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LG 42LF561V No Video after backlight repair

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    #21
    Re: LG 42LF561V No Video after backlight repair

    Take a torch and shine around the edge of the lcd panel and check for any hairline cracks.

    Do you have sound coming through ?

    Comment


      #22
      Re: LG 42LF561V No Video after backlight repair

      No Scope in fact would not know where to start if I had one

      Comment


        #23
        Re: LG 42LF561V No Video after backlight repair

        Can not see any screen damage and no sound

        Comment


          #24
          Re: LG 42LF561V No Video after backlight repair

          Are you sure you get 0V at the Vin test point? Vin test point should be connected to the output side of the fuse (right terminal of the Fuse).
          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


            #25
            Re: LG 42LF561V No Video after backlight repair

            budm a question, in fault finding no picture issues is it possible too test if lvds signal/voltage is going from the mainboard to the tcon if so can this be measured with a multi meter or will only a scope show the signal/voltage thanks.

            Comment


              #26
              Re: LG 42LF561V No Video after backlight repair

              Sorry budm missed that testpoint but I can see it on my picture, can not check now as away from home till monday (working), but will check it as soon as I am back home.
              Have got 13.3v at both ends of the fuse F1
              I did notice big chip U11 seemed to be very very very hot when powered on, barely touchable
              definately no voltages on any testpoints near the two ribbon connectors to panel
              I have ordered a replacement tcon board (used) which should also arrive for monday

              Comment


                #27
                Re: LG 42LF561V No Video after backlight repair

                The LVDS will be very high and in mV range so DMM is not going to show anything much.
                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: LG 42LF561V No Video after backlight repair

                  Originally posted by budm View Post
                  The LVDS will be very high and in mV range so DMM is not going to show anything much.
                  thanks budm will have a read

                  Comment


                    #29
                    Re: LG 42LF561V No Video after backlight repair

                    Originally posted by london-freddie View Post
                    Sorry budm missed that testpoint but I can see it on my picture, can not check now as away from home till monday (working), but will check it as soon as I am back home.
                    Have got 13.3v at both ends of the fuse F1
                    I did notice big chip U11 seemed to be very very very hot when powered on, barely touchable
                    definately no voltages on any testpoints near the two ribbon connectors to panel
                    I have ordered a replacement tcon board (used) which should also arrive for monday
                    That may be a good way to try.
                    When you install a new T-CON, check the Voltages at those test points to see if they are present or not.
                    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


                      #30
                      Re: LG 42LF561V No Video after backlight repair

                      Yes only a couple of pounds for the used tcon, so worth a try, will test voltages as soon as I fit it
                      Is it normal for that U11 chip to get so hot

                      Comment


                        #31
                        Re: LG 42LF561V No Video after backlight repair

                        Usually When a chip is to hot to touch its shorted .Ive read that shorted leds can take out a t-con . i thought that is what happened when i tried subing leds and they blew but not in my case. Possibly static discharge ect.
                        I would say try with the pannel disconected but think its irellavent.

                        Comment


                          #32
                          Re: LG 42LF561V No Video after backlight repair

                          OK Good news just got home from work and Mr Postman had delivered me a used tcon, just fitted it and picture has come back to life. So tcon had failed, maybe as bman4 stated the shorted leds had taken out the tcon, but tv did have a picture before I replaced the leds

                          Comment


                            #33
                            Re: LG 42LF561V No Video after backlight repair

                            I know it's a old thread but just wanted to share the same warning - if you have bad LED strips, take the connector out. The Heesung/AUO T-Cons are horribly sensible to bad LEDs.

                            As such, after replacing the T-Con, from a functioning TV sans backlight I have gone back to square one:

                            - new T-Con will NOT output any image regardless whether I take out one flex or another
                            - old T-Con also won't output image unless I take out the flex cable that goes to the left half of the screen

                            I suspect the old one might be salvageable, whereas the new one is as good as trash, likely. Would love some short insight from y'all before opening a thread. Same model btw, 42LF561V.
                            Last edited by Dan81; 06-17-2023, 08:07 PM.
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