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Samsung 2253BW - 2 Sec to Black issue

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    Samsung 2253BW - 2 Sec to Black issue

    Hi all,

    I recently purchased 2 faulty Samsung 2253BW monitor with the aim of fixing them both seeing as i successfully repaired my Samsung 19" TV. I've successfully repaired one of the 2253BW already by replacing the fuse (F301) and bad caps (C301 & C302) but i'm having trouble with the other one.

    So far i've replaced:

    C301 (820uf 25v)
    C302 (820uf 25v)
    C108 (820uf 25v)
    C112 (820uf 25v)
    C115 (1000uf 16v)
    C116 (1000uf 16v)
    C119 (330uf 10v)
    C107 (47uf 50v)
    F301 (125v 4a)

    But still the screen comes on for 2 seconds and then off. Also, there is a high pitched noise which changes when the screen is switched off and on. Seems to be coming from around LF101 (near the power plug). Not sure if this is a red herring tho.

    I know the screen panel is good as I've used a good power board on it and it displays fine.

    Picture of the power board below:





    Any suggestions welcomed.

    Thanks for you replies in advanced.

    Cheers
    Adam

    #2
    Re: Samsung 2253BW - 2 Sec to Black issue

    There are two SMD 8-PIN MOSFETs which drives the HV Inverter transformer, that section got very hot as you can see the board has burnt mark, you need to check them. Can you read the number as printed on top of the MOSFETs?
    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


      #3
      Re: Samsung 2253BW - 2 Sec to Black issue

      Thanks, i think it reads "STM8309 81343"

      Any idea how i would go about test that component ?

      Comment


        #4
        Re: Samsung 2253BW - 2 Sec to Black issue

        Need to look up the spec sheet to get the pin out of the Gate, Drian, and Source of the MOSFET so you check the resistance of those pins in combination.

        S to D
        S to G
        G to D
        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


          #5
          Re: Samsung 2253BW - 2 Sec to Black issue

          http://pdf1.alldatasheet.com/datashe...P/STM8309.html

          Any idea of the range of read outs i should be seeing ?

          S1 to D1 (both) - 341k
          S2 to D2 (both) - 337k
          S1 to G1 - 421k
          S2 to G2 - 10k
          G1 to D1 (both) - 0.815m
          G2 to D2 (both) - 345k

          Comment


            #6
            Re: Samsung 2253BW - 2 Sec to Black issue

            They are not shorted out or has low Ohm readings, so looks OK.
            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


              #7
              Re: Samsung 2253BW - 2 Sec to Black issue

              Actually, the only one that has a off reading compared to the others is the 2nd chip and S2 to G2, its reading is 5.7

              Does that look like my problem ?

              Comment


                #8
                Re: Samsung 2253BW - 2 Sec to Black issue

                If it reads 5.7 Ohms, that is bad, and since you also had blown the fuse that feed the voltage to the MOSFETS something was shorted. You may want to check the fuse again.
                Last edited by budm; 08-28-2013, 11:50 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


                  #9
                  Re: Samsung 2253BW - 2 Sec to Black issue

                  I'm trying to match up a replacement MOSFET but i'm not sure which one.... http://uk.rs-online.com/web/c/semico...ock=4294957913

                  I've filtered the required spec according to the spec sheet and got it down to 2, but which one ? Of course these might not be compatible.

                  Or these 2: http://uk.rs-online.com/web/c/semico...ock=4294957828

                  Cheers,
                  Adam
                  Last edited by AdamJ; 08-28-2013, 02:26 PM.

                  Comment


                    #10
                    Re: Samsung 2253BW - 2 Sec to Black issue

                    The pin out have to match.
                    Voltage and Current handling has to be the same or higher, not lower.
                    RdsON should be really close or lower, slightly higher will be OK (it will run hotter with higher RdsON). Vgs in the same range. Same or higher power dissipation.
                    DMC3028LSD is really close, it should work.
                    Last edited by budm; 08-28-2013, 02:47 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


                      #11
                      Re: Samsung 2253BW - 2 Sec to Black issue

                      I've managed to get a STM8309, its on its way.

                      Looks like its going to be very difficult to swap this out, its so tiny !

                      Comment


                        #12
                        Re: Samsung 2253BW - 2 Sec to Black issue

                        One thing to do,is to add solder,before unsoldering.

                        Comment


                          #13
                          Re: Samsung 2253BW - 2 Sec to Black issue

                          That's an easy swap really. RTech's suggestion of adding more solder first is a good one.

                          Cut he pins close to the chip with a sharp knife first. You only need to remove one pin at a time then and there's less chance of lifting a track with too much heat.

                          Tack each corner pin down of the new chip and then apply liquid no clean flux fluid and drag solder across the pins. If any pins are bridged with solder accidentally, simply apply more liquid flux and drag a clean soldering bit over the pins and the excess solder will come away. Or you can use solder wick to remove excess, whichever you find easiest.

                          HTH

                          Comment


                            #14
                            Re: Samsung 2253BW - 2 Sec to Black issue

                            I hope you order more than 1 MOSFET, I always replace both of them together.
                            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


                              #15
                              Re: Samsung 2253BW - 2 Sec to Black issue

                              Thank you Badcaps !!! Its fixed and working !!

                              Special thanks to budm for his expert input and suggestions !

                              Cheers guys !

                              Comment

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