hisense f42k20e no backlight

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  • mattstolte
    Badcaps Veteran
    • Dec 2013
    • 612
    • usa

    #1

    hisense f42k20e no backlight

    I got this set the led lights red when I press power it goes blue but no backlights. all the voltages on the power supply are correct. the only thing im trying to determine if it is bad led strip or main? the bl/dim have 3.3 and 5v and then this lines going to the backlights the top + has 132.00v and the other 2nd + has none

    Attached Files
  • budm
    Badcaps Legend
    • Feb 2010
    • 40746
    • USA

    #2
    Re: hisense f42k20e no backlight

    How about the pictures of the whole backside of the TV and the whole boards?
    Turn the TV off then have the probe attached to the TOP + (PIN 1) keep an eye on the DCV meter when turn on the TV to see if the Voltage goes higher than 132VDC.
    Then do the same again WITHOUT the LED connector in place, report the reading.
    It looks like the two LED strings are connected in series to form one big string.
    Last edited by budm; 09-10-2015, 02:13 PM.
    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

    • mattstolte
      Badcaps Veteran
      • Dec 2013
      • 612
      • usa

      #3
      Re: hisense f42k20e no backlight

      yes bud will get some tomorrow thanks. is there suppose to be no voltage on the bottom 2+ ?

      Comment

      • budm
        Badcaps Legend
        • Feb 2010
        • 40746
        • USA

        #4
        Re: hisense f42k20e no backlight

        If the LED strings are connected in series, so if the first string is open then the other strings will not have any current flow through them to develop the Voltage drops on the other LED string.
        Looking at you board, I would say it only has two LED strings and they are connected in series.
        I expect the DCV on the connector to jump to > 200VDC when you first turn on the TV and then drops down to lower Voltage.
        Last edited by budm; 09-11-2015, 09:24 PM.
        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

        • mattstolte
          Badcaps Veteran
          • Dec 2013
          • 612
          • usa

          #5
          Re: hisense f42k20e no backlight

          BUD the voltages do not change

          Attached Files

          Comment

          • budm
            Badcaps Legend
            • Feb 2010
            • 40746
            • USA

            #6
            Re: hisense f42k20e no backlight

            So it shows 132VDC when the power switch is activated and it did not jump higher that that at all?
            BTW, if you have the LED connector hooked back up and you get no DCV at all on the 2+ pin, that will indicate that the +1 string has open circuit.
            Last edited by budm; 09-14-2015, 01:47 PM.
            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

            • mattstolte
              Badcaps Veteran
              • Dec 2013
              • 612
              • usa

              #7
              Re: hisense f42k20e no backlight

              Yes none are line 2

              Comment

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