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    Re: Samsung Syncmaster 245BW

    Thanks, I will check it when I get home.
    I have like five devices opened and it seems that I have difficulty fixing them.
    I need a lot of help. These devices require real diagnosis, not just replacing caps.
    Vizio VO42L won't turn on, Philips 42PFL7422D won't turn on, LG 42LG4270 short(blowing fuse), Asus MK241H still a no go(will return to that in a little bit).
    I still have a 40" Sony which I haven't even opened up yet(4 blinks), no room.

    Comment


      Re: Samsung Syncmaster 245BW

      CLEAR & BIG Photos of the back of your board please.

      Back of board, AC power connection to the right, lower-left 1/4 of board from the transformer to the edge with the 2 connectors.

      T
      veritas odium parit

      Comment


        Re: Samsung Syncmaster 245BW

        The only difference made, when I removed the QB802 transistor.
        The voltage at the 3x68ohm output raised to 24.99V, but I forgot to check the input voltage at the 3x68ohm resistors. Unfortunately one of the caps blew up("hissed" leaked acid) CM863.
        I guess, I shouldn't live the power on for so long with a transistor removed.
        We are getting somewhere, that's good.
        I have checked transistor QB802, and checks out OK.
        I haven't seen anything strange about CP805 or CM811.
        Lifting BB803 didn't make any difference.

        Comment


          Re: Samsung Syncmaster 245BW

          T, I will take those shots in a few.

          Comment


            Re: Samsung Syncmaster 245BW

            Here they are.
            The IC 801S I have changed and I didn't do a "nice job", some of the pads have lifted off, but they make contact.
            Since these pictures I have replaced that capacitor(470uf/35V) and reinstalled QB802 and everything is back on how it was.
            I have measured again the CP805 and it measures 3.3ohm(with or without it).
            Attached Files

            Comment


              Re: Samsung Syncmaster 245BW

              The 68 Ohms resistors feed two voltage regulator transistors. The resistors are getting hot because too much current is flowing, we need to start removing the loads, so it looks like the Q802 is feeding very low resistance load. You should Check the resistance of the IC ICP801S Pin 8 (vcc) and Ground with Emitter of Q802 still not connected.
              CM863 is in parallel with other two 24V filter cap, lifting that Emitter will not kill the cap, otherwise the other two would have blown up aslo. Right now the 24Vdc power supply is working now (should verify that it is putting out 24V, but it may not be since the PFC is not on due to Q802 is not connected) since Q802 and its load is no longer loding down thw output of the 68 Ohms resistors.
              You need to check the output voltage if the transistor regulator out as I have shown.
              Last edited by budm; 08-03-2012, 10:14 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


                Re: Samsung Syncmaster 245BW

                On the emitter of the QB803 I have 1.2V.
                3x68 ohm no change.

                Comment


                  Re: Samsung Syncmaster 245BW

                  That cannot be since you have indicated that one of the cap for the 24v power supply filter cap has blown up, 1.2V will not be enough for the 24v power supply to run. What do you get at the Emitter of Q803 when choke BB803 is lifted. when both Emitter legs of Q802, Q803, there will hardly be any load on the output side of the 68 Ohms. Please recheck your measurement.
                  I need to know what voltage you are getting at the Emitter of both transistors without the load connected.
                  By the what ground point are you using for this Primary AC circuits?
                  Last edited by budm; 08-03-2012, 10:44 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


                    Re: Samsung Syncmaster 245BW

                    sorry, I forgot to add that 1.2V is at the emitter, with the emitter lifted(QB803).

                    Comment


                      Re: Samsung Syncmaster 245BW

                      What voltage do you get at the base of the Q803, especially the voltage on that Zener Diode.
                      What do you get at Emitter of Q802 Collector, Base?
                      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


                        Re: Samsung Syncmaster 245BW

                        I haven't tested the Q802 this way, I have just removed it completely.
                        It's late now, I will do these measurments tomorrow.
                        I have a feeling that something between the two transistors will be the culprit.

                        Comment


                          Re: Samsung Syncmaster 245BW

                          Q802, Q803 circuits without the loads connected to their Emitter will not cause the load down of the supply voltage.
                          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


                            Re: Samsung Syncmaster 245BW

                            Finally I had some time to do these measurements.
                            What I did:
                            removed both transistors and re soldered them on the back of the board with the emitters in the air.
                            QB803
                            C=10-16.5V oscillating
                            B=11.3-17.3V oscillating
                            E=10.5-16.6V oscillating
                            B802
                            C=28V slight oscillation
                            B=16.02V
                            E=16.06V
                            ICP801S's pin #8 and GND= 3.3 Ohm
                            Main cap voltage is oscillating 157-161V

                            Comment


                              Re: Samsung Syncmaster 245BW

                              "QB803
                              C=10-16.5V oscillating
                              B=11.3-17.3V oscillating
                              E=10.5-16.6V oscillating
                              B802
                              C=28V slight oscillation
                              B=16.02V
                              E=16.06V
                              ICP801S's pin #8 and GND= 3.3 Ohm"

                              OK, something is wrong here since Collector of Q802 and Q803 are tied together and connected to 68 Ohm output side, so please check that again, they should have exact same voltage reading.
                              Pin 8 ICP801S reading short circuits, so remove the filter caps on that pin 8 and see if the shorts goes away, otherwise, you have shorted IC.
                              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


                                Re: Samsung Syncmaster 245BW

                                You are right, I will double check my measurements.

                                Comment


                                  Re: Samsung Syncmaster 245BW

                                  Ooops, I have installed 803 backwards.
                                  now I have:
                                  803
                                  C=28V
                                  B=20.69V
                                  E=20.66V

                                  I will have to remove both capacitors, but a bit later today.

                                  Comment


                                    Re: Samsung Syncmaster 245BW

                                    OK, now the output voltages are close to what I have expected from these two regulator transistors.
                                    Now you just have to find out why you have 3.3 Ohms on that pin 8 of the IC.
                                    You are getting close to the cause of the problem.
                                    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


                                      Re: Samsung Syncmaster 245BW

                                      I have just removed the IC and I don't have 3.3 ohms there.
                                      So I'm ordering a new IC.
                                      Thank you very much for your help, without you I wouldn't be able to repair these monitors and TVs.
                                      I still have a couple which needs your or others help.
                                      I have just checked the Asus monitor(burned resistors) and the TA1530A is not getting enough Vcc, only 1.79V.
                                      I still have an LG TV with a short somewhere and a Philips TV that it's dead.
                                      If everything goes well, tomorrow I'm getting my first LED TV, it's a Vizio M420NV. I'm anxious to see how it's inside.
                                      Sorry to be so off topic, but since you are following this repair of this monitor you will read most likely much faster this message.
                                      Could you please send me the diagram or pictures of that short circuit test stand that you have made? I have purchased the components for it, I just need to put them together. Everything is in series?
                                      Last edited by tibimakai; 08-04-2012, 10:56 PM.

                                      Comment


                                        Re: Samsung Syncmaster 245BW

                                        Well that is great news that you have found the shorts, you will get better and better as you begin to understand how the circuits work, just take time, I am still learning and trying to understand how things work everyday.
                                        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


                                          Re: Samsung Syncmaster 245BW

                                          http://s807.photobucket.com/albums/y...t=DSC01679.jpg

                                          http://s807.photobucket.com/albums/y...t=DSC01681.jpg
                                          Yes, just the lamp in series with the line side of the outlet.
                                          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

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