When your pet cat sheds your LCD TV suffers. Your screen isn't allergic to your cat -- that you know of -- but dust, hair and dander in the air can clog up the vents on electronics and cause overheating issues. Diagnosing the reason why a backlight turns off requires some sleuthing skills and a healthy dose of cleaning as well.
Sources of Overheating
The first, and easiest, thing to do is to dust the LCD screen. There are vents along the back and sides of the screen housing that are meant to allow air to flow through and cool down the internal components. Use a vacuum cleaner or canned air to remove the dust and pet hair that may have accumulated in the vents. If your LCD screen is especially dirty, you may need to remove the housing to get all of the gunk out.
If you decide to peek at the innards of your LCD screen, be sure that you've turned it off and unplugged it first. Be gentle as you work with the parts, especially with any plastic on the housing. Put a towel down on a smooth table and put the screen down on the towel so the back of the housing is facing up. Remove the screws and gently lift the housing off. Don't touch any of the components inside with your hands. Use canned air or a soft, lint-free cloth to clean away any dust or hair, especially from the vent areas. Clean the boards and circuits inside the housing as well as the housing that you lifted off.
Capacitors in Trouble
There are small, cylindrical components that exist inside most electronics called capacitors. Their job is to hold electrical energy until it's needed; they do so by putting two metal plates in an electrolytic solution. That matters to you because the solution can start to go bad and leak out of the capacitor, which would make the electrical energy in your LCD not flow correctly. Capacitors will have a cross scored into the metal on the top. If you see any black or brown in the cross, it indicates the capacitor is bulging and has gone bad. It will need to be replaced by desoldering the bad one and soldering a new one onto the board. If you're not handy with a soldering iron, it's best to let a professional handle such a repair.
Move the Air
If all the capacitors look fine and you've gotten rid of all the dust and hair and the LCD screen is still overheating, the problem might be caused by the inverter or the transformer. The backlight uses direct current electricity, so the alternating current that comes out of your outlet needs to be inverted and then transformed to the right voltage level. Both of those components may overheat and then switch off, which would cause the backlight to stop working.
Point a fan at the back of your LCD screen while it's running to see if the backlight stays on longer. If it does, then you know overheating is the issue. Inverters and transformers can sometimes be purchased aftermarket; if you're comfortable installing small components you can replace them yourself. You can narrow down which one is overheating by using a small fan and pointing it at just one component at a time until you find the one that needs to be cooled. The part number is often listed on the part itself.
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