Rca led50b45rq

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  • x_orange90_x
    Badcaps Veteran
    • May 2015
    • 702
    • USA

    #81
    Re: Rca led50b45rq

    I will check those pins tonight. However, i think i may have overlooked a very possible sign of failure.. I was going back through the pictures i posted earlier this week and found a great deal of discoloration around the resistors on the bottom of the board (picture reattached). From what I've read about this model, it doesn't usually run hot, so could this be a possible sign that the resistors are blown?
    Attached Files

    Comment

    • x_orange90_x
      Badcaps Veteran
      • May 2015
      • 702
      • USA

      #82
      Re: Rca led50b45rq

      Sorry for the delayed feedback. Here are the readings from the IC. I didn't have time to write the corresponding names out for each pin, so please refer to the attached picture.

      1 - 0
      2 - 0
      3 - .49
      4 - 0
      5 - 0
      6 - 0
      7 - .62
      8 - 0
      9 - 0
      10 - 0
      11 - 0
      12 - .28
      13 - 0
      14 - 0
      15 - .22 drop to 0
      16 - .11 drop to 0
      Attached Files

      Comment

      • x_orange90_x
        Badcaps Veteran
        • May 2015
        • 702
        • USA

        #83
        Re: Rca led50b45rq

        I finally got enough time to type this back out with the corresponding labels.

        CSS - 0V
        DELAY - 0V
        CF - 0.49V
        RFmin - 0V
        STBY - 0V
        ISEN - 0V
        LINE - 0.62V
        DIS - 0V
        PFC_STOP - 0V
        GND - 0V
        LVG - 0V
        Vcc- 0.28V
        N.C. - 0V
        OUT - 0V
        HVG - 0.22V spike, drops to 0V
        VBOOT - 0.11V spike, drops to 0V

        Comment

        • dick_barton
          Badcaps Legend
          • Aug 2015
          • 6642
          • Wales

          #84
          Re: Rca led50b45rq

          The first thing to note is that VCC is at 0.28V so this chip will not operate. Need to find out why there is no voltage supplying VCC

          Are you certain that you have taken the readings with the set switched on and the black meter lead connected to the EC1 / EC1A ground.
          Last edited by dick_barton; 03-27-2017, 10:11 AM.
          Willing to help but I'm no expert.

          Comment

          • x_orange90_x
            Badcaps Veteran
            • May 2015
            • 702
            • USA

            #85
            Re: Rca led50b45rq

            Set was out of standby (ON), and black probe was on the negative leg of EC1.

            Comment

            • x_orange90_x
              Badcaps Veteran
              • May 2015
              • 702
              • USA

              #86
              Re: Rca led50b45rq

              Am i possibly checking this incorrectly? The lack of replies has me wondering if I've either stumped the experts, or just hit a dead end. This leads me to ask if the grounds behind the power board screws are a determining factor Here, because i am checking these voltages with the board breadboarded..

              Comment

              • budm
                Badcaps Legend
                • Feb 2010
                • 40746
                • USA

                #87
                Re: Rca led50b45rq

                Originally posted by x_orange90_x
                Am i possibly checking this incorrectly? The lack of replies has me wondering if I've either stumped the experts, or just hit a dead end. This leads me to ask if the grounds behind the power board screws are a determining factor Here, because i am checking these voltages with the board breadboarded..
                Right now you will have to trace out the connection from the VCC pin of the PFC IC back to the switched power supply source which means reverse engineering the board, so how much time are you willing to spend to do that? I do not have the board in front of me to do that at this point.
                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

                • x_orange90_x
                  Badcaps Veteran
                  • May 2015
                  • 702
                  • USA

                  #88
                  Re: Rca led50b45rq

                  I will look closer at it tonight and try to follow the trace. Hopefully I'll get lucky and it lead back to a capacitor. I'm assuming that the VCC is one of the most crucial points of the power supply system?

                  Comment

                  • budm
                    Badcaps Legend
                    • Feb 2010
                    • 40746
                    • USA

                    #89
                    Re: Rca led50b45rq

                    No VCC no running circuit, just like no battery to run your cell phone.
                    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

                      #90
                      Re: Rca led50b45rq

                      We are going to need real hi res straight shot pictures of the top and bottom side of the board without all that glare so we can easily see the traces.
                      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

                      • x_orange90_x
                        Badcaps Veteran
                        • May 2015
                        • 702
                        • USA

                        #91
                        Re: Rca led50b45rq

                        Here is the best i could do without creating a glare again.

                        Edit: I added a couple more pictures with light shining through the board from both sides. PIN 12 (VCC) is the pin that lines up exactly with the left side of C4 (fourth pin from the right).
                        Attached Files
                        Last edited by x_orange90_x; 03-31-2017, 04:31 PM.

                        Comment

                        • budm
                          Badcaps Legend
                          • Feb 2010
                          • 40746
                          • USA

                          #92
                          Re: Rca led50b45rq

                          Check DCV at Collector of Q10.
                          Attached Files
                          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

                          • x_orange90_x
                            Badcaps Veteran
                            • May 2015
                            • 702
                            • USA

                            #93
                            Re: Rca led50b45rq

                            Thank you for the diagram! Do i just need to check the points you've labeled + and -?

                            Comment

                            • vinceroger69
                              Badcaps Legend
                              • Mar 2012
                              • 6714
                              • uk

                              #94
                              Re: Rca led50b45rq

                              q10 budm has maked check the dc voltage on the pin marked c thats the collector pin.

                              Comment

                              • x_orange90_x
                                Badcaps Veteran
                                • May 2015
                                • 702
                                • USA

                                #95
                                Re: Rca led50b45rq

                                Originally posted by vinceroger69
                                q10 budm has maked check the dc voltage on the pin marked c thats the collector pin.
                                Am i putting the black probe on the - pin he marked as HGND and the red probe on that C pin? I really am trying to keep up with this, however my experience with electronics diagnostics has never went this in depth. I am completely willing to learn though and rather excited to be doing this.
                                Last edited by x_orange90_x; 04-01-2017, 06:02 AM.

                                Comment

                                • vinceroger69
                                  Badcaps Legend
                                  • Mar 2012
                                  • 6714
                                  • uk

                                  #96
                                  Re: Rca led50b45rq

                                  yes i would test it that way myself just be carefull as thats the hot/mains live side of the psu so dont let probes etc slip as may cause more damage

                                  Comment

                                  • budm
                                    Badcaps Legend
                                    • Feb 2010
                                    • 40746
                                    • USA

                                    #97
                                    Re: Rca led50b45rq

                                    Originally posted by x_orange90_x
                                    Am i putting the black probe on the - pin he marked as HGND and the red probe on that C pin? I really am trying to keep up with this, however my experience with electronics diagnostics has never went this in depth. I am completely willing to learn though and rather excited to be doing this.
                                    Black probe on HGND (HOT SIDE CIRCUIT GND), just be real careful since you are working in the deadly side of the circuit, best to at least plug the TV into the GFCI outlets.
                                    E = Emitter
                                    B = Base
                                    C = Collector
                                    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

                                    • x_orange90_x
                                      Badcaps Veteran
                                      • May 2015
                                      • 702
                                      • USA

                                      #98
                                      Re: Rca led50b45rq

                                      Originally posted by budm
                                      Black probe on HGND (HOT SIDE CIRCUIT GND), just be real careful since you are working in the deadly side of the circuit, best to at least plug the TV into the GFCI outlets.
                                      E = Emitter
                                      B = Base
                                      C = Collector

                                      Here are those voltages:

                                      B - 13.5v
                                      C - 14v
                                      E - 12.97v

                                      Comment

                                      • budm
                                        Badcaps Legend
                                        • Feb 2010
                                        • 40746
                                        • USA

                                        #99
                                        Re: Rca led50b45rq

                                        Originally posted by x_orange90_x
                                        Here are those voltages:

                                        B - 13.5v
                                        C - 14v
                                        E - 12.97v
                                        So that Q10 Emitter has about 13VDC, but you are getting only 0.28V ON PIN 12 of the PFC IC.
                                        As you can see in the picture that I marked, the E is conected ZERO resistor, another end of that resistor should be connected to pin 12 where C4 is also, so verify if my tracing is correct or not. It should show <1 Ohms between pin 12 of the IC and the Emitter/ or the resistor connected to the Emitter of Q10.
                                        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

                                        • x_orange90_x
                                          Badcaps Veteran
                                          • May 2015
                                          • 702
                                          • USA

                                          #100
                                          Re: Rca led50b45rq

                                          Your tracing appears correct. I checked resistance between the resistor 000 and pin 12, from 000 to both sides of C4, and also from the incoming side of 000 to both ends of C4 and to pin 12. I get a reading of 1 with all of them, however a couple of times i had it bounce all around from 70.0 and below when checking the incoming side of 000 to the outgoing side of C4.

                                          Comment

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