TCL 55s405 no backlight

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  • speter
    Been around the
    • Dec 2009
    • 77
    • USA

    #1

    TCL 55s405 no backlight

    I have a TCL 55s405 TV with the back light out, there 4 wires to the backlight(pic to follow) I would like to test the led strips without taking the set apart
    How can I find out the proper voltage to power the strips?
    So far I cannot find service info on the set.
    I have sound, and picture with a flashlight
    Attached Files
    Last edited by speter; 11-04-2020, 06:32 PM.
    Goshen NY, USA
  • Diah
    Badcaps Legend
    • Feb 2013
    • 6355
    • Germany

    #2
    Re: TCL 55s405 no backlight

    be brave and ask friends to help you take the screen apart. you can spend money and waiting time of led tester.. but of sure you will need the asking of friends help. this advice free of charge

    Comment

    • budm
      Badcaps Legend
      • Feb 2010
      • 40746
      • USA

      #3
      Re: TCL 55s405 no backlight

      Originally posted by speter
      I have a TCL 55s405 TV with the back light out, there 4 wires to the backlight(pic to follow) I would like to test the led strips without taking the set apart
      How can I find out the proper voltage to power the strips?
      So far I cannot find service info on the set.
      I have sound, and picture with a flashlight
      Show us the pictures of the whole backside of the TV so we can see what we are dealing with.
      Also good clear straight shots of the power supply/LED driver board.
      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

      • speter
        Been around the
        • Dec 2009
        • 77
        • USA

        #4
        Re: TCL 55s405 no backlight

        I figure it's pretty hard to measure the voltage out to the LED strips, because the PS shuts down very fast, so I can easily power the strips from the connector, and see if it's the leds light, or power supply is bad.
        I hear you about dismantling the panel
        Attached Files
        Goshen NY, USA

        Comment

        • budm
          Badcaps Legend
          • Feb 2010
          • 40746
          • USA

          #5
          Re: TCL 55s405 no backlight

          OK, you have 4 wires for the LED's.
          1) TV is off, set Volt meter to 200VDC scale, all connectors in place.
          2) Keep black probe of the meter on the chassis.
          3) Keep red probe on one of the 4 pin of the LED connector.
          4) Turn on the TV while watching the meter to see how high the Voltage jumps up to before it goes into shout down, then turn off the TV and wait 10 seconds.
          5) Repeat the same test on the other 3 wires.
          6) Report the result of each test.
          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

          • speter
            Been around the
            • Dec 2009
            • 77
            • USA

            #6
            Re: TCL 55s405 no backlight

            Top wire (black) goes to 200 -300 volts (my meter is pretty slow) Pin 9
            Second wire(red) always 0 Pin 7
            Third wire (white)always 0 Pin 4
            Bottom wire(red) goes to 40 - 65v Pin 2
            Last edited by speter; 11-04-2020, 11:06 PM.
            Goshen NY, USA

            Comment

            • budm
              Badcaps Legend
              • Feb 2010
              • 40746
              • USA

              #7
              Re: TCL 55s405 no backlight

              You have open circuit (bad LED, bad connection between LED strips, bad wires, etc) for the LED current path to complete that is why the Voltage went up to 300V.
              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

              • speter
                Been around the
                • Dec 2009
                • 77
                • USA

                #8
                Re: TCL 55s405 no backlight

                Thank you!
                My daughter smashed our Vizio 55 and I am going through some TVs that a friend gave me, looking for an easy fix for a replacement.
                Tomorrow I'll try a 60 Samsung with no power, sooner or later we will be watching again
                Goshen NY, USA

                Comment

                • nomoresonys
                  Badcaps Legend
                  • Jan 2013
                  • 12093
                  • U.S.

                  #9
                  Re: TCL 55s405 no backlight

                  Yes, break out the sammy, backlight replacement is pretty much the hardest job on tvs.
                  Last edited by nomoresonys; 11-05-2020, 06:45 AM.

                  Comment

                  • speter
                    Been around the
                    • Dec 2009
                    • 77
                    • USA

                    #10
                    Re: TCL 55s405 no backlight

                    The Samsung had shorted LEDs. The set of 2 LED strips came in, but I had to improvise a tester with my bench power supply and a series resistor of 500 ohms to test the strips.
                    I replaced the bad strip, and let the LEDs run a couple of minutes, and put it back together.
                    I put it on the TV stand and it had a small flash of the LEds and it was out again..sigh...
                    I took it apart again, and another string of the same type(4 LED VS 5 LED) so I didn't have the part. I ended up removing 1 good LED from the first bad strip, and installing it on the other bad strip. and the set is working, it has been playing for 6 hours now.
                    Goshen NY, USA

                    Comment

                    • nomoresonys
                      Badcaps Legend
                      • Jan 2013
                      • 12093
                      • U.S.

                      #11
                      Re: TCL 55s405 no backlight

                      Nice work, now turn down the backlights, NOT brightness to as low as you can tolerate, I run my samsung on 8, it goes up to 20 but 20 will wear out your leds much faster.

                      Comment

                      • speter
                        Been around the
                        • Dec 2009
                        • 77
                        • USA

                        #12
                        Re: TCL 55s405 no backlight

                        I can't get into settings yet until the remote arrives tomorrow, watching it through the demo popup for the moment.
                        Goshen NY, USA

                        Comment

                        • nomoresonys
                          Badcaps Legend
                          • Jan 2013
                          • 12093
                          • U.S.

                          #13
                          Re: TCL 55s405 no backlight

                          I operate mine with a 7 dollar philips universal remote, it seems to work every section.

                          Comment

                          • speter
                            Been around the
                            • Dec 2009
                            • 77
                            • USA

                            #14
                            Re: TCL 55s405 no backlight

                            I wasn't sure which universal remote would have all of the functions, so I ordered the one for the TV for about the sane price, If I knew the universal would support every function, I would have gone that way, as this TV could die tomorrow in a worse way
                            Goshen NY, USA

                            Comment

                            • motterpaul
                              Member
                              • Feb 2020
                              • 21
                              • United States

                              #15
                              Re: TCL 55s405 no backlight

                              As long as a universal remote has a "menu" button it should work for your purposes. I found that finding the network helped a lot to getting my Vizio remote up & running again, but there was no "menu" button on the TV. Using an alternate remote "menu" button got the TV remote working again.

                              Comment

                              • speter
                                Been around the
                                • Dec 2009
                                • 77
                                • USA

                                #16
                                Re: TCL 55s405 no backlight

                                TV was good till 3 weeks ago, and it burned out another LED strip, I replaced it, and it is running again. I had already bought a LED kit last time, now I finally was able to put it to use.
                                Goshen NY, USA

                                Comment

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