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    Vizio M470NV Backlight

    Alright, so I just picked up a Vizio M470NV TV sitting outside that someone left behind thinking "All hope is lost". I however am much more optimistic and figured it was something simple such as maybe a fuse.

    The problem I am having is with the backlighting.
    When turning the lights off I can see the picture while shining a light on to the screen. I also have no issues with sound. It seems that the only issue is with the backlights.

    What I'm asking for is some assistance in pointing me into the right direction on where I can find the fuse for the LED power supply to find out of that's the issue or if I need to search deeper into the strips themselves? I'm hoping someone in the community has had experience with this TV.


    -Thanks!

    #2
    Re: Vizio M470NV Backlight

    We are trying to figure the same thing out on my Vizio LED edge. I will let you know when we have a conclusion

    Comment


      #3
      Re: Vizio M470NV Backlight

      I've just messed with a M470.
      The power supply should connect to a smaller LED driver board. There may be a smd fuse on that.

      Also check the voltages coming from the psu to driver board and I believe there was also a ribbon from the main to the driver board; you can check that as well.

      If for some reason you conclude its the actual strips (rare in my opinion), I do have those. (Though mine wasn't a NV).
      Last edited by drpj23; 11-08-2012, 07:13 PM.

      Comment


        #4
        Re: Vizio M470NV Backlight

        Edit - Typo'd

        Comment


          #5
          Re: Vizio M470NV Backlight

          @XmouseX, I wonder if his board use that 540N regulator IC, if it does, then we ask him to take the voltage reading at the output pin for us!
          Never mind, his board is way different than yours.
          Last edited by budm; 11-08-2012, 07:54 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


            #6
            Re: Vizio M470NV Backlight

            I had a Vizio 47 inch lcd with the same symptoms. There were 2 bad caps and one blown small surface mount fuse on the inverter board

            Comment


              #7
              Re: Vizio M470NV Backlight

              You can disconnect the wires that go the the LED String assembly which are connected to the two blue connectors, per printed on the circuit board, it should have 145Vdc output, be careful not to slip the probe!
              http://www.shopjimmy.com/vizio-0500-...upply-unit.htm
              There are white connectors on the bottom row, look for BL_ON PIN and see if it has >3VDC on it, that pin is used for turning backlights ON/OFF, ON = >3vdc.
              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


                #8
                Re: Vizio M470NV Backlight

                @budm - On the blue connectors, my readings across the pins are:
                VLED: 114v
                4-1: 12v
                4-2: 10v
                4-3: 12v
                The voltages are the same for the other 3 "groups"

                As far as the white connectors, they all have the proper voltages as well as the BL_ON pin is >3VDC

                Comment


                  #9
                  Re: Vizio M470NV Backlight

                  BL_ON pin is >3VDC is good and it is turning on the power supply for the LED OK. So connected the LEDs cables back in and see if you will still have the 114V.
                  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


                    #10
                    Re: Vizio M470NV Backlight

                    Sorry, that was with the cables connected.

                    Comment


                      #11
                      Re: Vizio M470NV Backlight

                      4-1: 12v
                      4-2: 10v
                      4-3: 12v

                      I will need to figure out what these voltage readings mean.
                      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


                        #12
                        Re: Vizio M470NV Backlight

                        I have a feeling it is something with the LED backlights themselves and not necessarily a power issue. I don't think that voltage drop is the problem because it's pretty consistent throughout the plugs.

                        Comment


                          #13
                          Re: Vizio M470NV Backlight

                          4-1: 12v
                          4-2: 10v
                          4-3: 12v
                          The example of the voltage readings are done at the LED return connectors, you do have the VLED feeding the LED strings OK, the voltage on the return lines just do not look right. Need to see how they do the current control of the LED strings.
                          Can you look and see how those 4-1,4-2, etc are connected?
                          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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