Sansui 55" LCD TV Model STY1655 (Backlights switching off intermittently)

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  • angelos
    Badcaps Veteran
    • Dec 2012
    • 568
    • South Africa
    #1

    Sansui 55" LCD TV Model STY1655 (Backlights switching off intermittently)

    Hi guys,
    I have been battling on this one quite some time without any solution. At this point i suspect the inverter board is bad but need to confirm it first. What is happening is that the backlight switch off randomly. I noticed that its the one side of the edge lit leds that flicker and switch off te other side is perfectly fine and stable. I then measured the incoming voltage going off of the LED supply connector and get 42V DC but at times this value changes goes up to 52V. I also measured the return voltage on the LEDs marked N1, N2, N3 etc and they all increase in voltage going up towards 20V DC. Normally they run at about 1.8V Can this be a LED strip going open circuit causing this or is this a bad inverter board?
    What tests can i do to determine this?

    Regards
    Angelos
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    • angelos
      Badcaps Veteran
      • Dec 2012
      • 568
      • South Africa
      #2
      Re: Sansui 55" LCD TV Model STY1655 (Backlights switching off intermittently)

      I see that the Vizio E322MV uses the backlight inverter model number T87D106.00
      Anybody got a schematic for this board? It would really help me.

        Comment

        • CapLeaker
          Leaking Member
          • Dec 2014
          • 8126
          • Canada
          #3
          Re: Sansui 55" LCD TV Model STY1655 (Backlights switching off intermittently)

          Try turning the back lights down as low as they go in the menu and see if the problem goes away or the back lights are staying on for longer. If you do see an improvement with this, you have bad LED's on the back light strips. The panel needs to be taken apart and the strips replaced.

            Comment

            • angelos
              Badcaps Veteran
              • Dec 2012
              • 568
              • South Africa
              #4
              Re: Sansui 55" LCD TV Model STY1655 (Backlights switching off intermittently)

              There is no such menu option. What i can do, is swap the two plugs around and see if it's the inverter or the led's. The problem is that the plugs differ so i will have to remove the individual wires and swap over after marking the wires. Risky but can prove its the backlights or not.

                Comment

                • angelos
                  Badcaps Veteran
                  • Dec 2012
                  • 568
                  • South Africa
                  #5
                  Re: Sansui 55" LCD TV Model STY1655 (Backlights switching off intermittently)

                  Update: I swapped the two led plugs around to find out that the same side is flickering thus its the inverter that's faulty.

                    Comment

                    • angelos
                      Badcaps Veteran
                      • Dec 2012
                      • 568
                      • South Africa
                      #6
                      Re: Sansui 55" LCD TV Model STY1655 (Backlights switching off intermittently)

                      I meant to say its the leds on that side that are faulty. You agree?

                        Comment

                        • CapLeaker
                          Leaking Member
                          • Dec 2014
                          • 8126
                          • Canada
                          #7
                          Re: Sansui 55" LCD TV Model STY1655 (Backlights switching off intermittently)

                          yes, the LEDs on that side is / are faulty. These LED's are constant current driven, not by constant voltage. That's why you see the volts go up when a LED goes out.

                            Comment

                            • angelos
                              Badcaps Veteran
                              • Dec 2012
                              • 568
                              • South Africa
                              #8
                              Re: Sansui 55" LCD TV Model STY1655 (Backlights switching off intermittently)

                              Thanks Capleaker, i have ordered replacement LED's. Will have to wait 4 months to arrive. That's how pathetic our postal service is here in South Africa.
                              Will post a update once i have installed them.

                                Comment

                                • CapLeaker
                                  Leaking Member
                                  • Dec 2014
                                  • 8126
                                  • Canada
                                  #9
                                  Re: Sansui 55" LCD TV Model STY1655 (Backlights switching off intermittently)

                                  yeah... sometimes it isn't much better here either with 3 months.

                                    Comment

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