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Sony Bravia KDL-42EX440 - problem - turns off after switching on

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    #21
    Re: Sony Bravia KDL-42EX440 - problem - turns off after switching on

    my way to do any edge LED back light by replace them all
    1- with hot air gun from the down side of the strips heat them and took all out
    2- with shave plate scratch the LED strips more from right side and left side
    3 place solder on the old place and the new scratch with iron
    4- replace the new LED in place with finger press it at its place then with iron i heat the solder outside the LED, it will mild all solder of one side and the led i can feel it pressed down a little. same way to opposite side.

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      #22
      Re: Sony Bravia KDL-42EX440 - problem - turns off after switching on

      can you post photo of yours LED Back light socket on PSU .. ?

      you said each strip had 56 LED, this huge if they are not separated as groups. to be sure if they are 6 or 3 volts

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        #23
        Re: Sony Bravia KDL-42EX440 - problem - turns off after switching on

        Yes it is 56 LEDs in series per strip (one group).
        I tried LEDs with 3V at fIrst but I could not get them to shine.
        After that I tested LEDs with 6V, all LEDs are shining except 5 LEDs which are bad.
        I expected one LED to be bad. How come 5 LEDs were open connection?

        On PSU there are two connectors for LED back-light. Two pins per connector.
        Photos attached.
        Attached Files
        Last edited by zarko; 03-22-2019, 07:01 PM.

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          #24
          Re: Sony Bravia KDL-42EX440 - problem - turns off after switching on

          Originally posted by zarko View Post
          Yes it is 56 LEDs in series per strip (one group).
          I tried LEDs with 3V at fIrst but I could not get them to shine.
          After that I tested LEDs with 6V, all LEDs are shining except 5 LEDs which are bad.
          I expected one LED to be bad. How come 5 LEDs were open connection?

          On PSU there are two connectors for LED back-light. Two pins per connector.
          Photos attached.
          what are the label reading of the 2 caps near back light socket on PSU ?

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            #25
            Re: Sony Bravia KDL-42EX440 - problem - turns off after switching on

            Both caps are 10uF, 450V.

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              #26
              Re: Sony Bravia KDL-42EX440 - problem - turns off after switching on

              I have analysed those 4020 LEDs that are working fine.

              This is what I measured:
              Voltage applied:___| 5.5V | 5.75V | 6.00V | 6.2V
              Measured current:_| 20mA | 40mA | 60mA | 80mA
              Measured current is nor exactly the same for all LEDs, this is average value.

              I am thinking of switching to 2835 LEDs.
              I have found this LED in a local store but I am not sure if it would be suitable for LCD TV usage.
              https://store.comet.rs/Catalogue/Product/48222/
              Last edited by zarko; 03-25-2019, 06:51 PM.

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                #27
                Re: Sony Bravia KDL-42EX440 - problem - turns off after switching on

                you are going with this thinking to damage the strips and it may cause damage your PSU. stay on original 4020

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                  #28
                  Re: Sony Bravia KDL-42EX440 - problem - turns off after switching on

                  Originally posted by zarko View Post
                  I am thinking of switching to 2835 LEDs.
                  I have found this LED in a local store but I am not sure if it would be suitable for LCD TV usage.
                  https://store.comet.rs/Catalogue/Product/48222/
                  I wouldn't change the LED dimensions on an edge lit TV. The LEDs were chosen for a reason. They reflect their light down the inside of the acrylic sheet on edge lit TVs. Changing the LED width will upset those reflections.

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                    #29
                    Re: Sony Bravia KDL-42EX440 - problem - turns off after switching on

                    Thank you Diah & diif.
                    I will stay with 4020.
                    I guess it is Aliexpress then.

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                      #30
                      Re: Sony Bravia KDL-42EX440 - problem - turns off after switching on

                      I’m sorry for my bad English because is not my first language, but I want to know if you resolved the problem. I have the same issue on the same tv model and I want to be sure if it’s the led strips that are bad so I can order a new one and replace it.

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                        #31
                        Re: Sony Bravia KDL-42EX440 - problem - turns off after switching on

                        Hello Elviscocho,
                        Yes, I resolved the issue. Problem was in the led strips.

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