Samsung 2253bw black screen

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  • BigDaddyAdy
    Member
    • Jan 2014
    • 14
    • Romania

    #61
    Re: Samsung 2253bw black screen

    Yes, the image is there, only the invertor is not working.

    Comment

    • selldoor
      Slow Learner
      • Dec 2010
      • 7870

      #62
      Re: Samsung 2253bw black screen

      Does your board have the small green torpedo fuse is it good and what is the voltage on it relative to a ground screw.

      What are the part numbers of the inverter transformers - have you tested them?
      Please upload pictures using attachment function when ask for help on the repair
      http://www.badcaps.net/forum/showthread.php?t=39740

      Comment

      • budm
        Badcaps Legend
        • Feb 2010
        • 40746
        • USA

        #63
        Re: Samsung 2253bw black screen

        Is the BL_ON (ON/OFF) signal still present when the backlights go out?
        12-PIN connector
        1- b-dim
        2- 13v
        3- gnd
        4- gnd
        5- 5.1v
        6- 5.1v
        7- a-dim
        8- on/off
        9- 3.3v
        10- led
        11- key 1
        12- key 2
        Last edited by budm; 01-07-2014, 04:54 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

        • BigDaddyAdy
          Member
          • Jan 2014
          • 14
          • Romania

          #64
          Re: Samsung 2253bw black screen

          The fuse is good, the voltage is 13.6V.
          The Bl_On Goes to 4.5V if i remember correctly, i will have to check again in the morning.

          Comment

          • budm
            Badcaps Legend
            • Feb 2010
            • 40746
            • USA

            #65
            Re: Samsung 2253bw black screen

            If I were you, I will use two test lamps to verify if it is the board problem or the lamps problem. Can we see the top side of the board to see if the ballast caps look OK or not, also you should check the high voltage winding of both inverter transformers.
            https://www.badcaps.net/forum/showthread.php?t=19987
            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

            • BigDaddyAdy
              Member
              • Jan 2014
              • 14
              • Romania

              #66
              Re: Samsung 2253bw black screen

              The lamps are ok.
              As i told you, there is a problem with OVP (over voltage protection) circuit. One smd resistor and one smd capacitor look damaged and i can't identify their values. Could anyone give me their values or give me a schematic so i can change them?

              Comment

              • budm
                Badcaps Legend
                • Feb 2010
                • 40746
                • USA

                #67
                Re: Samsung 2253bw black screen

                If you can get the P/N of that PWM IC, then you may be able to tell what the function of that resistor and the cap are for.
                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

                • budm
                  Badcaps Legend
                  • Feb 2010
                  • 40746
                  • USA

                  #68
                  Re: Samsung 2253bw black screen

                  You can contact the jahjhai of this thread also.
                  https://www.badcaps.net/forum/showthread.php?t=20459
                  Last edited by budm; 01-08-2014, 11:33 AM.
                  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

                  • domy_os
                    New Member
                    • Jan 2015
                    • 6
                    • Croatia

                    #69
                    Re: Samsung 2253bw black screen

                    Hi,

                    I have faulty 2233BW monitor and would like to repair the PSU board rather then buy the new one. Capacitors looks good but I changed them with low ESR models and problem is still here. After switching monitor on, CCFL works for about few seconds, then turns off. I can see the picture with flashlight and I hear some squeaking from board. I did some readings while monitor was turned on:

                    Resistance on inverter secondary trafo: around 1100 Ohm
                    Voltage on inverter primary trafo: 0 V
                    Resistance between MOSFET pins: I could't measure it with my meter, scale was on 2 MOhm and it showed up just number 1
                    Voltage between F301 fuse and ground: around 14.6 V

                    I have only basic experience with servicing electronics. Can you help me? What's wrong with PSU board? Thank you.

                    Comment

                    • budm
                      Badcaps Legend
                      • Feb 2010
                      • 40746
                      • USA

                      #70
                      Re: Samsung 2253bw black screen

                      https://www.badcaps.net/forum/showthread.php?t=19987
                      I would test the board with two test lamps to eliminate the possibility that you may have bad lamp/lamps, or bad wiring on the lamps.
                      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

                      • selldoor
                        Slow Learner
                        • Dec 2010
                        • 7870

                        #71
                        Re: Samsung 2253bw black screen

                        Originally posted by domy_os
                        Hi,

                        Resistance on inverter secondary trafo: around 1100 Ohm
                        You should have two reading and they need to be exact - not "around"
                        Please upload pictures using attachment function when ask for help on the repair
                        http://www.badcaps.net/forum/showthread.php?t=39740

                        Comment

                        • domy_os
                          New Member
                          • Jan 2015
                          • 6
                          • Croatia

                          #72
                          Re: Samsung 2253bw black screen

                          I use LED and tungsten bulbs in my apartment so I don't have such lamps but will try to find it somewhere.

                          What can I do next until I get some CFL lamp?

                          Comment

                          • domy_os
                            New Member
                            • Jan 2015
                            • 6
                            • Croatia

                            #73
                            Re: Samsung 2253bw black screen

                            Sorry, I can't edit above post.

                            Originally posted by selldoor
                            You should have two reading and they need to be exact - not "around"
                            Resistance on first trafo: 1060 Ohm
                            Resistance on second trafo: 1111 Ohm

                            Comment

                            • selldoor
                              Slow Learner
                              • Dec 2010
                              • 7870

                              #74
                              Re: Samsung 2253bw black screen

                              That looks like your problem- they should be within 3% - what is the number on the
                              transformer/s
                              Please upload pictures using attachment function when ask for help on the repair
                              http://www.badcaps.net/forum/showthread.php?t=39740

                              Comment

                              • domy_os
                                New Member
                                • Jan 2015
                                • 6
                                • Croatia

                                #75
                                Re: Samsung 2253bw black screen

                                TM-21240. I made a few pictures with old caps...

                                EDIT: Deleted Dropbox link and photos uploaded as attachment.
                                Attached Files
                                Last edited by domy_os; 01-27-2015, 03:10 PM.

                                Comment

                                • selldoor
                                  Slow Learner
                                  • Dec 2010
                                  • 7870

                                  #76
                                  Re: Samsung 2253bw black screen

                                  Please can you repost the pictures using manage attachments so they
                                  remain with the thread to help others.
                                  Please upload pictures using attachment function when ask for help on the repair
                                  http://www.badcaps.net/forum/showthread.php?t=39740

                                  Comment

                                  • domy_os
                                    New Member
                                    • Jan 2015
                                    • 6
                                    • Croatia

                                    #77
                                    Re: Samsung 2253bw black screen

                                    So, I have to replace inverter trafos? I found one on eBay but it's too expensive. The new PSU board costs less then one pair of trafos. Is there any alternative part number?

                                    Comment

                                    • selldoor
                                      Slow Learner
                                      • Dec 2010
                                      • 7870

                                      #78
                                      Re: Samsung 2253bw black screen

                                      I dont think there will be an alternative - perhaps wait and see if any more
                                      input and if you can get a cfl bulb for budm's tester. It could be that on a high resistance one the 3% can stretch to 5% . I cant find what it should be but I note on lcdparts.net at the top of the inverter section it says 10%!! which is a bit freaky as we have fixed many sets that have been just over 3% by advisng to change the transformer.

                                      EDIT perhaps message the ebay seller and ask if they can tell you the value of the secondary
                                      resistance.
                                      Last edited by selldoor; 01-27-2015, 03:45 PM.
                                      Please upload pictures using attachment function when ask for help on the repair
                                      http://www.badcaps.net/forum/showthread.php?t=39740

                                      Comment

                                      • ilsinho
                                        New Member
                                        • Jan 2015
                                        • 1
                                        • Deutschland

                                        #79
                                        Re: Samsung 2253bw black screen

                                        Secondary resistence should be around 1380 ohm.

                                        Comment

                                        • Rtech
                                          Badcaps Legend
                                          • Jul 2010
                                          • 1095

                                          #80
                                          Re: Samsung 2253bw black screen

                                          My experience with Inverter transformers,is that the 3% supposed error limit is certainly not sacrsanct !! I have seen many with more than 5% which were not faulty,and others approaching the 10% also.However Samsung ones do seem to fail at the lower levels,for whatever reason,and in various of their Models it is a standard fault...is this one of the Monitors that has the latter ??

                                          Comment

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