Question about Vizio VT420M LCD TV

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I was told by a service tech that my vizio tv model VT420M has a bad main board and that the board is not available. I have spoken with 2 more service companys and told the same thing. The set is 5 days out of factory warranty. I purchased it 12 months & 5 days ago. Any idea where I might find the board?

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Re: I was told by a service tech that my vizio tv model...

I just now called vizio and read your request word-for-word to their technical support person.
They have been known to fix these sets out of warranty. Although the girl said that she wasn't authorized to make that decision.
She told me to have you call this number 877-698-4946 Tomorrow when their level 3 technicians were available. She says that when you call the 1st tier tech support person will then send you one to these senior techs who can make the decision to cover it under warranty. My personal opinion is that they will take care of you. They say the "squeaky wheel gets the grease" I would go ahead and squeak. There is a link I've provided below to help.
I hope the helps,

Posted on Jan 19, 2011

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Hi I have a vizio vt42om the logo lights up then goes off is that the inverter board or the power supply or just the fuse

Sounds like main board fault. Short circuited component/s at it. Contact any service technician; or the authorized service center. If you wish to get some details; check the site linked here. Surf the site with patience. Pull up older posts. . In most cases, the main board might have to be replaced. If so, a software [firmware] update too might be necessary.

Dec 01, 2014 | Vizio VT420M LCD TV

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VT420M no sound or picture and turns off by itself

this sounds like a main board failure but a defective power supply can mimic some symptoms of a bad main board. I would recommend you get a diagnosis done on the set. If I was a betting man, I'd guess the main board

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Service manual

Send your email address to me by Fixya comment, and get a copy of the service manual by return mail.

Jul 13, 2012 | Vizio VT420M LCD TV

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Was told my backlight was out on my vt420m and it needed to be replaced

The backligts lamps rarely go out, but the backlights inverter boards that drive the lamps do go out often, you may need better tech that has real experience troubleshooting LCD TV.
Power supply, main board can also cause no lights on the screen. I would get second opinion.
Please read my guide to understand how LCD TV works.

Basic LCD monitor and TV troubleshooting guide:
Failed TV and Monitors pictures:
Learn about bad caps:

Capacitors kit: he can make you a set of caps.
Or, just make sure to use caps with low ESR, 105c, high ripple current and long life rating such as PANASONIC FM or FC series.
Please post back what you find.

Jun 29, 2011 | Vizio VT420M LCD TV

1 Answer

I've owned a Vizio VT420M for just over 13 months. About a week ago the tv started flickering when I turn it on. The picture is visable, but the area around the actors is flickering. After about 7 to 10...

The flickering is most likely due to a faulty fluorescent backlight. Once the bulb heats up the flickering usually goes away. Some bulbs are easier to replace than others so I would contact your local TV repair shop.

Mar 01, 2011 | Vizio VT420M LCD TV

1 Answer

My Vizio VT420M LCD TV has for several months has changed to a dark screen while viewing without any other problems. We always hit "power/cable" on the HD cable box and it would immediately come...

Now the tv u turn on u have a flashes of a picture only few sec. and died have sound left only?Yes,than the 2 long boards call the LCD inverter boards are the causes and the problems.These 2 long LCD inverter boards help the LCD screen panel to have a backlight to produced a picture.Tries websites like, to buy those 2 refurbishes long LCD inverter board for the replacement.

Jan 15, 2011 | Vizio VT420M LCD TV

2 Answers

There is no picture or sound. Had TV for 2 years. checked all connections. tried to re-boot through vizio tech support. had no luck.

You either have a power supply issue or a main board issue. It's best to take it to a service center to have it diagnosed properly.

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Vizio GLV47 LCD HD TV No Picture No Sound?!?!?!?!?

Without seeing the set and takig some measurements, I can't say for sure where the problem is, but the part info is listed below. These can be purchased through Please note that these boards have a "core" cost. This means that the "core" amount will be refunded to you once the defecive board is returned.


Power board: 0500-0510-0340 Cost: $102.97 Core: $10.00
Main board: 3647-0072-0150 Cost: $202.68 Core: $40.00

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