do a reflow or change the chip.
    typical DELL come on
    Just cook it! It's already broken.

    Comment


      #3
      Re: Dell 3421, No Power.....

      Thanks, but i already reflow southbridge. is rsmrst# goes to sio to southbridge? or southbridge to sio chip.

      Comment


        #4
        Re: Dell 3421, No Power.....

        sio to southbridge
        Check SIO

        Comment


          #5
          Re: Dell 3421, No Power.....

          Originally posted by MDY View Post
          sio to southbridge
          Check SIO
          RSMRST does not come from southbridge and goes to SIO?
          Just cook it! It's already broken.

          Comment


            #6
            Re: Dell 3421, No Power.....

            Do you have all the conditions prior to RSMRST met?
            Attached Files

            Comment


              #7
              Re: Dell 3421, No Power.....

              Thanks everybody speacially Khaahk. I have noticed that 5v_s5 and 3.3v_s5 is not present in U3601 AND U3602. But I have a same working Motherboard this board also 5v_s5 n 3d3_s5 is not preset without power button press. But this schematic indicate 5v_s5 and 3.3v_s5 must be ok befor rsm_rst#. I dont know what happend.

              Comment


                #8
                Re: Dell 3421, No Power.....

                Both powered from adapter?

                Comment


                  #9
                  Re: Dell 3421, No Power.....

                  No, i used bench power supply. Both from power supply, also use adapter. The ok motherboard RSMRST# is ok but faulty motherboard rsmrst not present.

                  Comment


                    #10
                    Re: Dell 3421, No Power.....

                    It beeps 3x..

                    Comment


                      #11
                      Re: Dell 3421, No Power.....

                      do a reflow!
                      Just cook it! It's already broken.

                      Comment


                        #12
                        Re: Dell 3421, No Power.....

                        Originally posted by dj_ricoh View Post
                        do a reflow!
                        Hi bro I was googling around to get the schematic of this board, and I finally
                        could get it on this thread.
                        So what happens is I got this notebook, and as soon as I plug the dc adapter the PSU light goes off. So there's a short somewhere. some guys form chip level repair told me to go straight to the VCC core section and lift all fets and check them I did that, and fets were fine.
                        Then I focused myself on the VIN section I lifted all fets and they were fine.
                        any ideas how I should go on, I'm thinking on 3v 5v always regulator and fets.
                        But I'm starting to think maybe the SIO could be shorted.
                        can you give me some ideas. Thanks. I have a lab supply to inject voltage if needed.

                        Comment


                          #13
                          Re: Dell 3421, No Power.....

                          check power on rst,then scl and sda with cro if not change I/o
                          sigpic

                          Comment


                            #14
                            Re: Dell 3421, No Power.....

                            Originally posted by dssence View Post
                            Hi bro I was googling around to get the schematic of this board, and I finally
                            could get it on this thread.
                            So what happens is I got this notebook, and as soon as I plug the dc adapter the PSU light goes off. So there's a short somewhere. some guys form chip level repair told me to go straight to the VCC core section and lift all fets and check them I did that, and fets were fine.
                            Then I focused myself on the VIN section I lifted all fets and they were fine.
                            any ideas how I should go on, I'm thinking on 3v 5v always regulator and fets.
                            But I'm starting to think maybe the SIO could be shorted.
                            can you give me some ideas. Thanks. I have a lab supply to inject voltage if needed.
                            in that case you cut a dell cable jack. connect it to the Lab PSU and go slowly up until it heats up your bad component.
                            and go like that untill you find all the bad components and the PSU does not consume anymore!
                            Just cook it! It's already broken.

                            Comment


                              #15
                              Re: Dell 3421, No Power.....

                              turning this old thread live again to know the solution for 3 beeps error.
                              and also PL4401 is grounded.

                              Looks like PU4201 is dead, will replace it and let you know but what was the earlier fix.
                              Last edited by dspok; 09-05-2015, 10:57 PM.

                              Comment


                                #16
                                Re: Dell 3421, No Power.....

                                inject psu to short to see burning component

                                Comment


                                  #17
                                  Re: Dell 3421, No Power.....

                                  Originally posted by ktmmotocross View Post
                                  inject psu to short to see burning component
                                  PSU didn't help. Replaced PU4201 and it worked.

                                  Comment


                                    #18
                                    Re: Dell 3421, No Power.....

                                    Thanks for update schematic

                                    Comment


                                      #19
                                      Re: Dell 3421, No Power.....

                                      My personal experience is PM_PWRBTN# signal is lost and I just reflow the chipset and the laptop can switch on. Thank's for sharing the schematic

                                      Comment


                                        #20
                                        Re: Dell 3421, No Power.....

                                        Thx for file

                                        Comment

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