Vizio 42" LCD TV Not Powering On

[vortalexfan]

Hello everyone yesterday I found a Vizio 42" LCD Smart TV in the trash and when I got it home and went to test it out, the TV is completely dead, it refuses to power on or anything.

I went to open it up to see if it might of been some bad capacitors in the power supply board, but none of the power supply caps seem to look bulgy or bad from what I can see.
But they really aren't all that easy to get to the way they designed this power supply board where there's aluminum heat sinks attached to MOSFET transistors that are also covering up access to all of the power supply capacitors.

I tested out the capacitors with my multimeter using the ohms setting and the capacitors seem to test fine, but then when I test them using the continuity tester mode of my multimeter they all fail miserably (they all check as open).

The model number of the TV by the way is SV422XVT and it doesn't look horribly old, and apparently alot of people on the internet seemed to of had issues with this TV either failing to power on a few months after buying it or it wanting to shut itself off after a while (both issues are signs of failed caps in the power supply in my experience with these TVs which is usually a cheap and easy fix).

Has anyone had any experience with these TVs?

Any help with this would be appreciated.

[freakaftr8]

Look on the standby pin from power supply going to mainboard. are you getting 5v stby?

If so, when you press power button, does 12v and or 24v come up or not?

Vizios have serious issues with 3 pin voltage regulators, 8 pin regulators, and eeprom issues.

Being this new, regulators usually are ok, but eeproms go bad. Look for 3.3v on eeprom pins.

All located on mainboard

[vortalexfan]

Originally Posted by freakaftr8

Look on the standby pin from power supply going to mainboard. are you getting 5v stby?

If so, when you press power button, does 12v and or 24v come up or not?

Vizios have serious issues with 3 pin voltage regulators, 8 pin regulators, and eeprom issues.

Being this new, regulators usually are ok, but eeproms go bad. Look for 3.3v on eeprom pins.

All located on mainboard

Ok, will check those areas out. Another issue i saw online was the control board going bad as well, but Im not sure if thats the issue with this particular tv or not.

[freakaftr8]

The mainboard is the control board.

[vortalexfan]

Originally Posted by freakaftr8

The mainboard is the control board.

Really? Then what the heck is this board pictured below?
Because when I looked up the control board on ebay, this board showed up in the results.

Even in some other electronics forums that I looked through that discussed this TV and this same exact symptom I'm having, mentioned something about a control board being the cause of the problem and that when they replaced that board the issue never happened again.

When I looked up the control board on ebay this board is what came up in the search results, the mainboard was a completely different assembly all together from the board pictured below.

I'm just curious as to what you think, because I've only done a hand full of sucessful Flat panel TV Resurrections mostly with bad capacitors in the power supply (older first generation flat panels, and one plasma tv that had a bad mainboard).

[freakaftr8]

That's the Tcon. Timing controller. sorry yes some people call that the control board. Not the culprit of your issues though. You could completely disconnect the LVDS cable from it and still get power up.

[freakaftr8]

Vizios rarely stem from capacitor failure. Especially everything built past 2006. The problem stems from the mainboard. Only if your standby 5v is there upend plugging it in.

[vortalexfan]

Originally Posted by freakaftr8

Vizios rarely stem from capacitor failure. Especially everything built past 2006. The problem stems from the mainboard. Only if your standby 5v is there upend plugging it in.

Ok, that answers my question.
Now my next question is, how the heck do I get a hold of a replacement mainboard for this TV?
I looked on eBay and all I found was someone offering a repair service for the original board that warranted their work for 1 year but they wanted 75 dollars for that, no functioning used boards for sale on eBay.
What part on the mainboard was usually at fault for causing this no power up issue?
Is it a part that one can easily replace and get at some place like digikey or Mouser?

[freakaftr8]

Probably of it's a flaky voltage regulator. but if it's an eeprom issue, I'd look at shopjimmy.. they usually carry all these high failure rate parts in stock. but since you cant find a mainboard, that's probably why. High failure item.

Take a pic of your board or post the mainboard part number.

Are you even getting an orange vizio light on the front?

Have a look at the 5v standby first, then we can go from there.