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Vizio LED 42" E420VT ~ Smoking/Burnt Resistor

post #1 of 10
12/21/12 at 10:04pm
Thread Starter 
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 10
12/22/12 at 5:37am
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 10
12/22/12 at 5:51am
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 10
12/22/12 at 10:46am
Thread Starter 
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?
Edited by JDMovation - 12/22/12 at 11:32am
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post #5 of 10
12/22/12 at 11:18am
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)?
Edited by thiao - 12/22/12 at 11:28am
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post #6 of 10
12/23/12 at 6:03am
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 10
12/23/12 at 5:15pm
Thread Starter 
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 10
12/23/12 at 5:58pm
Thread Starter 
I put new fuse in and tv is working now.
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post #9 of 10
12/24/12 at 5:06am
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 10
5/11/13 at 3:11pm
can you ttellme what you do because i have the same problem at the same tv
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