Vizio 55 inch led sound but no picture

It sounds like you may have a problem with the video signal on your Vizio 55 inch flat screen TV. The fact that the TV turns on and has sound, but no video and vertical lines on the screen, suggests that there may be an issue with the video processing or display.
It could be a problem with the T-CON board, which is responsible for the video signal processing. It could also be a problem with the LCD panel itself.
It's also possible that there's an issue with the cable connecting the T-CON board to the LCD panel, or a problem with the software on the main board.
I recommend consulting the manual of the TV or contacting the manufacturer for further assistance. A professional technician should be able to diagnose and fix the problem.
It's also possible that the issue is with the mainboard or the T-CON board is not compatible with the TV. Thus, it's best to check the compatibility of the parts with the TV before installing it.

What's the model of your TV Duane? WIthout that it's hard to offer much help

Isn't it ovbious...no backlight = bad lamps, of 100 sets I work on with no picture but sound 95 of them turn out to be bad backlights, it's unfortunate you waisted money on a power board as it could have been tested verses replace it

Hello Brian, if you have changed the power supply board and still have no image, then some of the LEDs that are responsible for illuminating the screen are wrong, to solve the problem, you should replace all the LED strips, because if only change the ones that have one or two damaged Leds, the other strips, they could fail you soon and you would have the same problem again
I sent you a video of [ShopJimmy.com] that shows you how to replace the LED strips, in another Vizio TV model of 55 "
I hope you can solve the problem of your TV Vizio
Greetings Franco Dosil

Hola Brian, si has cambiado la placa de la fuente de alimentaci?n y todav?a no tienes imagen, entonces est?n mal algunos de los Leds que se encargan de iluminar la pantalla, para resolver el problema, deber?as reemplazar todas las tiras de Leds, porque si solo cambias las que tengan uno o dos Leds da?ados, las otras tiras, podr?an fallarte pronto y volver?as a tener el mismo problema
Te env?o un v?deo de [ShopJimmy.com] que te muestra como reemplazar las tiras de Leds, en otro modelo de TV Vizio de 55"
Espero puedas resolver el problema de tu TV Vizio
Saludos Franco Dosil

Main board is most likely the problem

Sounds like back - light problem. Check and replace damaged component/s at its back-light inverter board, or replace this board as card basis. If you wish to get some details; check the site linked here. Surf the site with patience. Pull up older posts. It will be best to replace the inverter board as card basis.
http://electro-medical.blogspot.com/
To some model sets; especially LED back-lighted types; the back-light inverter circuit will be part of the main power supply board [SMPS]. In such cases, the power supply board might need replacement. To some models sets, the back-light inverter and SMPS section circuit will be integrated at its main board itself. If so; the main board should be replaced. To some models of sets, all these section circuit will be integrated at its main board. If this is the case, you have to replace the main board.

Vizio 0500-0612-0030 Power Supply / LED Board for M550NV

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Vizio 55" M550NV 0500-0612-0030 LCD Power Supply Board Unit Motherboard. ... Any tears or bad connections between boards must be replaced FIRST. 2.

EASY HOW TO FIX LED Vizio TV- no power - YouTube

? 6:13
https://www.youtube.com/watch?v=9xZcTWr2yV0
Nov 5, 2013 - Uploaded by Tampatec
DiY How to Fix led / lcd Vizio TV service repair - no power service repair ... I can not get it to power on so I ...

carefully remove the back panel with the set face down and remove the ribbon cable running to the t-con board and replace it

Try this thread : SOLVED VIZIO M550NV NO PICTURE NO SOUND It sounds like the same problem that you have.

I have been having the same problem with my LG. people say there are bad capacitors on the power supply board. I don't have the know how to replace them and don't have the money to pay. I can get mine to work by blowing hot air with a hair dryer into the back of my tv through the vents over the board. Heat it up for a couple minutes and turn it off and then back on and the picture comes back. I just never turn the set off now.