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Dell 2005 FPW 2 and power flashing

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    #21
    Re: Dell 2005 FPW 2 and power flashing

    Originally posted by budm View Post
    6-pin device U612 si3865, is the on/off pin fluctuating so the output will be fluctuating too.
    So need to find out why the control pin is going up and down.
    Do you have the link for the diagram or you can just upload it.
    Here is the service manual with schematics.
    Attached Files
    Last edited by Nightwolf; 03-15-2015, 08:58 PM.

    Comment

      #22
      Re: Dell 2005 FPW 2 and power flashing

      I'm not sure but I don't think that is a regulator, unless they are using it as one somehow.
      That device to the right of it in the photo with 1117 on it, that will be a regulator.
      Attached Files
      "Tantalum for the brave, Solid Aluminium for the wise, Wet Electrolytic for the adventurous"
      -David VanHorn

      Comment

        #23
        Re: Dell 2005 FPW 2 and power flashing

        It is electronic switch FOR 3.3V for 3.3c DVI.
        I wonder if other ON/OFF signals for U602, 603, 611 as shown in the manual are also fluctuating.
        Last edited by budm; 03-15-2015, 09:00 PM.
        Never stop learning
        Basic LCD TV and Monitor troubleshooting guides.
        http://www.badcaps.net/forum/showthr...956#post305956

        Voltage Regulator (LDO) testing:
        http://www.badcaps.net/forum/showthr...999#post300999

        Inverter testing using old CFL:
        http://www.badcaps.net/forum/showthr...er+testing+cfl

        Tear down pictures : Hit the ">" Show Albums and stories" on the left side
        http://s807.photobucket.com/user/budm/library/

        TV Factory reset codes listing:
        http://www.badcaps.net/forum/showthread.php?t=24809

        Comment

          #24
          Re: Dell 2005 FPW 2 and power flashing

          Yes it is.

          Comment

            #25
            Re: Dell 2005 FPW 2 and power flashing

            Originally posted by Agent24 View Post
            I'm not sure but I don't think that is a regulator, unless they are using it as one somehow.
            That device to the right of it in the photo with 1117 on it, that will be a regulator.
            U606, U608 and U610 are the regulators and they all put out 3.3v.
            The 3.3_SW comes from the display processor.

            Comment

              #26
              Re: Dell 2005 FPW 2 and power flashing

              I wonder if U402 is in some reset loop?

              Check PWR_RSTN from R451 (should be near U405)?
              "Tantalum for the brave, Solid Aluminium for the wise, Wet Electrolytic for the adventurous"
              -David VanHorn

              Comment

                #27
                Re: Dell 2005 FPW 2 and power flashing

                So some how the processor outputs are cycling on and off for other switches as well then.
                Never stop learning
                Basic LCD TV and Monitor troubleshooting guides.
                http://www.badcaps.net/forum/showthr...956#post305956

                Voltage Regulator (LDO) testing:
                http://www.badcaps.net/forum/showthr...999#post300999

                Inverter testing using old CFL:
                http://www.badcaps.net/forum/showthr...er+testing+cfl

                Tear down pictures : Hit the ">" Show Albums and stories" on the left side
                http://s807.photobucket.com/user/budm/library/

                TV Factory reset codes listing:
                http://www.badcaps.net/forum/showthread.php?t=24809

                Comment

                  #28
                  Re: Dell 2005 FPW 2 and power flashing

                  Originally posted by budm View Post
                  So some how the processor outputs are cycling on and off for other switches as well then.
                  Oops. Yeah that doesn't make sense, does it? Then at least U603 would also get switched and U610 would not produce steady output... Never mind then.
                  "Tantalum for the brave, Solid Aluminium for the wise, Wet Electrolytic for the adventurous"
                  -David VanHorn

                  Comment

                    #29
                    Re: Dell 2005 FPW 2 and power flashing

                    Originally posted by Agent24 View Post
                    I wonder if U402 is in some reset loop?

                    Check PWR_RSTN from R451 (should be near U405)?
                    R451 is 2.19 to 4 9v

                    Comment

                      #30
                      Re: Dell 2005 FPW 2 and power flashing

                      Wait, so the voltage on R451 IS fluctuating?

                      What do you get on Pins 1 and 3 of U405?
                      "Tantalum for the brave, Solid Aluminium for the wise, Wet Electrolytic for the adventurous"
                      -David VanHorn

                      Comment

                        #31
                        Re: Dell 2005 FPW 2 and power flashing

                        Originally posted by Agent24 View Post
                        Wait, so the voltage on R451 IS fluctuating?

                        What do you get on Pins 1 and 3 of U405?
                        pin 1 is 5v, pin 3 is fluctuating. Q401 base .65v, C.028v
                        Q403 C .002 - .005v

                        Comment

                          #32
                          Re: Dell 2005 FPW 2 and power flashing

                          Not sure R450 is in the circuit.

                          Comment

                            #33
                            Re: Dell 2005 FPW 2 and power flashing

                            Possibly, it has a star next to it in schematic which could indicate it is unused. Sometimes they design things in and then don't use them in production, or it's for a different model.

                            Can you remove R451 and see if the output voltage of U405 becomes stable?
                            "Tantalum for the brave, Solid Aluminium for the wise, Wet Electrolytic for the adventurous"
                            -David VanHorn

                            Comment

                              #34
                              Re: Dell 2005 FPW 2 and power flashing

                              Originally posted by Agent24 View Post
                              Possibly, it has a star next to it in schematic which could indicate it is unused. Sometimes they design things in and then don't use them in production, or it's for a different model.

                              Can you remove R451 and see if the output voltage of U405 becomes stable?
                              That's going to be a tough one. Think my iron is way too hot for that SMT resistor. My have to take the board to work and use the hot tweezers on it. It looks like a 0 ohm part too.

                              Comment

                                #35
                                Re: Dell 2005 FPW 2 and power flashing

                                You could try disconnect Pin 3 of U405 instead? It might be easier, they say it's a TO-92 package in the manual.
                                "Tantalum for the brave, Solid Aluminium for the wise, Wet Electrolytic for the adventurous"
                                -David VanHorn

                                Comment

                                  #36
                                  Re: Dell 2005 FPW 2 and power flashing

                                  Sorry haven't had time to do either of these thing yet, working crazy hours. Should be able to do in the morning and let you know what I find. Thanks for all the help so far.

                                  Comment

                                    #37
                                    Re: Dell 2005 FPW 2 and power flashing

                                    OK. With R451 removed, one side reads 4.98v and the other side reads ov. Also with it removed, all four 4 lights (1 2 3 4) and the power light is on solid.1 and 2 are yellow, 3 and 4 are green and the power light is yellow. When I read the 0v side, all lights go out. When I remove the meter lead, the 4 numbers come back on the same way but the power light does not come on until I unplug it and plug it back in.
                                    Last edited by Nightwolf; 03-17-2015, 09:42 PM.

                                    Comment

                                      #38
                                      Re: Dell 2005 FPW 2 and power flashing

                                      Seems like either U405 can't handle a load for some reason, or perhaps the reset pin on U402 is bad. Unless budm has any other ideas, it's all I can think of.

                                      What resistance do you get from the 0v side of R451 to GND?
                                      "Tantalum for the brave, Solid Aluminium for the wise, Wet Electrolytic for the adventurous"
                                      -David VanHorn

                                      Comment

                                        #39
                                        Re: Dell 2005 FPW 2 and power flashing

                                        I get an open to ground. Also where does that signal (PWR_RSTN) go? I tried looking for it but haven't found it.

                                        Comment

                                          #40
                                          Re: Dell 2005 FPW 2 and power flashing

                                          It goes to the /RESET pin of the U402 IC.
                                          "Tantalum for the brave, Solid Aluminium for the wise, Wet Electrolytic for the adventurous"
                                          -David VanHorn

                                          Comment

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