LG w2241s 2sec and then black

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  • rippergr
    Badcaps Veteran
    • May 2014
    • 345
    • Ελλάδα

    #1

    LG w2241s 2sec and then black

    Hello,
    this is my first post (and repair try) for an lcd screen except bad caps.
    I have an LG W2241S that when I turn it on it stays on for 2-4 seconds and then goes to black.
    I checked for bad caps , all seems fine, I put good lamps it does exactly the same.
    Can someone tell me where to start looking and how and what to measure.
    I am attaching a few pictures from the lcd.
    Thanks in advance.
    Attached Files
  • rippergr
    Badcaps Veteran
    • May 2014
    • 345
    • Ελλάδα

    #2
    Re: LG w2241s 2sec and then black

    P.S. I try with one new lamp at a time. Same problem.
    The transformer in the secondary winding has 1011 ohm one one side and 1024 ohm on the other side.
    Primary winding shows 000 ohm ( not open )

    Comment

    • budm
      Badcaps Legend
      • Feb 2010
      • 40746
      • USA

      #3
      Re: LG w2241s 2sec and then black

      You should use two test lamps at a time since you can have two bad lamps in one lamp assembly.
      I.E.
      http://s807.photobucket.com/user/bud...ml?sort=3&o=11
      http://s807.photobucket.com/user/bud...ml?sort=3&o=10
      http://s807.photobucket.com/user/bud...ml?sort=3&o=32
      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

      • rippergr
        Badcaps Veteran
        • May 2014
        • 345
        • Ελλάδα

        #4
        Re: LG w2241s 2sec and then black

        I first try with two new lamps.
        Then I used one good lamp only and no second lamp.

        Comment

        • bammbammfran
          Badcaps Veteran
          • Apr 2014
          • 476
          • USA

          #5
          Re: LG w2241s 2sec and then black

          usually not all 4 bulbs will go bad at one time , but ??
          You do need 4 working bulbs for it to stay on
          to try to figure out if it is bad bottom or bad top bulbs:
          you need to use two new lamps on the bottom two plugs and put two old top lamps into the top two plugs and try it.
          and if that does not stay on, install the two new ones into the top two plugs and the 2 used bottom ones into the bottom two plugs
          if your new bulbs do not at least flash on on the top 2 or the bottom 2 , then the transformer might be bad.

          Comment

          • budm
            Badcaps Legend
            • Feb 2010
            • 40746
            • USA

            #6
            Re: LG w2241s 2sec and then black

            Originally posted by rippergr
            I first try with two new lamps.
            Then I used one good lamp only and no second lamp.
            How did you go about testing using the two lamps and one lamp only?
            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

            • rippergr
              Badcaps Veteran
              • May 2014
              • 345
              • Ελλάδα

              #7
              Re: LG w2241s 2sec and then black

              When I say one lamp I mean one pair of lamps
              I have attached a picture.
              So I test it with 4 new lamps (2 pairs) and it does the same problem.
              Attached Files

              Comment

              • selldoor
                Slow Learner
                • Dec 2010
                • 7870

                #8
                Re: LG w2241s 2sec and then black

                Looking at the picture of the back of the board the soldering on at least one
                pin of the transformer looks suspect.
                As it seemed to resistance test ok I would reflow all the joints on the inverter transformer,
                and while you are in there reflow all the blue high voltage caps as well.
                Attached Files
                Last edited by selldoor; 07-09-2014, 02:44 AM.
                Please upload pictures using attachment function when ask for help on the repair
                http://www.badcaps.net/forum/showthread.php?t=39740

                Comment

                • rippergr
                  Badcaps Veteran
                  • May 2014
                  • 345
                  • Ελλάδα

                  #9
                  Re: LG w2241s 2sec and then black

                  Originally posted by selldoor
                  Looking at the picture of the back of the board the soldering on at least one
                  pin of the transformer looks suspect.
                  As it seemed to resistance test ok I would reflow all the joints on the inverter transformer,
                  and while you are in there reflow all the blue high voltage caps as well.
                  This is just soldering paste. I reflowed all the joints in transformer and in all blue caps but still the same problem

                  Comment

                  • budm
                    Badcaps Legend
                    • Feb 2010
                    • 40746
                    • USA

                    #10
                    Re: LG w2241s 2sec and then black

                    OK, there are two SMD Duld MOSFETS (4 legs on the bottom and big tab on top) that drive the inverter transformer, please get the numbers and look up the spec sheet.
                    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

                    • rippergr
                      Badcaps Veteran
                      • May 2014
                      • 345
                      • Ελλάδα

                      #11
                      Re: LG w2241s 2sec and then black

                      Originally posted by budm
                      OK, there are two SMD Duld MOSFETS (4 legs on the bottom and big tab on top) that drive the inverter transformer, please get the numbers and look up the spec sheet.
                      You mean those 2 MOSFETS?
                      Sorry but I am newbie

                      p.s: those mosfets are APM4048D WJC3V
                      I found that the specs are here http://www.anpec.com.tw/ashx_prod_fi...APM4048DU4.pdf
                      Can you tell me how to check?
                      Thanks
                      Attached Files
                      Last edited by rippergr; 07-09-2014, 12:54 PM.

                      Comment

                      • budm
                        Badcaps Legend
                        • Feb 2010
                        • 40746
                        • USA

                        #12
                        Re: LG w2241s 2sec and then black

                        Yes.
                        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

                        • rippergr
                          Badcaps Veteran
                          • May 2014
                          • 345
                          • Ελλάδα

                          #13
                          Re: LG w2241s 2sec and then black

                          Can you tell me how to test the MOSFETS?
                          Do I have to unsolder them or I can measure them on circuit?

                          Comment

                          • selldoor
                            Slow Learner
                            • Dec 2010
                            • 7870

                            #14
                            Re: LG w2241s 2sec and then black

                            If you have 2 seconds to black you should read this
                            https://www.badcaps.net/forum/showthread.php?t=10419

                            start at post 19. There is a section on testing mosfets.

                            First you just test them for shorts so you can do that on the board
                            with NO power to the board.

                            If you get stuck ask again - if you understand it, post your results.
                            Please upload pictures using attachment function when ask for help on the repair
                            http://www.badcaps.net/forum/showthread.php?t=39740

                            Comment

                            • cdicky
                              Member
                              • Jul 2014
                              • 27
                              • England

                              #15
                              Re: LG w2241s 2sec and then black

                              Sorting my tv out a few weeks back, i found a lingk on youtube showing the lamp good circuit for each lamp. Some sort of nandgate. If the current (voltage) goes too high it shuts off supply to inverters. Spent weeks sorting mine out, from psu caps to swapping inverters. But even after all that still tripped to black after few seconds.

                              Eventually after testing everything and loads of 'repairs' 'it HAD to work and was back together and on the wall. Could have cried when it just went again.
                              So thought F** IT. And just kept turning it back off/on with standby button as soon as screen went off.
                              Funnily enough after about 60 times, (was better than throwing remote at it) I decided this thing was gonna either fry or work. And eventually heard a large crackle and sizzel.
                              So did it a few more times and guess what, damd thing has worked fine ever since.

                              And my verdict? well initial faults were poor psu no doubt. But all that handling and moving (big TV) just made things lose. Face down it worked Ok after repairs, but on the wall it would die and go black again.
                              Until it had a good supply to work with I reckon it arced over one of the lamp contacts, and when it did so welded a poor connection.

                              So rather than replace all the lamps, give that a look.
                              And good luck

                              Comment

                              • rippergr
                                Badcaps Veteran
                                • May 2014
                                • 345
                                • Ελλάδα

                                #16
                                Re: LG w2241s 2sec and then black

                                I think it's the MOSFET.
                                I test it based on selldoor post.
                                With my multimeter on 200 ohms I checked
                                Black S1 - Red G1 = infinitive
                                Black S1 - Red D1 = sometimes increase value to infinitive , sometimes infinitive
                                Black G1 - Red D1 = infinitive

                                Black S2 - Red G2 = infinitive
                                Black S2 - Red D2 = infinitive
                                Black G2 - Red D2 = infinitive

                                The second MOSFET doesnt clearly show values . sometimes show some ohms and go to infinitive

                                Comment

                                • selldoor
                                  Slow Learner
                                  • Dec 2010
                                  • 7870

                                  #17
                                  Re: LG w2241s 2sec and then black

                                  They actually look ok to me as long as there are no readings less than 30 ohms
                                  it suggests they are ok. I will try and think of some other tests hopefully Budm will look in a again later
                                  Please upload pictures using attachment function when ask for help on the repair
                                  http://www.badcaps.net/forum/showthread.php?t=39740

                                  Comment

                                  • vinceroger69
                                    Badcaps Legend
                                    • Mar 2012
                                    • 6714
                                    • uk

                                    #18
                                    Re: LG w2241s 2sec and then black

                                    whats the part number on the inverter transformer?

                                    Comment

                                    • rippergr
                                      Badcaps Veteran
                                      • May 2014
                                      • 345
                                      • Ελλάδα

                                      #19
                                      Re: LG w2241s 2sec and then black

                                      its not very clear. The numbers I see are EBJ5753( some numbers under a sticker)
                                      right under that eel-220
                                      right under TC 0844

                                      Comment

                                      • vinceroger69
                                        Badcaps Legend
                                        • Mar 2012
                                        • 6714
                                        • uk

                                        #20
                                        Re: LG w2241s 2sec and then black

                                        are these numbers off the picture post 1 the black oblong transformer top off picture?

                                        Comment

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