Barco LCN-42 No Power

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  • Jasgriff
    Badcaps Veteran
    • Feb 2012
    • 578
    • UK

    #61
    Re: Barco LCN-42 No Power

    I have found some PNP transistors with 100 Vceo but i'm struggling to find a 100ma one?

    Farnell.co.uk

    Would one of these do? Looking at your diagram I will need 1 NPN and 1 PNP.
    Fixed so far : 1 Home cinema system, 16 LCD Monitors, 4 LCD TV's

    How to resize your pictures guide click HERE
    Retiredcaps Ideal post example click HERE

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    • budm
      Badcaps Legend
      • Feb 2010
      • 40746
      • USA

      #62
      Re: Barco LCN-42 No Power

      Most power supply works the same way, if you understand the basic, then when you trace out the connection on something you have not seen before, then it will make sense to you how it works, I hope I explain it well. When the SMPS goes high, it will turn on Q201 which will supply the VCC (12~15VDC? to the Gate of the MOSFET to turn it on), when it goes low, Q201 will turn off, Q202 will turn on and will discharge the internal Gate capacitor (insulation) inside the MOSFET to make sure it stops conducting ASAP (when it is told to turn off) due to charge remain on the Gate insulation, most circuit will use Diode for this function. This ON and OFF happens at very high speed, 50~100KHz, depends on circuits design.
      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

        #63
        Re: Barco LCN-42 No Power

        The NPN Q201 check OK right? What is the current rating? Higher rating is 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

        • Jasgriff
          Badcaps Veteran
          • Feb 2012
          • 578
          • UK

          #64
          Re: Barco LCN-42 No Power

          Originally posted by budm
          The NPN Q201 check OK right? What is the current rating? Higher rating is OK.
          Ahh i was worried that the rating was the draw? but its just the maximum that it can with stand.

          Both Transistors are broken.

          How about these 2?

          http://www.diodes.com/zetex/_pdfs/3.0/pdf/FMMT593.pdf

          http://www.farnell.com/datasheets/302332.pdf
          Last edited by Jasgriff; 03-19-2012, 05:01 PM.
          Fixed so far : 1 Home cinema system, 16 LCD Monitors, 4 LCD TV's

          How to resize your pictures guide click HERE
          Retiredcaps Ideal post example click HERE

          Comment

          • budm
            Badcaps Legend
            • Feb 2010
            • 40746
            • USA

            #65
            Re: Barco LCN-42 No Power

            They will be fine, just make sure to not mix up the PNP, NPN when you install them.
            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

            • popeye
              Senior Member
              • May 2011
              • 155

              #66
              Re: Barco LCN-42 No Power

              Make sure you resolder all the DJ's I can see a lot of them.

              Comment

              • Jasgriff
                Badcaps Veteran
                • Feb 2012
                • 578
                • UK

                #67
                Re: Barco LCN-42 No Power

                Originally posted by popeye
                Make sure you resolder all the DJ's I can see a lot of them.
                Disc Jockeys or bad solder joints?
                Fixed so far : 1 Home cinema system, 16 LCD Monitors, 4 LCD TV's

                How to resize your pictures guide click HERE
                Retiredcaps Ideal post example click HERE

                Comment

                • Jasgriff
                  Badcaps Veteran
                  • Feb 2012
                  • 578
                  • UK

                  #68
                  Re: Barco LCN-42 No Power

                  Originally posted by Jasgriff
                  Quick update on where I am at with this one.

                  Ordered some 1 Watt 0.22 OHM metal film resistors and 3 Watt 0.22 OHM wire wound resistors. 1 to replace the blown and the others for spares.

                  Ordered a batch of T8AH fuses in case the board blows another.

                  Ordered the replacement Power Mosfet 11N80C3

                  Ordered some 33k SMD resistors to replace the 2 blown ones that connect to the transistors.

                  Ordered a bottle of Isopropyl Alcohol for getting rid of the flux and gunk.
                  Quick update....

                  The 3 Watt resistors came before the 1 Watt ones so I fitted one of those.

                  The power Mosfet has arrived and been fitted.

                  The Fuses have arrived

                  The Isopropyl Alcohol arrived and I gave the connections a good clean all around.

                  The transistors have been ordered today along with some caps to start replacing those too.

                  I'm going to go over those poor solder joints not to make sure that they dont cause any issue.
                  Fixed so far : 1 Home cinema system, 16 LCD Monitors, 4 LCD TV's

                  How to resize your pictures guide click HERE
                  Retiredcaps Ideal post example click HERE

                  Comment

                  • budm
                    Badcaps Legend
                    • Feb 2010
                    • 40746
                    • USA

                    #69
                    Re: Barco LCN-42 No Power

                    I still have a feeling that the SMPS IC may be damaged also due the fact that the resistors and the transistors are damaged also.
                    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

                    • Jasgriff
                      Badcaps Veteran
                      • Feb 2012
                      • 578
                      • UK

                      #70
                      Re: Barco LCN-42 No Power

                      Originally posted by budm
                      I still have a feeling that the SMPS IC may be damaged also due the fact that the resistors and the transistors are damaged also.
                      Will it cause any more damage if I try?
                      Fixed so far : 1 Home cinema system, 16 LCD Monitors, 4 LCD TV's

                      How to resize your pictures guide click HERE
                      Retiredcaps Ideal post example click HERE

                      Comment

                      • budm
                        Badcaps Legend
                        • Feb 2010
                        • 40746
                        • USA

                        #71
                        Re: Barco LCN-42 No Power

                        If the SMPS IC is not putting the pulses to switch the MOSFET on and off but stuck with steady High output, the MOSFET will be fully on, and that can damage the MOSFET and the transformer.
                        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

                        • tom66
                          EVs Rule
                          • Apr 2011
                          • 32560
                          • UK

                          #72
                          Re: Barco LCN-42 No Power

                          It will also blow the fuse and could damage the PFC diode and bridge rectifier in rare circumstances.
                          Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
                          For service manual, schematic, boardview (board view), datasheet, cad - use our search.

                          Comment

                          • Jasgriff
                            Badcaps Veteran
                            • Feb 2012
                            • 578
                            • UK

                            #73
                            Re: Barco LCN-42 No Power

                            So you would both change the IC rather than giving it a try?

                            I knew what your answers would have been so I have removed that IC also.

                            I did lift the pad on pin 7 this pin is not used luckily! It also looks like Pin 8 HV is not connected to anything, not sure if its an optional thing?

                            http://www.datasheetcatalog.org/data...swapill4cy.pdf

                            Ok had to order them from the US so I guess I will have to wait a few extra days to see if it fires up
                            Last edited by Jasgriff; 03-20-2012, 11:31 AM.
                            Fixed so far : 1 Home cinema system, 16 LCD Monitors, 4 LCD TV's

                            How to resize your pictures guide click HERE
                            Retiredcaps Ideal post example click HERE

                            Comment

                            • budm
                              Badcaps Legend
                              • Feb 2010
                              • 40746
                              • USA

                              #74
                              Re: Barco LCN-42 No Power

                              Yes I would have replaced it than taking a chance of blowing up new parts and caused more damages.
                              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

                              • Jasgriff
                                Badcaps Veteran
                                • Feb 2012
                                • 578
                                • UK

                                #75
                                Re: Barco LCN-42 No Power

                                Well hopefully I will have a new one here on Friday
                                Fixed so far : 1 Home cinema system, 16 LCD Monitors, 4 LCD TV's

                                How to resize your pictures guide click HERE
                                Retiredcaps Ideal post example click HERE

                                Comment

                                • budm
                                  Badcaps Legend
                                  • Feb 2010
                                  • 40746
                                  • USA

                                  #76
                                  Re: Barco LCN-42 No Power

                                  Crossing my fingers that I got the digram correct per what I could see from the pictures, long distant troubleshooting is not easy, that is why real good pictures come in to play.
                                  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

                                  • Jasgriff
                                    Badcaps Veteran
                                    • Feb 2012
                                    • 578
                                    • UK

                                    #77
                                    Re: Barco LCN-42 No Power

                                    Well I have ordered 4 mosfets 3 chips 10 resistors and seven fuses so I have a few spares to try out.

                                    I can imagine its difficult working things out when its not in front of you.

                                    Here is another one of the board that I took to show you which parts provide which voltages.
                                    Attached Files
                                    Fixed so far : 1 Home cinema system, 16 LCD Monitors, 4 LCD TV's

                                    How to resize your pictures guide click HERE
                                    Retiredcaps Ideal post example click HERE

                                    Comment

                                    • Jasgriff
                                      Badcaps Veteran
                                      • Feb 2012
                                      • 578
                                      • UK

                                      #78
                                      Re: Barco LCN-42 No Power

                                      3K SMD's have turned up today and they have been fitted.

                                      So just waiting for the SMPS and the transistors then we are ready to go.
                                      Fixed so far : 1 Home cinema system, 16 LCD Monitors, 4 LCD TV's

                                      How to resize your pictures guide click HERE
                                      Retiredcaps Ideal post example click HERE

                                      Comment

                                      • budm
                                        Badcaps Legend
                                        • Feb 2010
                                        • 40746
                                        • USA

                                        #79
                                        Re: Barco LCN-42 No Power

                                        Can't wait!
                                        Is it 3k or 30k?
                                        30k in post #57
                                        Last edited by budm; 03-21-2012, 03:41 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

                                        • Jasgriff
                                          Badcaps Veteran
                                          • Feb 2012
                                          • 578
                                          • UK

                                          #80
                                          Re: Barco LCN-42 No Power

                                          Originally posted by budm
                                          Can't wait!
                                          Is it 3k or 30k?
                                          30k in post #57
                                          Yeah 30k sorry.

                                          Wont get the SMPS until Monday unfortunately.
                                          Fixed so far : 1 Home cinema system, 16 LCD Monitors, 4 LCD TV's

                                          How to resize your pictures guide click HERE
                                          Retiredcaps Ideal post example click HERE

                                          Comment

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