Rca led50b45rq

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  • budm
    Badcaps Legend
    • Feb 2010
    • 40746
    • USA

    #101
    Re: Rca led50b45rq

    Originally posted by x_orange90_x
    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.
    "from 000 to both sides of C4" what kind of resistance it showing on the meter 0 Ohms to both side of C4?
    We need to know if the resistance is in OHM, K OHM , or M OHM.
    Since you have 12V at BOTH end of that '000' OHMS resistor and it has connection to pin 12 of the IC then it is impossible to get 0.28V as you report earlier. You have to think logically at this point when it does not make sense based on your DATA, or error in your measurement. Point 'A' has 12V and is connected DIRECTLY to point 'B' so it is impposible not to have 12v at point 'B'.
    Last edited by budm; 04-02-2017, 01:34 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

    • x_orange90_x
      Badcaps Veteran
      • May 2015
      • 702
      • USA

      #102
      Re: Rca led50b45rq

      I checked with the lowest resistance setting on my multimeter 200 (see attached picture). All that displayed was a 1 all the way to the left of the display.
      Attached Files
      Last edited by x_orange90_x; 04-02-2017, 03:58 PM.

      Comment

      • vinceroger69
        Badcaps Legend
        • Mar 2012
        • 6714
        • uk

        #103
        Re: Rca led50b45rq

        as some of these readings do seem a little odd maybe put a new battery in your multi meter as maybe a little low also test a brand new battery and check it reads the correct dc votage on your meter as in the past we have seen multi meters give odd/false readings.

        Comment

        • budm
          Badcaps Legend
          • Feb 2010
          • 40746
          • USA

          #104
          Re: Rca led50b45rq

          Originally posted by x_orange90_x
          I checked with the lowest resistance setting on my multimeter 200 (see attached picture). All that displayed was a 1 all the way to the left of the display.
          That means it is more than 200 Ohms, your meter is showing over range.
          Just touch the two probes together and see what you get and that is what you should get when you measure the resistance from 000 resistor to pin 12 of the 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

          • dick_barton
            Badcaps Legend
            • Aug 2015
            • 6642
            • Wales

            #105
            Re: Rca led50b45rq

            I checked with the lowest resistance setting on my multimeter 200 (see attached picture). All that displayed was a 1 all the way to the left of the display.
            This should help you.

            https://www.youtube.com/watch?v=nPdECcBU1Vc
            Last edited by dick_barton; 04-02-2017, 04:54 PM.
            Willing to help but I'm no expert.

            Comment

            • x_orange90_x
              Badcaps Veteran
              • May 2015
              • 702
              • USA

              #106
              Re: Rca led50b45rq

              I just checked again using the 2000k setting. I got the same 1 reading that fluctuates for a couple seconds and drops to 000. That is from either side of the 000 resistor to the out-going side of C4 (the side just before pin 12). Once i got the same result directly to pin 12, but following attempts left me with the 1 to the left.

              Comment

              • budm
                Badcaps Legend
                • Feb 2010
                • 40746
                • USA

                #107
                Re: Rca led50b45rq

                Stay with 200 Ohm scale, we need to see <1 Ohms or so resistance when tracing the direct connection between point 'A' and point 'B'.
                We need to find out what that end of 000 resistor is connected to.
                That VCC pin 12 of that IC should have direct connection to Emitter/or Collector of the switched transistor some where on the board, just a matter of finding it.
                Last edited by budm; 04-02-2017, 09:05 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

                • x_orange90_x
                  Badcaps Veteran
                  • May 2015
                  • 702
                  • USA

                  #108
                  Re: Rca led50b45rq

                  Originally posted by budm
                  We need to find out what that end of 000 resistor is connected to. That VCC pin 12 of that IC should have direct connection to Emitter/or Collector of the switched transistor some where on the board, just a matter of finding it.
                  Check out the attached pictures and let me know what you think.
                  Attached Files

                  Comment

                  • budm
                    Badcaps Legend
                    • Feb 2010
                    • 40746
                    • USA

                    #109
                    Re: Rca led50b45rq

                    https://www.badcaps.net/forum/attach...0&d=1491216069
                    So pin 12 goes to the EMITTER of Q13? That section is for the current sensing of the for the Power MOSFET that drives the transformer.
                    I think you need to find out which pin of the IC is connected to the 0 Ohms resistor, I can only see the trace going the IC but cannot tell unless you Ohm it out..
                    BTW, are you sure about the P/N of that 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

                    • x_orange90_x
                      Badcaps Veteran
                      • May 2015
                      • 702
                      • USA

                      #110
                      Re: Rca led50b45rq

                      I shared that picture and tracing with you because it *looked* as though it may go that route. I can clearly see a trace going under C4 and over to Q13.. But i don't really know what I'm looking at. That's why i wanted to share it with you. The P/N is L6599AD. I downloaded the Spec sheet for it in order to get the Pin-out.

                      Comment

                      • budm
                        Badcaps Legend
                        • Feb 2010
                        • 40746
                        • USA

                        #111
                        Re: Rca led50b45rq

                        At this point I would put one probe on the 000 resistor and another probe on each pin of the IC to see which pin will show <1 Ohm resistance, meter in 200 Ohm scale.
                        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

                          #112
                          Re: Rca led50b45rq

                          I will check them all tonight. I suppose it's possible that I've got the diagram backwards, but unlikely because of the orientation of the text. This chip doesn't have a little dot indicating pin 1. Instead it has a little triangle logo. However, i read that if there are no clear markings for pin 1, then with the text right side up Pin 1 would be the lower left pin.

                          So what reading should i expect to find in the correct situation?

                          Comment

                          • dick_barton
                            Badcaps Legend
                            • Aug 2015
                            • 6642
                            • Wales

                            #113
                            Re: Rca led50b45rq

                            Post a photo of the IC to help identify pin 1
                            Willing to help but I'm no expert.

                            Comment

                            • x_orange90_x
                              Badcaps Veteran
                              • May 2015
                              • 702
                              • USA

                              #114
                              Re: Rca led50b45rq

                              Originally posted by dick_barton
                              Post a photo of the IC to help identify pin 1
                              If you google an image of this chip, some of them do have an indicator hole located in that bottom left corner.
                              Attached Files

                              Comment

                              • dick_barton
                                Badcaps Legend
                                • Aug 2015
                                • 6642
                                • Wales

                                #115
                                Re: Rca led50b45rq

                                Is there a chamfer down the left hand side of the IC looking at the photo you've just posted?
                                Willing to help but I'm no expert.

                                Comment

                                • x_orange90_x
                                  Badcaps Veteran
                                  • May 2015
                                  • 702
                                  • USA

                                  #116
                                  Re: Rca led50b45rq

                                  The attached picture is from the other side of the chip.. No chamfer
                                  Attached Files

                                  Comment

                                  • dick_barton
                                    Badcaps Legend
                                    • Aug 2015
                                    • 6642
                                    • Wales

                                    #117
                                    Re: Rca led50b45rq

                                    Is there a chamfer down the left hand side of the IC looking at the photo you've just posted if not then it looks like as you have already numbered.

                                    http://wb5rvz.org/common/locatingPin1
                                    Willing to help but I'm no expert.

                                    Comment

                                    • vinceroger69
                                      Badcaps Legend
                                      • Mar 2012
                                      • 6714
                                      • uk

                                      #118
                                      Re: Rca led50b45rq

                                      i have fitted one of these ics a while ago and fitted it thinking bottom left was pin 1 the psu worked fine so must of been correct

                                      Comment

                                      • budm
                                        Badcaps Legend
                                        • Feb 2010
                                        • 40746
                                        • USA

                                        #119
                                        Re: Rca led50b45rq

                                        If I am correct one of that IC pin should have direct connection between the two points. That switched Voltage source has to used for something.
                                        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

                                          #120
                                          Re: Rca led50b45rq

                                          Originally posted by budm
                                          If I am correct one of that IC pin should have direct connection between the two points. That switched Voltage source has to used for something.
                                          OK.. I think I've finally got what you're looking for. Between PIN 12 (yes, the one we've referred to the entire time) and that point you marked (which i believe is C5 capacitor on the other side), i got 1.4-13 on the 200 scale. ALSO, this time between the out going side of resistor 000 and PIN 12, i got 5.7-195 on the 200 scale.

                                          Comment

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