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Vizio M420NV - No sound, remote not working

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    Vizio M420NV - No sound, remote not working

    My Vizio model m420nv TV recently had the sound go out. I tried to see if I could get sound out of the audio jack, but it didn't work. I switched from the DirectTV box to the DVD player to see if it was an input problem, but it didn't have sound either. After some research, some people reported the audio setting changes in the menu by itself. I tried to check the menu, but the remote doesn't work (fresh batteries), and the button on the TV itself only accesses the quick menu, which only has volume, power, input, and channel options. I tried researching more, but it seems like everyone has video or power problem, which I do not, and their sound is fine. I was going to see if I could replace the main board, but can't find any in stock. I do see the eeprom available, but am not sure if that is the issue. I've also looked into voltage regulators, but am not sure if any are bad (I will list my results below). Does anyone have an idea of what else I can check? Or where I should go from here?

    Thanks,
    Brian

    Voltage Regulator Results (only ones i could find)

    1117 Type

    U2
    1 - 5.24v
    2 - 3.27v
    3 - 2.02v

    U4
    1 - 3.30v
    2 - 1.24v
    3 - 0.00v

    U46
    1 - 5.22v
    2 - 3.29v
    3 - 2.04v

    1084 type

    U3
    1 - 5.21v
    2 - 3.30v
    3 - 2.05v

    7805 Type

    U8

    1 - 5.03v
    2 - 0.00v
    3 - 12.01v

    #2
    Re: Vizio M420NV - No sound, remote not working

    I had the same issue a year ago the sound would not work. i plugged in a sound bar and had sound. after about 4 months the sound on the TV started working again. not sure why just did. but now the remote stopped working can it be the sensor?

    Comment


      #3
      Re: Vizio M420NV - No sound, remote not working

      check the +12v fuse going into the main board. post pictures of your main board

      Comment


        #4
        Re: Vizio M420NV - No sound, remote not working

        12V fuse on the main board is OK because the 7805 regulator U8 is getting the switched 12VDC from the power supply 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


          #5
          Re: Vizio M420NV - No sound, remote not working

          Anyone figure this out I am having the same problem remote wont work and no sound

          Comment


            #6
            Re: Vizio M420NV - No sound, remote not working

            Post some pictures of mainboard and connectors.
            I assume no responsibility for any stupid suggestions I might post.

            Comment


              #7
              Re: Vizio M420NV - No sound, remote not working

              Can you reset your set to Factory Default
              Willing to help but I'm no expert.

              Comment


                #8
                Re: Vizio M420NV - No sound, remote not working

                This problem sounds just like the Vizio SV470M. It is possible it could be a bad CPU. Here is the thread for the discussion about the SV470M

                https://www.badcaps.net/forum/showthread.php?t=38602

                Comment

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