Vizio SV420XVT Distorted Picture Issue

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  • Timebomb606
    New Member
    • Aug 2013
    • 8
    • United States

    #1

    Vizio SV420XVT Distorted Picture Issue

    Hey guys,

    I got this TV from a friends parents who thought it was broken. When i got it home, i did a channel search and all was well. Well when i unhooked the coax from RF Input, the connector broke off and was on the end of the cable...no longer attached to the TV.

    So i got a new main board for this and installed it all. Exact same serial, and product code as the old one. Turn the TV on and nothing at all, no backlight, no sound, no vizio logo light up...nothing.

    So i have put the old board back in and im going to return the new one. Well now when i put the old one back in...its working fine, just the picture is all distorted as if something isnt connected right. All connections are fine as far as i can tell. There was a piece of "aluminum tape" id assume is what it is, prob for grounding purposes that isnt connected. It went from power supply board to chasis that covers the main board.

    Can that cause problems? No blown caps i can see, nothing else was touched at all.



    Any help would be appreciated.
  • Timebomb606
    New Member
    • Aug 2013
    • 8
    • United States

    #2
    Re: Vizio SV420XVT Distorted Picture Issue

    Anyone?

    Comment

    • Mrx3750
      Badcaps Veteran
      • Jul 2013
      • 311
      • USA

      #3
      Re: Vizio SV420XVT Distorted Picture Issue

      Either the new board is defective, or has the wrong software (programmed for a different LCD panel) Not sure what on your old board would cause a distorted image, except possible programming issues. Can you post a pic of the distorted image?
      Last edited by Mrx3750; 08-13-2013, 01:43 PM.

      Comment

      • aaronwt6
        Badcaps Veteran
        • Apr 2013
        • 855
        • US

        #4
        Re: Vizio SV420XVT Distorted Picture Issue

        Pictures of the boards and whatever the TV is doing would be very helpful in getting you an accurate response. My first hunch though on the original board is that it is in working condition and that you have a tab bond issue on the screen resulting in a distorted picture. If you are getting a motion blur effect with ghosting of images then that's most likely the culprit. You probably were just lucky the first time and the tabs had reconnected briefly from moving it around.

        Comment

        • aaronwt6
          Badcaps Veteran
          • Apr 2013
          • 855
          • US

          #5
          Re: Vizio SV420XVT Distorted Picture Issue

          You may have also just not reseated a cable well or have a tcon issue. Here's an example of one I got with a tab bond problem.

          https://www.badcaps.net/forum/showthread.php?t=28659

          Comment

          • Timebomb606
            New Member
            • Aug 2013
            • 8
            • United States

            #6
            Re: Vizio SV420XVT Distorted Picture Issue

            I have nothing like those pictures.

            Heres a few screenshots of the picture and the boards. There used to be a piece of tape from the yellow power supply to the cover over the main board. That wouldnt cause that image issue, right?

            Thanks again for your replies so far.
            Attached Files

            Comment

            • Mrx3750
              Badcaps Veteran
              • Jul 2013
              • 311
              • USA

              #7
              Re: Vizio SV420XVT Distorted Picture Issue

              That is a strange one. You seem to have the correct colors, just the image rendering is off. I'm wondering if electro static discharge might be to blame? Maybe when you removed the old board, you just set it aside, or maybe even threw it in the trash? Then when you realized the new board was faulty, you rescued the old board.

              I don't think missing grounding tape would cause such a weird issue.

              Comment

              • aaronwt6
                Badcaps Veteran
                • Apr 2013
                • 855
                • US

                #8
                Re: Vizio SV420XVT Distorted Picture Issue

                This is certainly something I haven't seen before. You'll have to wait for someone else to chime in on this.

                Comment

                • Timebomb606
                  New Member
                  • Aug 2013
                  • 8
                  • United States

                  #9
                  Re: Vizio SV420XVT Distorted Picture Issue

                  Alright, yeah when i removed the old board to install the new one. I just set the old one aside and then switched them back. Any idea if static discharge is an issue, is fixable?

                  Comment

                  • Mrx3750
                    Badcaps Veteran
                    • Jul 2013
                    • 311
                    • USA

                    #10
                    Re: Vizio SV420XVT Distorted Picture Issue

                    Electro static discharge can do all kinds of crazy things to motherboards, which is essentially what your chassis board is, a specialized motherboard. Things I've seen are a frozen BIOS clock, and yes, weird video errors. Not quite like yours, but you get the idea.

                    Now as to how fixable it is, easiest solution for you I think is to send your new board back for a replacement. I'd wait until someone more knowledgeable sees this thread, but it's likely not easily fixed.


                    Then again, if you could find the firmware and do a firmware update, who knows?
                    Last edited by Mrx3750; 08-13-2013, 03:41 PM.

                    Comment

                    • Timebomb606
                      New Member
                      • Aug 2013
                      • 8
                      • United States

                      #11
                      Re: Vizio SV420XVT Distorted Picture Issue

                      Its just so frustrating that it was working perfectly fine. Didnt change anything and now its not working.

                      Doesnt seem like it anything related to power, both boards i have power on. New board doesnt show a picture, only backlight comes on, nothing else. Cant use the power button to turn off either. Have to unplug it.

                      Old board allows TV to be turned on, shows that messed up picture though.

                      Comment

                      • Timebomb606
                        New Member
                        • Aug 2013
                        • 8
                        • United States

                        #12
                        Re: Vizio SV420XVT Distorted Picture Issue

                        So does anyone have a picture/diagram of what voltages the LDO's would have on this TV?

                        Comment

                        • Timebomb606
                          New Member
                          • Aug 2013
                          • 8
                          • United States

                          #13
                          Re: Vizio SV420XVT Distorted Picture Issue

                          Anyone have any other ideas what to check to diagnose this issue?

                          Comment

                          • tom66
                            EVs Rule
                            • Apr 2011
                            • 32560
                            • UK

                            #14
                            Re: Vizio SV420XVT Distorted Picture Issue

                            The voltages are written on the regulator for example LM1117-33 or LM1117-18 indicate 3.3V and 1.8V respectively. Or, if it is not labelled, the output is not directly known, but you can check the regulator function: the voltage between pins 1 and 2 should be approx 1.25V (+/-0.05V)
                            Last edited by tom66; 08-18-2013, 08:26 AM.
                            Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
                            For service manual, schematic, boardview (board view), datasheet, cad - use our search.

                            Comment

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