Vizio M420NV - No sound, remote not working

[BriSpe]

My Vizio model m420nv TV recently had the sound go out. I tried to see if I could get sound out of the audio jack, but it didn't work. I switched from the DirectTV box to the DVD player to see if it was an input problem, but it didn't have sound either. After some research, some people reported the audio setting changes in the menu by itself. I tried to check the menu, but the remote doesn't work (fresh batteries), and the button on the TV itself only accesses the quick menu, which only has volume, power, input, and channel options. I tried researching more, but it seems like everyone has video or power problem, which I do not, and their sound is fine. I was going to see if I could replace the main board, but can't find any in stock. I do see the eeprom available, but am not sure if that is the issue. I've also looked into voltage regulators, but am not sure if any are bad (I will list my results below). Does anyone have an idea of what else I can check? Or where I should go from here?

Thanks,
Brian

Voltage Regulator Results (only ones i could find)

1117 Type

U2
1 - 5.24v
2 - 3.27v
3 - 2.02v

U4
1 - 3.30v
2 - 1.24v
3 - 0.00v

U46
1 - 5.22v
2 - 3.29v
3 - 2.04v

1084 type

U3
1 - 5.21v
2 - 3.30v
3 - 2.05v

7805 Type

U8
1 - 5.03v
2 - 0.00v
3 - 12.01v

[fl13lane@gmail.com]

Re: Vizio M420NV - No sound, remote not working

I had the same issue a year ago the sound would not work. i plugged in a sound bar and had sound. after about 4 months the sound on the TV started working again. not sure why just did. but now the remote stopped working can it be the sensor?

[ecking767]

Re: Vizio M420NV - No sound, remote not working

check the +12v fuse going into the main board. post pictures of your main board

[budm]

Re: Vizio M420NV - No sound, remote not working

12V fuse on the main board is OK because the 7805 regulator U8 is getting the switched 12VDC from the power supply OK.

[Sauktronics]

Re: Vizio M420NV - No sound, remote not working

Anyone figure this out I am having the same problem remote wont work and no sound

[dskall]

Re: Vizio M420NV - No sound, remote not working

Post some pictures of mainboard and connectors.

[dick_barton]

Re: Vizio M420NV - No sound, remote not working

Can you reset your set to Factory Default

[Shane711]

Re: Vizio M420NV - No sound, remote not working

This problem sounds just like the Vizio SV470M. It is possible it could be a bad CPU. Here is the thread for the discussion about the SV470M

https://www.badcaps.net/forum/showthread.php?t=38602