LG55UK6950PLB backlight but no picture

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  • Chrissygizmo
    Senior Member
    • Mar 2021
    • 108
    • United Kingdom
    #1

    LG55UK6950PLB backlight but no picture

    I've got an LG55UK6950PLB, I have backlights but no picture, I've read about AVDD 17v in another thread on here, I've messed around blocking lines , previously I had only 17v on the left side with the left LVDS connected and 3.9v on the right, now since blocking lines I've got 17v on both sides but no sign of a picture yet.

    I would be grateful for any help as this one is doing its best to psssssi me right off lol
    Tags: None
    • Chrissygizmo
      Senior Member
      • Mar 2021
      • 108
      • United Kingdom
      #2
      Re: LG55UK6950PLB backlight but no picture

      Quick update, I've got a picture now but half of the screen is slightly darker

        Comment

        • notallbad
          Badcaps Legend
          • Oct 2012
          • 1183
          • UK
          #3
          Re: LG55UK6950PLB backlight but no picture

          How did you manage to get a picture?
          Have you checked the tab bonds for obvious damage i.e burnt out?

          Think I had that issue too, screen darker on one side due to tab bond. Was able to get brightness back luckily, believe it was caused by a short.

            Comment

            • Crew
              New Member
              • Jun 2015
              • 4
              • Csongrád
              #4
              Re: LG55UK6950PLB backlight but no picture

              Hi! How could you make it work? I’ve got a TV with the following issue:
              If I remove left cable, I can measure VCC, VDD etc voltages on the right LCD board. If I disconnect right cable, and only left cable is connected, I can not measure any voltage on the left cable.
              More interesting, I tried the “tape fix”. I covered CK lines One by One and all together too, but No changes. Do you have any tip for furthet fixes?

                Comment

                • Crew
                  New Member
                  • Jun 2015
                  • 4
                  • Csongrád
                  #5
                  Re: LG55UK6950PLB backlight but no picture

                  Additional info:

                  If I disconnect the left ribbon I can measure VCC, VDD on the right side, but IC800 is getting very hot. It's an i-2111 J824 IC. What it does? Has anybody info about it?
                  Attached Files

                    Comment

                    • lotas
                      Badcaps Legend
                      • Jan 2016
                      • 4471
                      • Russia
                      #6
                      Re: LG55UK6950PLB backlight but no picture

                      i2111 - High-Current VCOM Drive
                      Op Amps for TFT LCDs (IML2111CL-TR ( MAX9650 = ICN7211 = ANX7011))
                      Attached Files

                        Comment

                        • Crew
                          New Member
                          • Jun 2015
                          • 4
                          • Csongrád
                          #7
                          Re: LG55UK6950PLB backlight but no picture

                          Lotas, thanks the schematics!!!
                          Based on them I could disable the IC800 / i2111.
                          ( removed the resistors before and after this IC. R801, R820 )

                          It seems, that I still have a short on HAVDD line. I removed the big cap from this line ( C806 ), but the short is still there.

                          Do you have any additional tip for the repair?

                            Comment

                            • lotas
                              Badcaps Legend
                              • Jan 2016
                              • 4471
                              • Russia
                              #8
                              Re: LG55UK6950PLB backlight but no picture

                              C807 is also on the same line as C806 (maybe other capacitors located elsewhere, or maybe in the panel itself ...).

                                Comment

                                • Crew
                                  New Member
                                  • Jun 2015
                                  • 4
                                  • Csongrád
                                  #9
                                  Re: LG55UK6950PLB backlight but no picture

                                  It seems that the panel itself is faulty

                                    Comment

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