Vizio M420NV

Collapse
X
 
  • Time
  • Show
Clear All
new posts
  • nomursy
    New Member
    • Nov 2013
    • 8
    • us

    #1

    Vizio M420NV

    Hi and thanks for taking the time to offer your assistance. I have a 3 y/o Vizio M420NV that was working a few nights ago and then would not turn on in the morning. The orange Vizio light is on, but will not turn white when the power button is pushed on the side of the TV or with the remote. I tried the system reset (unplug for a while, hold power button on TV x 30 sec, plug in) with no change.

    I don't have any experience with circuit boards at the level I've been reading about on this forum, but I have picked up some basics from various posts and reading the stickies.

    After reading a lot of posts and talking to Vizio's out-of-warrenty repair company, I concluded (without any real evidence to back it up) that either the power board or main board was the culprit. I opted to buy a new power board to see if that would be the easy fix. I installed it tonight with no change in my situation.

    So, here's where I stand now….

    I have a new power board installed. With the TV plugged in, I read 12V on pins 8-10 (on the power board at the connection coming from the main board) and 3V on pin 11…all other pins had no readings. With the power button held down and then after it was released, there was no change in voltage at pin 11 (which I understand to be the point where the main board tells the TV to turn everything on…in very simplistic terms).

    I don't see any bulging caps on either board. I have an analogue multimeter and it's resistance selectors are either Rx10 or Rx1K. I tried testing the only thing I knew was a fuse on the power board (unplugged, selected Rx10) but saw no needle movement on either power board. I'm thinking, but not sure, that the 10x mag on the resistance is too much to be able to check the fuse.

    That's all the data I have. I'll try to attach pics of the boards. Thanks again for any input you have.





    Attached Files
  • budm
    Badcaps Legend
    • Feb 2010
    • 40746
    • USA

    #2
    Re: Vizio M420NV

    There are two fuses (F1, F2 next to the white connector to the left of the board) on the main board that you should check to see if it has dc voltage reading on both ends of the fuse with ref. to the chassis ground.
    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

    • nomursy
      New Member
      • Nov 2013
      • 8
      • us

      #3
      Re: Vizio M420NV

      I believe both fuses had DC voltage on both sides of the fuses. Just to make sure I did it right, here's what I did. Multimeter set to DCV 50. Neg to ground screw where the ground wire at the power plug in is attached. Red to each side of the fuse. The reading for the F2 fuse was twice as high as the F1 fuse (if I am reading the right line on the meter, the needle went to 55-60 on F2 and 25-30 on F1)
      Last edited by nomursy; 12-04-2013, 08:14 PM. Reason: messed up F1 and F2

      Comment

      • budm
        Badcaps Legend
        • Feb 2010
        • 40746
        • USA

        #4
        Re: Vizio M420NV

        I think you need to get Digital meter first, I am not sure what you are seeing on your meter. To it sounds like you have 5.5~6V on F2, and 2.5~3V on F1.
        I expect one of the them to be 5V (for logic circuit) and another one to be 12V (for sound amplifiers).
        Per picture, CN201 has pins for 5.3vstby and pins for 12V. Do get 5.3V at the CN201?
        Last edited by budm; 12-04-2013, 10:53 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

        • nomursy
          New Member
          • Nov 2013
          • 8
          • us

          #5
          Re: Vizio M420NV

          I think I was reading the wrong line of the meter and I did get 12 and about 5.3 at the fuses. I checked the pins on what I think is labeled CN202 (not 201?) and got 5.3 at pins 1-3 and 12 at 8-10. I'm trying to attach a pic of the meter reading one of the fuses.
          Attached Files

          Comment

          • nomursy
            New Member
            • Nov 2013
            • 8
            • us

            #6
            Re: Vizio M420NV

            Does anyone have any other ideas of what could be going on? Thanks again for all the help.

            Comment

            • Shane711
              Badcaps Veteran
              • Dec 2014
              • 493
              • USA

              #7
              Re: Vizio M420NV

              I have this problem with this TV. Same main board. The TV was working but was having trouble turning on after being off and the HDMI's were not working. I changed the EEPROM and now the TV will not turn on. I have not been able to figure out the problem.

              Comment

              • budm
                Badcaps Legend
                • Feb 2010
                • 40746
                • USA

                #8
                Re: Vizio M420NV

                Originally posted by Shane711
                I have this problem with this TV. Same main board. The TV was working but was having trouble turning on after being off and the HDMI's were not working. I changed the EEPROM and now the TV will not turn on. I have not been able to figure out the problem.
                So what happen if you put the old one back in?
                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

                • Shane711
                  Badcaps Veteran
                  • Dec 2014
                  • 493
                  • USA

                  #9
                  Re: Vizio M420NV

                  I put the old EEPROM back and the TV will not turn on. I am trying to figure out what happened, not sure if I caused something else to go bad. But since others are having the same problem maybe it is not my fault.

                  My friend has the same TV with a bad panel(Lines) so I plan to use it to fix the one I have. I will test both TVs to see if there is a difference in voltages between the 2.

                  Comment

                  Related Topics

                  Collapse

                  • m1ch43lzm
                    HP Pavilion 15-eh Board DAG7HAMB8F0 - CPU throttling to 0.4GHz (PROCHOT_EXT) and black screen
                    by m1ch43lzm
                    Hi, this is my personal laptop, which the original board (lets call it Board A) blew up PU8700 (TPS51486), making a hole on the board, i had left the laptop at my desk one day with the battery fully charged and didn't touch it for a week, but when i tried to turn it on it didn't
                    Thought the battery was dead, so i plugged in the charger then tried to power on, the power LED blinked once, charged LED still orange, unplugged the charger, plugged in again and I noticed the "magic smoke" smell, so i unplugged the charger, removed the back cover and saw the blown IC (the "magic...
                    05-12-2025, 08:37 PM
                  • Tynan Dill
                    Vizio e601i-A3 - Has Sound and Display, But No Backlight - Bad Power Supply Board or Bad LED Bulbs ?
                    by Tynan Dill
                    I was given this TV from my great uncle. He said it just wouldn't turn on one day out of nowhere, replaced the TV, and gave it to me to possibly fix and use for myself.

                    Upon bringing it home and plugging it up, it showed a standby light.

                    I powered it on and without a flashlight, the display showed the "V" but the lighting is very dim, but visible.

                    The screen seems to blackout and stay black, but with a flashlight I can see the display.

                    With my Playstation 4 connected via HDMI, and running a game I can hear sound.

                    Assuming...
                    11-22-2024, 01:46 PM
                  • howardc64
                    A1312 (27” iMac 2009-2011) A1407 (Thunderbolt Display) A1316 (Cinema Display) Display Black Screen Repair
                    by howardc64
                    Problem

                    This is an LG edge LED lit LCD Display. The LEDs are on the bottom edge of the display. There are 2 bars (left and right) Each bar has many LEDs and a 6 pin connector. Each pin drive several LEDs thus is the highest current flow / heat junction. The weak lead free solder gradually fails with thermal expansion/contraction cycling and increases resistance. PSU will compensate up to a point, then when the current is too high, PSU just shut down the backlight causing a dark display. I have even seen one which the connector just fell off as solder points became completely detached....
                    08-04-2024, 10:36 PM
                  • Hakuu
                    LG OLED77G1PUA - No Video / Audio after a TCON Board change and Software Update
                    by Hakuu
                    Hi There,

                    This TV was auto switching off after few seconds with some vertical lines on the screen, so got a new TCON board and replaced it.

                    After replacing the TCON board it was working fine and i set it up with everything, used for few hours, then had the bright idea to update the software on it. During the update process, TV switched off and now no audio or video. No relay switch sound.

                    More Details

                    TV Model - LG OLED77G1PUA

                    Got the same exact TCON board from TVPartsToday and replaced it. But didnt transfer the EPPROM data (didnt...
                    07-12-2023, 02:37 PM
                  • jb_Bak
                    Sony xbr-65x900c main board issues?
                    by jb_Bak
                    Hey guys great forum glad to have found it. I bought a Sony XBR 65X900C cheaply because it didn't work. No signs of life at all not even a light/led. All I hear is a brief high voltage sound when I throw the power to it.

                    Didn't see any obvious signs of damage so right away started checking voltages. This is what I see:
                    Power Board Connector that goes to Main board
                    CN6401
                    Pin 01 NC
                    Pin 02 NC
                    Pin 03 "BL_ON": 0V
                    Pin 04 "N/C"
                    Pin 05 "STBY 3.3V": 3.5V
                    Pin 06 "GND": N/C
                    Pin 07 "AC_OFF"...
                    09-27-2021, 04:52 PM
                  • Loading...
                  • No more items.
                  Working...