Repairing LCD TV - Westinghouse LTV-32W3

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I am trying repaire my LCD TV Westinghouse LTV-32W3. I purchased it 1 1/2 year ago - it worked OK for about 1 year. After warranty expired it works OK for about hour, after 1 hour the following symptoms appeared: http://www.evkosystems.kgbinternet.com/evkosystems/tv/Bad-TV-2-1.wmv The TV on the left is a good one, on the right Westinghouse LTV-32W3
I come to conclusion that some parts in the TV are getting too hot. To test my theory I removed TV's back cover to allow better air circulation - now TV is working without problem. What I want to do is to install small fan to make a better cooling. I am not a TV technician, so here are my questions:
electronics parts that are getting hot are enclosed in a metal case:
http://www.evkosystems.kgbinternet.com/evkosystems/tv/IMG_0014.JPG
here electonic parts with metal case removed:
http://www.evkosystems.kgbinternet.com/evkosystems/tv/IMG_0017.JPG
I guess the metal case is to prevent electromagnetic transmition - can I make more holes in a metal case without causing electromagnetic interferrence?
I plan to put inside a small fan, similar to one used in computers - can you recommend one? Can you recommend simply converter from 110 AC to 5V(?) DC to power this fan?
Thanks,
Zalek
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You can purchase a 120V AC fan at an electrical store, but make sure it not too fast or you will hear it. Most computer fans are 12V and will work with just about any 12V converter that you laying around, or you can get one at an electronics stores.
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If it was me, I'd put a small fan in the lower right (viewed from the back) section pointing towards the side (just below where the power cable connects) to suck air from the inside. You can get those same style fans in 115 VAC (GOOGLE is your friend) so as not to have to deal with another power supply. BTW, computer fans are usually 12 V not 5 V.
--
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snipped-for-privacy@nowhere.non says...

And should you put a fan in be sure to use a filter. Dust is another enemy of small electronics.
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In article <30022c55-c5f2-4bba-b09b-f09a6fc797a7

It should be on the intake of the fan. As for AC/DC I dont' honesly know, but I recall that most I've run across seem to be DC.
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If it was me, I think I would try to figure out what is actually wrong with it first. Fitting a fan is attacking the symptoms rather than the cause, and if a component such as an electrolytic cap is failing, or a bad joint is starting to show up, it is unlikely that its demise will be arrested for good, merely by the addition of a fan. It's a bit like going to the doctor and telling him that you get short of breath when you climb the stairs, and his 'fix' for your problem being to suggest installing a stairlift ...
An intermittent problem such as is shown in your film, and that is clearly heat related, should not be difficult to find, if you approach it armed with a hair dryer, and a can of freezer. If it then proved to be an 'unrepairable' fault such as one of the LSIs, or even just a bad joint on one, that you likely wouldn't be able to fix with basic home soldering equipment, then you might consider that your TV has terminal lung cancer, and the best you can do is to get what remaining life out of it that you can, by installing that 'stairlift' !
Arfa
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On Mon, 04 Feb 2008 01:14:16 +0000, Arfa Daily wrote:

It's like putting a BandAid on a skin Melanoma.
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On Sun, 03 Feb 2008 18:11:23 GMT, snipped-for-privacy@hotmail.com wrote:

Is the case itself getting hot? If so, simply sticking on some passive heat sinks might do the job, something like:
http://rocky.digikey.com/scripts/ProductInfo.dll?Site=US&VY&M 8540B00000
J.
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On Sun, 03 Feb 2008 18:11:23 GMT, snipped-for-privacy@hotmail.com wrote:

A fan will only solve the problem temporarily.
Why? Because the TV worked okay for over a year before developing this symtom. That means something has changed or deteriorated. You have what is called a "thermal intermittant". That's a problem that shows itself when things get either hot or cold. The problem is either a solder connection that is going bad or a component that is failing. If it is a component that is failing, it may be stressing other components at the same time.
You are ultimately not going to win this one. That much is certain. If the TV isn't worth a trip to the shop for a proper diagnosis and repair, then you have nothing to lose except the time and effort. Even with your makeshift work-around, it's days are numbered. The problem will get worse until there is a more profound failure.
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Most competent technicians would have had a heat gun and a spot heater and known how to use them to induce thermal problems to make them present themselves.
Very basic technique in TV repair.
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snipped-for-privacy@hotmail.com writes:

Those bands are the most common failure mode for LCDs. There is some kind connector inside with a lot of pins. The heat is making them loose contact.
I don't think it's cost effective to repair, but if you succeed let us know. I have 2 LCDs with this problem that I'm going to dispose of in the spring cleanup.
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snipped-for-privacy@hotmail.com wrote:

Frys and other electronics shops have cans of "circuit cooler" that can be used to chill a suspect part. You might be able to pinpoint the part that has changed value over time. I would tend to look at electrolytic capacitors first, then stressed diodes or transistors.
Also, try repair shops that have worked on that model, most likely it is developing a reputation that a tech has seen before. try the electronics repair boards, or google that model and "+trouble".
-- larry / dallas
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I would try to troubleshoot the set to find the components that have become thermo sensitive, and change them. Then I would put in a fan if I thought the set was running too hot.
If you have some thermo sensitive components in the TV set, with time they will keep degrading until they fail. At this point, the problem may be more serious.
--

Jerry G.


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In article <9413130f-117e-4d46-aac7-1b5f6b7ba565

It's an LCD, which means it's more than likely a low voltage device. Doesn't take much more than 12V tops to run them.
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And 800V (or so) running the lamps so that you can see the picture on the 12V screen...before you go getting all comfortable poking around in there.
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snipped-for-privacy@SOuthernVERmont.NyET says...

Is it really 800V? If so what does my laptop use to step the voltage up to that level?
There are low voltage fluorescents out there. I know, I have one in my toolkit and it runs on 4.5V.
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wrote:

Fluorescents are discharge lamps, the smallest in the world require somewhere around 50V to draw an arc through the low pressure argon/mercury fill. Cold cathode lamps used in LCD monitors require a higher voltage, usually 500-1500V run with a 2-4KV ignition pulse. Any fluorescent application with a low voltage power source uses an electronic inverter to provide the required voltage and regulate lamp power.
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Voltage converters.

It uses 4.5 volts input to the voltage converter. A fluorescent requires enough voltage to create an arc in the mercury vapor.
    Alan
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snipped-for-privacy@hotmail.com wrote:
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On Sun, 03 Feb 2008 18:11:23 GMT, snipped-for-privacy@hotmail.com put finger to keyboard and composed:

I have no experience with LCD TVS (only LCD monitors), but I'm wondering what is inside the tuner/IF can that warrants a heatsink for this module? And why do the other chips require such massive heatsinks when I see nothing of that kind in LCD monitors or digital STBs?
- Franc Zabkar
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