Faulty 42LG3000 Help!

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  • danjcarr1
    Member
    • Jul 2012
    • 35
    • Uk

    #1

    Faulty 42LG3000 Help!

    Hi all,

    I have a faulty 42LG3000 TV.

    The fault is that when the set is powered on it comes on and the image flashes on the screen for a second if that, then the display goes black although the sound can still be heard.

    Has anyone ever encounted this fault?

    Any advice would be greatly appreciated.

    Dan
  • tom66
    EVs Rule
    • Apr 2011
    • 32560
    • UK

    #2
    Re: Faulty 42LG3000 Help!

    It sounds like 2 seconds to black; quite a common issue in fact. I just fixed a TV with this fault. A good start would be to post pictures of the insides of your TV.
    Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
    For service manual, schematic, boardview (board view), datasheet, cad - use our search.

    Comment

    • danjcarr1
      Member
      • Jul 2012
      • 35
      • Uk

      #3
      Re: Faulty 42LG3000 Help!

      Ok thanks Tom, I will dig out the camera and post some pictures

      Comment

      • danjcarr1
        Member
        • Jul 2012
        • 35
        • Uk

        #4
        Re: Faulty 42LG3000 Help!

        Please find an attached image of my set minua psu

        Comment

        • tom66
          EVs Rule
          • Apr 2011
          • 32560
          • UK

          #5
          Re: Faulty 42LG3000 Help!

          On each side of the screen there is an inverter.

          Can you please take a closer picture of each inverter. Thanks.
          Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
          For service manual, schematic, boardview (board view), datasheet, cad - use our search.

          Comment

          • danjcarr1
            Member
            • Jul 2012
            • 35
            • Uk

            #6
            Re: Faulty 42LG3000 Help!

            I have repaired tvs in the past and there is nothing obvious to the eye that i can see.
            Also my fault sounds as if it may well be the two seconds to black that you mentioned. You can see the full screen image once first turned off then it goes black and only the sound can be heard.
            Dan

            Comment

            • danjcarr1
              Member
              • Jul 2012
              • 35
              • Uk

              #7
              Re: Faulty 42LG3000 Help!

              Master - VIT71053.54 LOGAH REV:0



              Slave - VIT71053.55 LOGAH REV:0



              Thanks Dan

              Comment

              • danjcarr1
                Member
                • Jul 2012
                • 35
                • Uk

                #8
                Re: Faulty 42LG3000 Help!



                Comment

                • tom66
                  EVs Rule
                  • Apr 2011
                  • 32560
                  • UK

                  #9
                  Re: Faulty 42LG3000 Help!

                  Okay on these sets the two inverters work with each other.

                  If the master is dead you will usually get nothing at all on the screen.

                  If the slave is dead you will sometimes get a brief flash or 2 seconds to black.

                  Each of the boards has a fuse on it; the white chunky object next to the power connector. Check this fuse with your meter.
                  Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
                  For service manual, schematic, boardview (board view), datasheet, cad - use our search.

                  Comment

                  • danjcarr1
                    Member
                    • Jul 2012
                    • 35
                    • Uk

                    #10
                    Re: Faulty 42LG3000 Help!

                    The fuse is fine. Dan

                    Comment

                    • tom66
                      EVs Rule
                      • Apr 2011
                      • 32560
                      • UK

                      #11
                      Re: Faulty 42LG3000 Help!

                      Originally posted by danjcarr1
                      The fuse is fine. Dan
                      On both? Okay, it looks as if all the controller stuff happens on the master. The slave is a "dumb" board.

                      There are some transformers on the boards; check the resistance between the markings (attached) on both boards.

                      If the transformers are good, the resistances will match within 3%.
                      Attached Files
                      Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
                      For service manual, schematic, boardview (board view), datasheet, cad - use our search.

                      Comment

                      • danjcarr1
                        Member
                        • Jul 2012
                        • 35
                        • Uk

                        #12
                        Re: Faulty 42LG3000 Help!

                        Yes fuses are fine on both. What setting do I need the meter on to check the reistance? Also do i need to put one end on the first red marking and the other end on the other red marking?
                        Then the same for the green markings?

                        Dan

                        Comment

                        • danjcarr1
                          Member
                          • Jul 2012
                          • 35
                          • Uk

                          #13
                          Re: Faulty 42LG3000 Help!

                          I have set the multi meter to 20k ohm and unless i am doing something wrong i am not getting any readings from any of them?

                          Comment

                          • tom66
                            EVs Rule
                            • Apr 2011
                            • 32560
                            • UK

                            #14
                            Re: Faulty 42LG3000 Help!

                            Originally posted by danjcarr1
                            I have set the multi meter to 20k ohm and unless i am doing something wrong i am not getting any readings from any of them?
                            One probe on one red, one probe on another red. Repeat for green. If you are still not getting a reading they might be wired differently to how I expect.
                            Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
                            For service manual, schematic, boardview (board view), datasheet, cad - use our search.

                            Comment

                            • danjcarr1
                              Member
                              • Jul 2012
                              • 35
                              • Uk

                              #15
                              Re: Faulty 42LG3000 Help!

                              Yeah that is what I tried. Not getting any readings.
                              Also tried on both inverters.

                              Dan

                              Comment

                              • tom66
                                EVs Rule
                                • Apr 2011
                                • 32560
                                • UK

                                #16
                                Re: Faulty 42LG3000 Help!

                                Can you post a side-on picture of the transformers?
                                Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
                                For service manual, schematic, boardview (board view), datasheet, cad - use our search.

                                Comment

                                • danjcarr1
                                  Member
                                  • Jul 2012
                                  • 35
                                  • Uk

                                  #17
                                  Re: Faulty 42LG3000 Help!

                                  Yes, will do it tomorrow as the tv is at my parents home. Thanks Dan

                                  Comment

                                  • danjcarr1
                                    Member
                                    • Jul 2012
                                    • 35
                                    • Uk

                                    #18
                                    Re: Faulty 42LG3000 Help!



                                    Comment

                                    • tom66
                                      EVs Rule
                                      • Apr 2011
                                      • 32560
                                      • UK

                                      #19
                                      Re: Faulty 42LG3000 Help!

                                      Okay so as far as I can see they are wired as I would expect. What range were you using your meter on?
                                      Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
                                      For service manual, schematic, boardview (board view), datasheet, cad - use our search.

                                      Comment

                                      • danjcarr1
                                        Member
                                        • Jul 2012
                                        • 35
                                        • Uk

                                        #20
                                        Re: Faulty 42LG3000 Help!

                                        I tired it on 2k and 20k. I have tried taking a reading from an inverter that i know works from another tv and i am getting a reading from that. Just not from either of the two inverter boards for this tv. Dan

                                        Comment

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