LG Flatron EW224 - No backlight

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  • mattpd
    Badcaps Veteran
    • Oct 2012
    • 301
    • USA

    #1

    LG Flatron EW224 - No backlight

    I have a EW224 Flatron monitor that shows a display, but does not have a back light. This model is has an LED back light. Luckily for me, I have a working version of the exact same monitor, so I swapped the power and logic board into the dead monitor, but still I have no back light. The only conclusion that I can make is that the LEDs themselves are faulty.

    I have replaced CCFLs in monitors before, but never LEDs. Is there anything I need to look for when I crack open the LCD screen? Is it a simple job to replace LEDs, or is it not worth the time?
  • budm
    Badcaps Legend
    • Feb 2010
    • 40746
    • USA

    #2
    Re: LG Flatron EW224 - No backlight

    The y use the very delicate FFC (Flat Flexible Cable) that can easily be cut or nicked into and cause it to short out to the chassis. Since the LEDs are connected in series, if one is open then the rest will not light up. So those are some of the thing to look for, you can try measuring each of the conductor pad on the FFC and the chassis to see if any one of them is shorted to the chassis. You also have working unit that you can do some resistance reading comparison.
    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

    • mattpd
      Badcaps Veteran
      • Oct 2012
      • 301
      • USA

      #3
      Re: LG Flatron EW224 - No backlight

      Thanks, I will crack it open tomorrow and take a look

      Comment

      • Iceman2
        New Member
        • Oct 2012
        • 5
        • Poland

        #4
        Re: LG Flatron EW224 - No backlight

        Hi guys I have problem, i buy this monitor and in the power board there is missing
        C303( i dont know the value and voltage:/ The number for board is EAX63028703/0 and version HIGH. Meaby you have service manual or know values

        Comment

        • lexwalker
          Badcaps Veteran
          • Feb 2011
          • 307
          • Malaysia

          #5
          Re: LG Flatron EW224 - No backlight

          Originally posted by Iceman2
          Hi guys I have problem, i buy this monitor and in the power board there is missing
          C303( i dont know the value and voltage:/ The number for board is EAX63028703/0 and version HIGH. Meaby you have service manual or know values
          Is this a working monitor when you bought it? Pictures of the area around that C303 capacitor, as well as description of the circuit leading to C303 capacitor (possibly a partial schematic) may help us guess. Sometimes there are empty spots where the manufacturer simply changed their minds at the last moment and decided not to put a component there..

          Comment

          • Iceman2
            New Member
            • Oct 2012
            • 5
            • Poland

            #6
            Re: LG Flatron EW224 - No backlight

            I buy the monitor for repair and when i dissasemply i see that someone desolder the C303 and other capacitors meaby for test, solder the rest but no the 303. Monitor is dead when i buy, no led power I check the mosfet 18T10GH and is shorted, C303 is connected to that 18T10GH with positive leg

            Comment

            • lexwalker
              Badcaps Veteran
              • Feb 2011
              • 307
              • Malaysia

              #7
              Re: LG Flatron EW224 - No backlight

              Originally posted by Iceman2
              I buy the monitor for repair and when i dissasemply i see that someone desolder the C303 and other capacitors meaby for test, solder the rest but no the 303. Monitor is dead when i buy, no led power I check the mosfet 18T10GH and is shorted, C303 is connected to that 18T10GH with positive leg
              Not good enough description. Please post pictures of that area. If possible, some partial (self-drawn) schematics as well. Is that capacitor surface mount type, or through hole type? Is this MOSFET in the inverter section?

              Comment

              • Iceman2
                New Member
                • Oct 2012
                • 5
                • Poland

                #8
                Re: LG Flatron EW224 - No backlight

                No the capacitor is normal through hole Electrolytic Capacitor, Su'scon shit The mosfet is connected to the led driver mp3399ey, this is led screen. I check all components in the upper layer, capacitos,diodes... all ok
                Attached Files

                Comment

                • selldoor
                  Slow Learner
                  • Dec 2010
                  • 7870

                  #9
                  Re: LG Flatron EW224 - No backlight

                  Does it look like Q300 has been removed also.?

                  Looks like a big mosfet?
                  http://mlb-s1-p.mlstatic.com/placa-f...9_032013-O.jpg


                  and lots of other components
                  Last edited by selldoor; 08-02-2014, 05:10 AM.
                  Please upload pictures using attachment function when ask for help on the repair
                  http://www.badcaps.net/forum/showthread.php?t=39740

                  Comment

                  • lexwalker
                    Badcaps Veteran
                    • Feb 2011
                    • 307
                    • Malaysia

                    #10
                    Re: LG Flatron EW224 - No backlight

                    Originally posted by Iceman2
                    No the capacitor is normal through hole Electrolytic Capacitor, Su'scon shit The mosfet is connected to the led driver mp3399ey, this is led screen. I check all components in the upper layer, capacitos,diodes... all ok
                    Looks like part of a boost converter, with that inductor/choke then followed by a rectifier diode. Could be anywhere from 4.7uf to 47uF (or higher). The voltage rating for that capacitor could be at least 100Vdc (and higher). According to MP3399EY datasheet sample schematics, its 22uF 100VDC although the inductor used was 33uH (while this board looks to be using 47uH)...

                    Comment

                    • Iceman2
                      New Member
                      • Oct 2012
                      • 5
                      • Poland

                      #11
                      Re: LG Flatron EW224 - No backlight

                      I remove the Q300 mosfet, test it and is shorted i upload the pictures after remove yup the inductor/choke is 47uH i test and is 45uH The diode is good I dont have that capacitor value, if i have i test the board replacing for good brand I emai a guy who sell identical board on ebay, the picture is above and i dont see the values

                      Comment

                      • Iceman2
                        New Member
                        • Oct 2012
                        • 5
                        • Poland

                        #12
                        Re: LG Flatron EW224 - No backlight

                        Originally posted by Iceman2
                        I remove the Q300 mosfet, test it and is shorted i upload the pictures after remove yup the inductor/choke is 47uH i test and is 45uH The diode is good I dont have that capacitor value, if i have i test the board replacing for good brand I emai a guy who sell identical board on ebay, the picture is above and i dont see the values

                        update:

                        Hi guys i repair that monitor, the capacitor is 100V 47uf, 5v is stable

                        Comment

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