Vizio LED 42" E420VT ~ Smoking/Burnt Resistor - AVS Forum
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post #1 of 12 Old 12-21-2012, 11:04 PM - Thread Starter
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I REALLY NEED HELP! I have a Vizio 42" LED 1080p and have bought it a year ago. The other day it just started to smell like burning plastic and then all of sudden it pop'd and turned off. Doesn't turn on now.. so I unscrewed the back and I found a burn't capacitor which reads 102k/1kv . So i bought one and soldered it in still nothing (The Brown one). Maybe the fuse also blew? I would think so, also I'm sure something else caused the capacitor to burn up. There are no other sign of damage visibly, no bulged caps or leaking or anything like that.

Any and all help is appreciated.


Here is a pic of the board





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post #2 of 12 Old 12-22-2012, 06:37 AM
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Hi JD,

Those ceramic disk caps rarely go bad on their own. It is connected to a circuit that went bad and the result was the burning cap.

If I were to guess, I would say one or more of the diodes shorted out. I'm not sure if you have a meter and know how to use it because you questioned whether or not the fuse was bad instead of testing it to know for sure.

If you or a friend has a meter, put it on the ohms/diode setting and measure D601 and the diode below it, Maybe it is D601A.
Also measure the diode D603 and the transistors Q601 & Q601A under the big metal heat sink.
I suspect one of these has shorted and will read very low. A good diode will read .6v in one direction and open "OL" in the other when using the diode setting on the meter.

The coil LB602 right next to the burnt cap is suppose to read 0 ohms.

This is why I will spend the extra $40 for a 3 year extended warranty when I buy my next TV.

Good luck.
George
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post #3 of 12 Old 12-22-2012, 06:51 AM
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Quote:
Originally Posted by JDMovation View Post

I REALLY NEED HELP! I have a Vizio 42" LED 1080p and have bought it a year ago. The other day it just started to smell like burning plastic and then all of sudden it pop'd and turned off. Doesn't turn on now.. so I unscrewed the back and I found a burn't capacitor which reads 102k/1kv . So i bought one and soldered it in still nothing (The Brown one). Maybe the fuse also blew? I would think so, also I'm sure something else caused the capacitor to burn up. There are no other sign of damage visibly, no bulged caps or leaking or anything like that.
Any and all help is appreciated.
Here is a pic of the board



I wish you good luck with your issue by why is this posted in the Plasma forum ?

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post #4 of 12 Old 12-22-2012, 11:46 AM - Thread Starter
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Quote:
Originally Posted by georget View Post

Hi JD,
Those ceramic disk caps rarely go bad on their own. It is connected to a circuit that went bad and the result was the burning cap.
If I were to guess, I would say one or more of the diodes shorted out. I'm not sure if you have a meter and know how to use it because you questioned whether or not the fuse was bad instead of testing it to know for sure.
If you or a friend has a meter, put it on the ohms/diode setting and measure D601 and the diode below it, Maybe it is D601A.
Also measure the diode D603 and the transistors Q601 & Q601A under the big metal heat sink.
I suspect one of these has shorted and will read very low. A good diode will read .6v in one direction and open "OL" in the other when using the diode setting on the meter.
The coil LB602 right next to the burnt cap is suppose to read 0 ohms.
This is why I will spend the extra $40 for a 3 year extended warranty when I buy my next TV.
Good luck.
George

Thanks for the reply. I tested d601 and d601a and both have .6v but also getting the same reading both ways, is that normal? also LB602 is at 0 ohms.
Also how do I test the Q601 & Q601A? All I did was touch the terminal with the smaller ones one either side and got .3v on both q601 and q601a

Also the fuse only reads 110v on one side. The other is 0. So I presume it is blown?
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post #5 of 12 Old 12-22-2012, 12:18 PM
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Just as a sanity check, the 102k/1kv capacitor you replaced would be 1000pF (a.k.a. .001uF) and rated at 1,000 volts. Mention this because, given the abundance of solid state equipment that operates at low voltages, 1,000 volt replacement capacitors are more difficult to find today.

Given the voltage readings taken at the fuse terminals, it does appear to be blown. You can confirm with a multimeter (e.g. zero ohms).

You really can not test Q601 or Q601A , because you don't know what they are (e.g. Transistors, MOSFets, Regulators etc.) or type and/or functional pin-outs.

You would need a service manual (e.g. schematic diagrams, part numbers). Additionally, if needed, finding a suitable replacement part could be quite challenging/impossible.

Why not just buy a new power supply board, which seem to be available in the $30 - $50 range (e.g. retechtv, shopjimmy, ebay)?
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post #6 of 12 Old 12-23-2012, 07:03 AM
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Thiao is correct. Without a schematic, it can be difficult to tell if you are reading just the part or something in parallel. Some diodes normally read .3v in one direction if they are made of a certain material, and without taking the heat sink off and looking up the part to see what they are (transistor, SCR, etc...) it's tough to interpret the meter readings of Q601 or Q601A.

I was expecting to see a dead short on one of the parts. Perhaps it is no longer short but instead burnt open. Even if you discovered the bad part, and it is the only bad part on the board, sometimes it is a real pain to find a replacement part. I usually buy from Digikey. They have a huge selection and do not charge much for shipping.

You may be better off following Thiao's advice and search for the board on ShopJimmy. If they do not have it, they will keep you in their data base and send you notification when it comes in.

George
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post #7 of 12 Old 12-23-2012, 06:15 PM - Thread Starter
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Quote:
Originally Posted by thiao View Post

Just as a sanity check, the 102k/1kv capacitor you replaced would be 1000pF (a.k.a. .001uF) and rated at 1,000 volts. Mention this because, given the abundance of solid state equipment that operates at low voltages, 1,000 volt replacement capacitors are more difficult to find today.
Given the voltage readings taken at the fuse terminals, it does appear to be blown. You can confirm with a multimeter (e.g. zero ohms).
You really can not test Q601 or Q601A , because you don't know what they are (e.g. Transistors, MOSFets, Regulators etc.) or type and/or functional pin-outs.
You would need a service manual (e.g. schematic diagrams, part numbers). Additionally, if needed, finding a suitable replacement part could be quite challenging/impossible.
Why not just buy a new power supply board, which seem to be available in the $30 - $50 range (e.g. retechtv, shopjimmy, ebay)?

Ok I really was just hoping for it to be an easy fix. Don't we all! Well I purchased the disc from RadioShack.com. It is a 1000pf and it was only $1.09 for a 2pack. I will be looking for a new board then. maybe someone would like to buy mine for spare parts? I very much appreciate the help!
Quote:
Originally Posted by georget View Post

Thiao is correct. Without a schematic, it can be difficult to tell if you are reading just the part or something in parallel. Some diodes normally read .3v in one direction if they are made of a certain material, and without taking the heat sink off and looking up the part to see what they are (transistor, SCR, etc...) it's tough to interpret the meter readings of Q601 or Q601A.
I was expecting to see a dead short on one of the parts. Perhaps it is no longer short but instead burnt open. Even if you discovered the bad part, and it is the only bad part on the board, sometimes it is a real pain to find a replacement part. I usually buy from Digikey. They have a huge selection and do not charge much for shipping.
You may be better off following Thiao's advice and search for the board on ShopJimmy. If they do not have it, they will keep you in their data base and send you notification when it comes in.
George

Thankyou for your reply, Yes I had thought the same about it being burnt open I guess I'll never know. I will be looking for a new board.
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post #8 of 12 Old 12-23-2012, 06:58 PM - Thread Starter
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I put new fuse in and tv is working now.
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post #9 of 12 Old 12-24-2012, 06:06 AM
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Wow! That was a real Christmas present for the TV to work after replacing the fuse. I really thought something major shorted out that caused the cap to burn up and blow the fuse. Maybe it was just a defect part that broke down??? I know all parts are capable of going bad, but ceramic disc don't go bad very often.

Good job though, Hate to see a TV end up in a landfill because of 1 inexpensive bad part.

George
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post #10 of 12 Old 05-11-2013, 04:11 PM
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can you ttellme what you do because i have the same problem at the same tv
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post #11 of 12 Old 06-11-2013, 12:29 PM
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I have the exact same problem with my tv! The other day I heard a "pop", and I came back into the living room to discover that the tv would no longer power on. It is so crazy I found this thread, because the same exact part failed on my tv, and it appears to be the same mainboard! This must be a common problem with these Vizio models. So, all you had to do was replace the burnt part, and the fuse? I was just wondering if you could post which kind of fuse and resistor you bought, or a link to where I could purchase one would be fantastic!

Thanks! smile.gif
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post #12 of 12 Old 10-08-2013, 07:07 PM
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Greetings, good people of AVS Forum. I recently acquired a broken E420VT from a neighbor. Upon looking at the board, it seemed the capacitor in question had failed on mine also; there was a big black streak running all the way from the cap to a Schottky barrier rectifier under a small heatsink. I replaced both, as well as the fuse, and now the power LED glows blue, fading on and off, but the TV will not power on. I think my next step will be to replace the whole board, but I'm not sure if I should replace the power supply board or the main board. Any suggestions? My feeling is that since the power light is on, I should replace the main board in stead of the power board. Thanks in advance for any advice.


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