M471i-A2 No picture, no sound

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  • vbrad511
    Senior Member
    • Feb 2015
    • 70
    • United States

    #1

    M471i-A2 No picture, no sound

    I picked up this Vizio a month or so back from a gal who said it had been fine until the cable guy did something on/in her house. The backlights come on, but no visible picture, and no sound. First instinct told me main board. I've changed it, no difference. I got a good deal on a power board, still no difference. The screen lights up dark gray, and does change a bit with the buttons on the remote. I've been reading here on the site, and anywhere else I can for tips on this, but not finding much.
    Suggestions?
  • budm
    Badcaps Legend
    • Feb 2010
    • 40746
    • USA

    #2
    Re: M471i-A2 No picture, no sound

    Did you check for DCV between each end of the SMD fuse on the T-con board against the chassis GND to see what you get?
    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

    • vbrad511
      Senior Member
      • Feb 2015
      • 70
      • United States

      #3
      Re: M471i-A2 No picture, no sound

      T-con fuse is good. 12.1v both sides with set powered on.

      Comment

      • vbrad511
        Senior Member
        • Feb 2015
        • 70
        • United States

        #4
        Re: M471i-A2 No picture, no sound

        Just swapped in a new/good tcon. Same thing, no pic. Thinking I got a bad replacement main board.

        Comment

        • vbrad511
          Senior Member
          • Feb 2015
          • 70
          • United States

          #5
          Re: M471i-A2 No picture, no sound

          At the suggestion of an Ebayer I've dealt with I did some blind searching with the input button and do have sound, just no pic. The screen looks intact, but he says there's an ic on/in the panel that tends to go bad and isn't serviceable. Looks like maybe I'm out of luck on this one.

          Comment

          • vbrad511
            Senior Member
            • Feb 2015
            • 70
            • United States

            #6
            Re: M471i-A2 No picture, no sound

            Any last suggestions before I button this up and doom it to the recycler?

            Comment

            • vbrad511
              Senior Member
              • Feb 2015
              • 70
              • United States

              #7
              Re: M471i-A2 No picture, no sound

              Got it. Turns out whoever took the tv off the wall and attached the stand again used screws that were too long. I'd pretty much given up, but then remembered Aaron talking about the IC on the panel , so I thought I'd tear into it and see if I could even see what he was talking about. I didn't get that far into it. Where the cables come out of the tcon they run directly under metal strips along the bottom of the tv. One of the mount screws had been run into one of the strips and overtightened to the point of bending the metal to the point it made contact to some electronic gizmo (lack of technical term) on the circuit the tcon attaches to. Once I backed the metal strips loose, powered the tv up, randomly trying with one or both tcon cables off, I got differing screens. Ended up with two bad tcons (must've been shorted from the electrical contact). Tried one more that I had here, bent the metal strip back into shape, and everything's working fine.
              Just gotta remember to use correct length screws on these things.

              Comment

              • Electronic Handyman
                Senior Member
                • Apr 2016
                • 58
                • Canada

                #8
                Re: M471i-A2 No picture, no sound

                You're so right about using the proper length screws I've seen screws go right into the boards parts and short them out or they break something.This is not just true for TV's it's cars, toys and appliances etc I've seen many things over the years all caused by using either the wrong screws or wrong parts or by assembling something wrong etc.

                Atleast you found the problem congrats bud.

                Comment

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