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TV Backlight Turns Off (Causes And How To Fix)

Few things are as frustrating as sitting down to relax in front of the TV at the end of a long day and being greeted by a black screen or having the backlight turn off at the most crucial moment in a show or movie. You know it’s the backlight because you can see faint lines on the screen if you hold a light over it. But what causes the backlight to turn off, and how can you fix it if it happens?

Your TV’s backlight can turn off randomly because of factors like fall damage, water damage, or faulty components. If your TV uses an old type of backlight, like incandescent bulbs, the bulbs may simply need replacing. LED backlights never burn out, but they can stop working for other reasons.

The TV as we know it today is a very mature technology, making it predictable. There are simple troubleshooting steps you can follow to find the problem. Not all troubleshooting and repairs are easy, though; some require a professional skillset to fix. But here are the most common causes of backlight problems and how you can fix those issues.

How To Know If Your TV’s Backlight Is The Problem

The first step in troubleshooting is to be sure that it is, in fact, the backlight and not some other problem. It’s easy to determine this. First, check that you have sound. If the TV’s sound works (not through external sound devices or speakers, but the TV’s built-in speakers), it’s not the full TV that’s dying. 

Secondly, switch on your TV as you normally would and start “watching” TV. None of the menus should pop up on the screen at all. But if you shine a strong flashlight directly into the TV, you should be able to see faint lines and movements, indicating that the TV is still drawing the image, but with no light behind it to light it up and make it visible.

If this is the case, your backlight is failing or has failed, and you can proceed with the other troubleshooting steps. If not, chances are that it’s another component entirely, and you should have a TV repair professional check it out.

TV Backlight Burn-Out

TV backlights come in two primary forms: LED backlights (which most modern TVs have) and a vague older variety that we will simply call “other.” Burnout will not be a problem if you have a modern LED TV. LEDs never heat up, so they can never burn out. Other things can make them fail, like power surges, but we will look at that more closely later.

The backlight likely consists of incandescent bulbs if you have an older flat-screen TV. These bulbs generate heat and can burn out with excessive use.

Though you can easily replace backlight bulbs if you’re handy with a screwdriver, it’s not as easy as all that, mainly because no TV manufacturer still uses incandescent bulbs, which makes them scarce and hard to find. If you can manage to find an older model that still has a working backlight, replacing it will be simple.

LED TV Backlight Failure

Modern TVs all use LEDs for the backlight. They don’t generate the same levels of heat as incandescent lamps. This also makes them last longer, use less electricity, and it also means you can have a much thinner TV screen due to their small size.

Even though it takes a lot for an LED to fail, it can happen. LED backlights can suffer the following damage:

  • Power surges can fry an LED. If the voltage and amps passing through an LED are too high, it will make a gentle pop and release a faint burning smell, then refuse to work again.
  • Water or other liquids can cause permanent damage to LEDs or entire LED strips.
  • If the TV falls or suffers other kinds of bumps, the LEDs can either come loose or suffer permanent damage.

The results could be the same, whether it’s just one LED that doesn’t work or an entire strip of LEDs. Many TVs have LEDs connected in a serial connection, which means that if one dies, the entire backlight stops working.

The excellent news is that replacing LED backlights in your TV is relatively easy. It requires a bit more knowledge of electronics, though, and apart from a screwdriver, you should also know how to use a soldering iron and a multimeter.

Replacing LEDs And LED Backlights

Use your multimeter to determine where the circuit of the backlight is broken. The multimeter will also help you to determine if it’s a single LED or an entire strip that needs to be replaced.

LEDs and LED strips are freely available at any electronics store. You don’t need to use the same brand as your TV; there’s a good chance your TV’s manufacturer used an off-brand LED type, too.

But before you buy, you should ensure you get suitable LEDs. You should pay close attention to the volts, amps, and ohms that your old LEDs were rated for and replace them with LEDs with identical ratings. Checking the physical size is also a good idea since LEDs come in different shapes and sizes, and you preferably want something similar in size.

Once you have the LEDs you need, it’s simply a process of using a soldering iron to (carefully) remove the faulty LED or LED strip and replace it with the new one you bought. If electronics isn’t one of your strong suits, get a professional to do this for you; it shouldn’t cost you very much.

Other Components That Could Cause TV Backlight Problems

Apart from the backlight itself, the power supply unit is the primary TV component that often causes a TV’s backlight to turn off. This unit takes the incoming voltage from the wall socket and converts it into the different voltages required to power the different parts of your TV, like the LCD screen and the backlight.

If there’s something wrong with your TV’s power supply, that obviously means that the TV will have all kinds of problems, including a backlight turning off. The two main things that can go wrong with the power supply in your TV are overheating and full-on failure.

If the power supply fails completely, you will probably have more than just a backlight failure. Your TV may turn off entirely after a few minutes, or it may not even come on at all. But suppose the failure is specifically related to the power supply’s ability to provide power to the backlight (usually the most power-hungry part of your TV). In that case, you will have to replace the power supply.

The more common problem is overheating. This often happens as the TV grows older or if the power supply suffers some damage due to a bump, a fall, or a liquid spill. Overheating causes a problem where your TV will work perfectly for a few minutes, and the backlight suddenly turns off. It will usually only come on again after you’ve left it switched off for a while.

You can test for overheating by pointing a cooling fan at your TV’s power supply (the area where the power cable connects to your TV). If it lasts longer or doesn’t switch off at all, it’s the power supply.

Since the power supply contains capacitors (powerful electronic components that can store high voltages), it’s not recommended that you try to fix it. The best idea is to remove the power supply and get a new one. It could be challenging to find a spare part, but for the most part, even similar parts (with the same ratings, inputs, and outputs) will do the trick.

Conclusion

TV backlights aren’t the most complicated parts of a TV to troubleshoot or replace, but that does not mean it’s easy. Whatever the cause of your backlight turning off, it’s always best to get a reliable, professional TV repair technician to fix it for you. They know the technical side better than most of us, so we should use their expertise.

References

https://www.ifixit.com/Wiki/iDevice_Backlight_Troubleshooting

https://blog.rentacenter.com/why-is-tv-screen-black/

https://lamphq.com/do-leds-burn-out/

https://www.gadgetreview.com/how-to-fix-backlight-on-tv