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Insignia NS58DF620NA20 - have backlight but no picture

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    #1

    Insignia NS58DF620NA20 - have backlight but no picture

    Hi all! I have an Insignia NS58DF620NA20 TV here. When plugged in the power button illuminates blue. If I press the power button, the backlights turn on, but there is no picture. I can turn the TV on and off via the remote.
    How can I check whether the problem is the t-con or the main board? Is there a way to test the t-con board independently of the main board on this set (eg. bring up a color-cycling test pattern)?

    Thanks!
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    #2
    Re: Insignia NS58DF620NA20 - have backlight but no picture

    First is to check if you have 12v at your t-con. It's labeled near connector
    I assume no responsibility for any stupid suggestions I might post.

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      #3
      Re: Insignia NS58DF620NA20 - have backlight but no picture

      Tcon is first suspect with backlight but no video. Connect one side at a time between the tcon and panel to see if one side has an image.

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        #4
        Re: Insignia NS58DF620NA20 - have backlight but no picture

        Originally posted by dskall View Post
        First is to check if you have 12v at your t-con. It's labeled near connector
        Checked the test point. 12v present.

        Originally posted by neilc6 View Post
        Tcon is first suspect with backlight but no video. Connect one side at a time between the tcon and panel to see if one side has an image.
        Ok, I tried this. If I disconnect the right ribbon, I still get a black screen. If I disconnect the left ribbon, I get half white / half black screen (see pic).

        Another note: The TV will turn on and off with the remote. I tried pressing the different remote buttons (home, Netflix, etc) button to see if I could get anything on the screen in all 3 cases (both tcon ribbons connected, left disconnected, right disconnected) and resulted in no change. I either had fully black screen or the half white/half black as noted above.
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          #5
          Re: Insignia NS58DF620NA20 - have backlight but no picture

          Originally posted by dskall View Post
          ...
          Originally posted by neilc6 View Post
          ...
          What do you guys think? Next steps?

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            #6
            Re: Insignia NS58DF620NA20 - have backlight but no picture

            About the only way to test is to check for data coming out of main board. Or try heating up mainboard processor then plugging it in and see if it comes on. If not I would try another t-con.
            I assume no responsibility for any stupid suggestions I might post.

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              #7
              Re: Insignia NS58DF620NA20 - have backlight but no picture

              Any luck? I have a similar issue. I switched tcot boards but no luck. I check power at tcot and get 12v. I suspect the lcd panel but don't know how to check for sure.

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                #8
                Re: Insignia NS58DF620NA20 - have backlight but no picture

                If one side at a time does not produce an image, it is worth trying to replace the tcon.

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                  #9
                  Re: Insignia NS58DF620NA20 - have backlight but no picture

                  Just an update on this.

                  - I tried a replacement T-Con and it did not fix the problem.
                  - I tried 3 replacement main boards and they did not fix the problem.

                  At this point I'm thinking the main board is not the problem since 3 replacement boards all exhibited the same problem (I could see 1 replacement being bad, but not 3). So now I'm thinking either 1) I got a bad replacement T-Con, or 2) The panel itself is hosed.

                  I noticed when the TV is powering on, there's a green LED on the T-Con that flashes on for a brief moment and then stays off.
                  Thoughts?

                  Comment

                    #10
                    Re: Insignia NS58DF620NA20 - have backlight but no picture

                    Originally posted by Daveleone View Post
                    Just an update on this.

                    - I tried a replacement T-Con and it did not fix the problem.
                    - I tried 3 replacement main boards and they did not fix the problem.

                    At this point I'm thinking the main board is not the problem since 3 replacement boards all exhibited the same problem (I could see 1 replacement being bad, but not 3). So now I'm thinking either 1) I got a bad replacement T-Con, or 2) The panel itself is hosed.

                    I noticed when the TV is powering on, there's a green LED on the T-Con that flashes on for a brief moment and then stays off.
                    Thoughts?
                    screen 1/2 white with left ribbon disconnected likely suggest left panel edge board is problem location. A few different options

                    - Cut a 10mm wide thin paper to block off some t-con pins. Try different locations on the left ribbon connector and see if get partial image.

                    - Inspect the gold color edge board to panel flex and the the long narrow chip soldered onto it for any damage.

                    - Check the left panel edge boards caps for shorts.

                    - Probe some voltages on the left panel edge board with and without left ribbon connected. See whats different and give you a source to search.

                    In general, you want to see VGH (15-30v) VGL (-7 to -15v) VADD (7-15v) voltages. These voltages are specific to the panel but generally in these range. If you don't see any voltage like this, there is likely some short pulling them down.

                    Fixed an LG with sound, backlight, no image recently. Post #18 is an outline of the process. Need to dig into panel edge boards if t-con+main aren't the issues (you've tried 2 boards with same symptom)

                    https://www.badcaps.net/forum/showthread.php?t=116761

                    Comment

                      #11
                      Re: Insignia NS58DF620NA20 - have backlight but no picture

                      Maybe it needs firmware update/pair, as is the case many times when the mainboard and tcon are not changed with a matching set.

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