Vizio M420NV Powers on for a few seconds then resets

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  • kisk
    Computer Tech
    • Jan 2014
    • 78
    • USA
    #1

    Vizio M420NV Powers on for a few seconds then resets

    I have a friend who's Vizio is having issues. I have the set here and have recapped the entire power board but still having the same issues.

    From a cold start (>10m) the unit will stay powered on for about 2 minutes. After that time, it reboots. Each time it reboots the time till failure decreases. After about 5 reboots it only stays on for maybe 10 seconds then continues to reboot. If you leave the unit unplugged for about 10-15 minutes it will stay on for another 2 minutes or so before doing this all over.

    He had actually called Vizio and they were going to send someone out and "replace the power board" for $199. Hardly worth it since I was almost sure it was a cap issue because of the symptoms, however it wasn't.

    Anybody up for helping me diagnose this sucker? Looks like a combination power/inverter board and I suspect something is heating up and then failing -- I'm just not sure where to start and I can't find a schematic for this thing. It doesn't seem like the normal eeprom issue you normally see with the Vizios.

    I have my dmm ready! Thanks!


    EDIT: I did not replace the 2 big 450v caps. I believe these are know as the filter caps?
    Last edited by kisk; 01-13-2015, 09:37 PM.
    Tags: None
    • kisk
      Computer Tech
      • Jan 2014
      • 78
      • USA
      #2
      Re: Vizio M420NV Powers on for a few seconds then resets

      oops, pics:

      And if I need to take additional pics let me know!
      Attached Files

        Comment

        • kisk
          Computer Tech
          • Jan 2014
          • 78
          • USA
          #3
          Re: Vizio M420NV Powers on for a few seconds then resets

          Well ended up ordering a new power board for this thing and its doing the same thing.

          I know vizios are known for bad eeproms. Would what is happening here be in the same realm as a bad firmware chip.

          Whatever it is, it seems like something is warming up, expanding, then faulting. Not sure where to go from here other than blindly order a new eeprom or mainboard. Any ideas?

          EDIT: BTW, I was going to try and flash a newer firmware to see if that fixed it but I can't find any types of downloads on the Vizio site whatsoever.
          Last edited by kisk; 01-22-2015, 11:45 AM.

            Comment

            • budm
              Badcaps Legend
              • Feb 2010
              • 40746
              • USA
              #4
              Re: Vizio M420NV Powers on for a few seconds then resets

              Shopjimmy sells EEPROM so I will not be surprised if you have EEPROM problem.
              http://www.shopjimmy.com/catalogsear...q=Vizio+M420NV
              And also these two ICs that you should look and see what they are:
              http://www.shopjimmy.com/vizio-3642-...for-m420nv.htm

              You may want to contact SJ to see what they will say about your symptom, they are really helpful on pointing out the cause of the problems.
              Last edited by budm; 01-22-2015, 12:14 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

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