LG 42PC3D - Flashing picture, sound works

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  • padstack
    New Member
    • Mar 2015
    • 5
    • United States
    #1

    LG 42PC3D - Flashing picture, sound works

    First off - I'm not a pro at all, but I know how to use a multimeter and have basic electronic knowledge.

    All fuses on Zsus and Ysus test fine. IPM on Ysus is not shorted anywhere (except the grounds, obviously). Va and Vs both show voltages that are roughly double the label on the panel.

    The TV flickers 2-3 times/second. You can "see" what's on the screen but the colors are significantly off. With every flicker, you can hear a "click" from the area of the IPM on the Ysus board (i.e. about 2-3 per second).

    Any idea where to start? Really clean TV but I've read enough on here to know they aren't exactly bastion of reliability...

    I read a lot of threads mentioning no picture or faded picture and a couple with flashing pictures, but those all had blown fuses. This one has no blown fuses at all.

    Thank you!
    Tags: None
    • tw2005
      Badcaps Legend
      • Oct 2011
      • 6458
      • Australia
      #2
      Re: LG 42PC3D - Flashing picture, sound works

      not going to be able to help much but double voltage suggests you may have the meter set wrong. set to DC Volts ?

      post some pictures of the display and the boards. IPM maybe be failing, check the buffer boards out for shorts and some of these LG buffers have FETs on those that can short.

        Comment

        • Alastair E
          Chief Womble
          • Mar 2013
          • 1963
          • U.K.
          #3
          Re: LG 42PC3D - Flashing picture, sound works

          A pretty common fault. One of the IPM's is failing/failed. These old LG sets are getting fairly old and have an average of 15-20,000 hours on 'em from the ones Ive repaired with same issues

          In my experience its the IPM on the Z-SUS that fails in this way more often than not....

          --Worth checking the Voltage across one of the row of red film caps on both the Y-SUS and Z-SUS. These are the ERC caps, and generally its the ERC side of the IPM that fails....

          As to Reliability, 15,000 hours of trouble-free service is Infinitely better than an average of 4-5K--Like the 2010/11 Panasonics!

          When you get the set running--You can check the hours on it by holding both Remote menu and Set menu buttons for more than 5 seconds.....

          BTW--IF the Va and Vs were double what was correct--The set would self-destruct --rather spectacularly I should imagine....
          --Either your meter is faulty, set to wrong range or being affected by the EM radiation from the Y-SUS.....

          The fault is unlikely the Buffers or the MOSFETS on the buffer-boards--MOSFETS failing short on these cause a vertical white bar that moves about the screen.....
          Short buffer-chip causes no image or panel priming, due to no/low VSC and -Vy
          Last edited by Alastair E; 03-27-2015, 10:43 AM.
          TELEFIX

          How PLASMA SCREENS WORK, X-SUS and Y-SUS what they do--
          http://www.irf.com/technical-info/appnotes/an-1088.pdf
          PLEASE DO NOT EMAIL ME PRIVATELY FOR REPAIR ADVICE. QUESTIONS BELONG ON THE FORUM!

            Comment

            • padstack
              New Member
              • Mar 2015
              • 5
              • United States
              #4
              Re: LG 42PC3D - Flashing picture, sound works

              Originally posted by Alastair E
              A pretty common fault. One of the IPM's is failing/failed. These old LG sets are getting fairly old and have an average of 15-20,000 hours on 'em from the ones Ive repaired with same issues

              In my experience its the IPM on the Z-SUS that fails in this way more often than not....

              --Worth checking the Voltage across one of the row of red film caps on both the Y-SUS and Z-SUS. These are the ERC caps, and generally its the ERC side of the IPM that fails....

              As to Reliability, 15,000 hours of trouble-free service is Infinitely better than an average of 4-5K--Like the 2010/11 Panasonics!

              When you get the set running--You can check the hours on it by holding both Remote menu and Set menu buttons for more than 5 seconds.....

              BTW--IF the Va and Vs were double what was correct--The set would self-destruct --rather spectacularly I should imagine...
              --Either your meter is faulty, set to wrong range or being affected by the EM radiation from the Y-SUS.....

              The fault is unlikely the Buffers or the MOSFETS on the buffer-boards--MOSFETS failing short on these cause a vertical white bar that moves about the screen.....
              Short buffer-chip causes no image or panel priming, due to no/low VSC and -Vy
              Lol! I'll double check the voltages! Thanks for the heads up! Looks like it's going nuclear soon!

              I'll check the voltage on the caps. Hopefully I don't botch that too!

              I appreciate the feedback. Is the clicking IPM on the ysus a problem or is it just a function of the Zsus failure and will most likely go away if/when the zsus IPM is replaced?

              Lastly, do you happen to have a part number for the zsus IPM?

              Thank you again!!
              Last edited by padstack; 03-27-2015, 10:42 PM.

                Comment

                • mmartell
                  Badcaps Legend
                  • Oct 2013
                  • 3189
                  • Canada
                  #5
                  Re: LG 42PC3D - Flashing picture, sound works

                  A clicking ipm needs to be replaced as it is failing or more simply, failed. Some fail short and blow the fuse, others fail intermittently open - hence the clicking - until finally they will stay open.

                    Comment

                    • Alastair E
                      Chief Womble
                      • Mar 2013
                      • 1963
                      • U.K.
                      #6
                      Re: LG 42PC3D - Flashing picture, sound works

                      Yppd-j018c
                      TELEFIX

                      How PLASMA SCREENS WORK, X-SUS and Y-SUS what they do--
                      http://www.irf.com/technical-info/appnotes/an-1088.pdf
                      PLEASE DO NOT EMAIL ME PRIVATELY FOR REPAIR ADVICE. QUESTIONS BELONG ON THE FORUM!

                        Comment

                        • padstack
                          New Member
                          • Mar 2015
                          • 5
                          • United States
                          #7
                          Re: LG 42PC3D - Flashing picture, sound works

                          Thank you both! What's the part number for the ysus IPM?
                          Last edited by padstack; 03-29-2015, 09:44 PM.

                            Comment

                            • Alastair E
                              Chief Womble
                              • Mar 2013
                              • 1963
                              • U.K.
                              #8
                              Re: LG 42PC3D - Flashing picture, sound works

                              Both Y and Z are YPPD-J018C
                              TELEFIX

                              How PLASMA SCREENS WORK, X-SUS and Y-SUS what they do--
                              http://www.irf.com/technical-info/appnotes/an-1088.pdf
                              PLEASE DO NOT EMAIL ME PRIVATELY FOR REPAIR ADVICE. QUESTIONS BELONG ON THE FORUM!

                                Comment

                                • padstack
                                  New Member
                                  • Mar 2015
                                  • 5
                                  • United States
                                  #9
                                  Re: LG 42PC3D - Flashing picture, sound works

                                  Thank you! Sorry for not catching that on my own. I appreciate it!

                                    Comment

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