The TV is turned on and has only sound with backlight.The problem is it takes several times turn on and off to make the picture come up. When it came up picture has a lot of horizon lines like static

Sounds like the LED backlighting has failed. There are a string of tiny LED's that make up the backlight on an LCD TV and it only takes one of them (depending on what brand TV) to fail for the whole backlight circuit to go out.

https://forums.whirlpool.net.au/archive/2720191

The Audio and Video are two separate components and operate independently of each other. Therefore: The Video portion requires technical repair by a technician with the proper test equipment.

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ok I have ran across this before.. First turn on the TV and go to a channel u know is good, with sound.. now turn off lights in the room.. or just darken the room.. next take a FLASHLIGHT and turn it on and shine it into the front of TV . If u see the images on the screen when moving the flashlight around. that is a good sign.. That usually means the Backlight board or boards are not working..with the TV on and in a darken room you should be able to see light coming through some of the Vent holes in the back cover, that means the Backlight board is working. from what u say I would bet on the backlight boards. pretty easy fix.. Unplug from the AC outlet. remove the back. Now be careful back there cause u can still get Zapped. I ALWAYS take pictures of the back (close up of the model and serial #'s) I take several pictures of the inside of the TV. some TV's have the Backlight board or boards on the side of the screen and some have the backlight inverter built in the main board, since u have already replace the main board u must have backlights separated. . Take close up shots of the board, and write down all the #'s from the board and when u order make sure u order the exact one..I never remove the bad board till I have the new one ready to install. I always go to ShopJimmy.com first to see if they have the part. Then I check Amazon, and then eBay. in that order.try to buy NEW boards if u can.. Hope this helps.

oh, so that's your problem. I'm willing to bet you have a picture but just no backlight. Now does the screen come on briefly when you first turn the TV on? Or is the screen black at all times?? Turn on the TV, turn off the lights in the room. Take a very bright flash light and shine it one the screen.I bet you see a dim picture. It sounds like you have a backlight problem. Either you are missing 24VDC from the power supply, 3.3VDC "backlight on" signal from the main board, a bad inverter, or a bad backlamp.

Might be a bad CCFL backlight lamp in the LCD panel. Take the LCD panel apart and turn power on to see the lamp that is out. If one is bad just replace it and the tv should have picture on it

This tv seem to have two problems.The problems that the tv take a long time the tv to turn on,the tv power supply board have dying capacitors most likely.That the board where the power a/c cord plug into it.The picture flickers badly this problems is harder to determine because this causes by two backlight buffers boards X,Z buffers boards could be either one it is dying.This tv should get an estamate by a shop or shops and repair it by them,bcause the tv must have to be doing replacing x munbers capacitors components to the tv power supply board and alot more work to trouble shoot and to detrmine which of the buffers boards it is the causes of to the picture screen to be badly flickers and replacing it.

Take it back and see if another does the same thing before you get out of the store. There's something loose in the backlight circuit, like a power inductor. They shouldn't do that.

Tell Vizio send out the tech.to replace ur Backlight video inverter board,it dying go to be dead sooner or later.Or take the refurbished tv ur tv will have dead video soon.

sounds like you have a bad panel. This ussually happens when a backlight lamp has gone bad and the inverter board senses this and sends a signal to turn the backlight off.