Why is my power board burning?

Question

Vizio E420-A0

Vizio 42" LED TV released in September 2012.

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Carey @tardisgrooves

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crwdns2893826:0crwdne2893826:0: Huk 26, 2018

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Why is my power board burning?

I’ve had my Vizio model M471i-a2 for about 4 years, and about a week ago it started emitting a strong burning smell, and then the top of the screen started having Black flickerings. Took off the back and saw a substantial burn mark on the power board.

Ordered a new board and put the new one in Saturday. Now (Monday night) the same thing is happening all over again to the brand new board!

Here’s a picture of the other side

Thank you turkey! Here’s a pic of the whole side of that board in case that’s helpful:

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Did you try connecting power through a different outlet?

crwdns2893770:0Huk 26, 2018crwdnd2893770:0 TechTalks crwdne2893770:0

Yes I did try another outlet

crwdns2893770:0Huk 27, 2018crwdnd2893770:0 Carey crwdne2893770:0

I have the same problem, did anyone find a solution for this?

crwdns2893770:0Maw 4, 2019crwdnd2893770:0 Dude Linger crwdne2893770:0

Hey dude, it did end up being my LED backlights. I wish I would have known that before purchasing new boards, as it will just burn through any new board you install.

crwdns2893770:0Maw 5, 2019crwdnd2893770:0 Carey crwdne2893770:0

I have this same issue on the same model tv. Same burn marks on same board. Do I need to replace the backlights and the board or just the backlights?

crwdns2893770:0Dzi 7, 2021crwdnd2893770:0 James Griffin crwdne2893770:0

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I have the same problem, did anyone find a solution for this? — Dude Linger
Hey dude, it did end up being my LED backlights. I wish I would have known that before purchasing new boards, as it will just burn through any new board you install. — Carey
I have this same issue on the same model tv. Same burn marks on same board. Do I need to replace the backlights and the board or just the backlights? — James Griffin

score 3 · Answer 1 · 2018-11-26T20:40:46-07:00

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oldturkey03 @oldturkey03

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crwdns2893826:0crwdne2893826:0: Huk 26, 2018

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@tardisgrooves

that is the cold side of the board and we really would need the underside of it as well. We would need to figure out what circuit those jumpers belong to. From their location I would think that this might be an issue related to the LED backlights. You can always try another board but do not connect the backlight connector and see if it does the same thing. without a schematic it could be difficult to check it any other way.

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New pic below

crwdns2893770:0Huk 27, 2018crwdnd2893770:0 Carey crwdne2893770:0

@tardisgrooves those look like MOSFETS Most likely for the LED boost circuit. I will try and see if I can find a schematic to verify this.

crwdns2893770:0Huk 27, 2018crwdnd2893770:0 oldturkey03 crwdne2893770:0

Thank you turkey! Bigger pic below

crwdns2893770:0Huk 28, 2018crwdnd2893770:0 Carey crwdne2893770:0

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