Vizio VS420LF1A Screen/backlight goes off after awhile

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  • Blackwolf
    Member
    • Mar 2012
    • 18
    • USA
    #1

    Vizio VS420LF1A Screen/backlight goes off after awhile

    I have a Vizio VS420LF1A that i had previously posted about here in this forum.
    The back light and lcd was not coming on at all, yet the Vizio logo at the bottom was turning white. After testing several components i just gave up and purchased a new (used) PSU off ebay. I connected it and the TV worked great for 2 months or so. Unfortunately now Im having a problem where the tv will come on and work fine, but then the back light and lcd will just turn off (vizio logo still white) sometimes after several hours of use, or sometimes after just a few min. If i turn off the tv and let it sit for a few min after this happens, it will work for awhile, sometimes hours, sometimes just mins. Yesterday, the tv was on for several hours and worked perfectly, then towards the end of the night, it started doing it again. Im a bit puzzled as to why sometimes it works fine, then other times it exhibits this issue. I checked for obvious stuff like blown/bulging caps on the psu, but all looks well. I have pics that i took previously for the other thread available here
    Tags: None
    • tom66
      EVs Rule
      • Apr 2011
      • 32560
      • UK
      #2
      Re: Vizio VS420LF1A Screen/backlight goes off after awhile

      Try unplugging the button panel on the TV.
      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

        • Blackwolf
          Member
          • Mar 2012
          • 18
          • USA
          #3
          Re: Vizio VS420LF1A Screen/backlight goes off after awhile

          Ok i will try that, but would that cause the backlight/lcd to turn off but leaving the vizio logo white? (not orange like when its in standby)

            Comment

            • tom66
              EVs Rule
              • Apr 2011
              • 32560
              • UK
              #4
              Re: Vizio VS420LF1A Screen/backlight goes off after awhile

              Originally posted by Blackwolf
              Ok i will try that, but would that cause the backlight/lcd to turn off but leaving the vizio logo white? (not orange like when its in standby)
              Probably not - although maybe if the button gets stuck the TV does odd things like that?
              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

                • selldoor
                  Slow Learner
                  • Dec 2010
                  • 7870
                  #5
                  Re: Vizio VS420LF1A Screen/backlight goes off after awhile

                  Does the sound stay on? Have you checked to see if there is still a very dark picture on the screen when it appears to have gone off - try with a flashlight at different angles.
                  Please upload pictures using attachment function when ask for help on the repair
                  http://www.badcaps.net/forum/showthread.php?t=39740

                    Comment

                    • Blackwolf
                      Member
                      • Mar 2012
                      • 18
                      • USA
                      #6
                      Re: Vizio VS420LF1A Screen/backlight goes off after awhile

                      The sound does stay on, and i do see the picture on the LCD when i look closely at it with a flash light, so it must be the back light. I turned it on today and it stayed on for several hours with out going out but then it happened. Is it bad inverter or psu issue perhaps? Why does it sometimes work for hours then other times only a few min? Maybe theres a short or something?
                      Last edited by Blackwolf; 08-13-2012, 11:05 AM.

                        Comment

                        • selldoor
                          Slow Learner
                          • Dec 2010
                          • 7870
                          #7
                          Re: Vizio VS420LF1A Screen/backlight goes off after awhile

                          Please post clear pictures without flash of the inverter board and Tcon.
                          Please upload pictures using attachment function when ask for help on the repair
                          http://www.badcaps.net/forum/showthread.php?t=39740

                            Comment

                            • Blackwolf
                              Member
                              • Mar 2012
                              • 18
                              • USA
                              #8
                              Re: Vizio VS420LF1A Screen/backlight goes off after awhile

                              Some pics i took before are available here
                              https://www.badcaps.net/forum/showpo...33&postcount=3

                              These are the only 2 boards i see, is there another i may be missing somewhere?

                                Comment

                                • killian6pk
                                  Badcaps Veteran
                                  • Apr 2010
                                  • 502
                                  • USA
                                  #9
                                  Re: Vizio VS420LF1A Screen/backlight goes off after awhile

                                  There should be one and possibly two inverter boards probably under a metal cover one on each side of the tv. All of the backlight wires will be plugged into them.
                                  Have you ever stopped to think and then forget to start thinking again?

                                  As a very wise man once said on this forum: "Of all the things I have lost I miss my mind the most."

                                    Comment

                                    • killian6pk
                                      Badcaps Veteran
                                      • Apr 2010
                                      • 502
                                      • USA
                                      #10
                                      Re: Vizio VS420LF1A Screen/backlight goes off after awhile

                                      disregard my previous message looks like your backlights are run off the power board so you want have any inverter boards. Not sure how that is being done though with just two connectors.
                                      Last edited by killian6pk; 08-13-2012, 02:02 PM.
                                      Have you ever stopped to think and then forget to start thinking again?

                                      As a very wise man once said on this forum: "Of all the things I have lost I miss my mind the most."

                                        Comment

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