Mode#47LG70 screen blanking LG LCD 47"

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  • cheapshot
    Member
    • Jul 2012
    • 41
    • Bahamas
    #1

    Mode#47LG70 screen blanking LG LCD 47"

    Good day all. The referenced TV will cut on fine but as soon as a video source is plugged to ANY HDMI port, the screen's backlight will cut out and then back on and will do this about 10 times then stop for a few seconds then start again. This is not a flashing or strobe effect like I have seen a lot on here addressed. Its like the backlight literally cuts out then back in every half second.

    With no video input the TV stays on fine. Where should I start with this one?
    Tags: None
    • budm
      Badcaps Legend
      • Feb 2010
      • 40746
      • USA
      #2
      Re: Mode#47LG70 screen blanking LG LCD 47"

      Does it do that using other Video ports?
      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

        • cheapshot
          Member
          • Jul 2012
          • 41
          • Bahamas
          #3
          Re: Mode#47LG70 screen blanking LG LCD 47"

          Have not tried others but I can if needed? Wouldn't this point to power supply board if the inverters are powered from this board?

            Comment

            • budm
              Badcaps Legend
              • Feb 2010
              • 40746
              • USA
              #4
              Re: Mode#47LG70 screen blanking LG LCD 47"

              Originally posted by cheapshot
              Have not tried others but I can if needed? Wouldn't this point to power supply board if the inverters are powered from this board?
              Power supply is unstable, or inverter board is unstable, or the BL-ON or DIMMING signal form the main board are not steady.
              You have to take Voltage measurement at the least.
              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

                • cheapshot
                  Member
                  • Jul 2012
                  • 41
                  • Bahamas
                  #5
                  Re: Mode#47LG70 screen blanking LG LCD 47"

                  ok where should I test first? I can post back with what I see a bit later

                    Comment

                    • budm
                      Badcaps Legend
                      • Feb 2010
                      • 40746
                      • USA
                      #6
                      Re: Mode#47LG70 screen blanking LG LCD 47"

                      Why don't you try other Video ports first?
                      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

                        • Davi.p
                          Hobbist Tech
                          • Sep 2009
                          • 4318
                          • Italy - Milan
                          #7
                          Re: Mode#47LG70 screen blanking LG LCD 47"

                          Hi, do you have made tests always with the same video source? Same hdmi cable? Tried with source inserted with the tv sw.on from cold?
                          Last edited by Davi.p; 09-21-2016, 03:08 PM.

                            Comment

                            • cheapshot
                              Member
                              • Jul 2012
                              • 41
                              • Bahamas
                              #8
                              Re: Mode#47LG70 screen blanking LG LCD 47"

                              ok will try other sources but from cold screen will blink if source is inserted

                                Comment

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