What Causes Flashing Backlights With an LCD?

by Elizabeth Falwell
LCD TVs rely on backlights to illuminate the picture on the screen.

LCD TVs rely on backlights to illuminate the picture on the screen.

It doesn't matter whether your LCD TV uses a CCFL or an LED backlight -- if the screen starts flashing, flickering or dimming, it usually means one of three things: the bulb is dying, the inverter is broken or the bulb was incorrectly installed. Fortunately, a TV repair service can easily fix all these problems.

How LCD TVs Work

Unlike plasma televisions, in which the plasma molecules can illuminate themselves, the liquid crystals in LCD TVs are transmissive. This means they require a third party to light up the image on the screen. LCDs use two main types of backlighting technology. The first and older of the two is CCFL, short for "cold-cathode fluorescent lamp." The more modern of the two is LED, which stands for "light-emitting diodes."

Dying Backlights

LCD TVs have a lifespan of between 60,000 and 100,000 viewing hours. On the high end, this means you could keep your LCD TV on 24/7 for more than 11 years. However, neither LED nor CCFL bulbs have such a long lifespan. The website "Electronics Weekly" says the average LED backlight lasts about 50,000 viewing hours, while a CCFL backlight usually lasts between 20,000 and 40,000 viewing hours. If the image on your screen flickers or flashes, it may be a sign that the backlight is dying and needs to be replaced.

Dying Inverter

According to one CCFL bulb online retailer, dying backlights are responsible for roughly 95 percent of flickering and flashing backlights. However, in the other five percent of cases, a problematic inverter may be to blame. The inverter supplies the backlight with its power. When the inverter begins to fail, it disrupts this flow of electricity, resulting in a flashing or flickering bulb. Just as the backlight itself can be replaced to elongate the lifespan of an LCD TV, so can the inverter.

Improperly Installed Equipment

Installing a new backlight -- whether using CCFL or LED bulbs -- is not a task for a novice. It involves detaching the LCD screen from the rest of the television, removing the old light and soldering the new one into place. Improperly installing either the backlight or the inverter will result in a bulb that is not receiving the full flow of electricity. Just as a regular light bulb in a lamp will flicker when it's not screwed in all the way, so will a CCFL or LED backlight when it is incorrectly installed. For this reason, you should have a professional install these critical elements for you.

About the Author

Elizabeth Falwell has been writing for the TV news industry since 2005. Her work has appeared on WXII 12 News, WMGT 41 News, NewParent.com and multiple parenting blogs. A graduate of the S.I. Newhouse School at Syracuse University, Falwell holds a Master of Science in broadcast journalism.

Photo Credits

  • photo_camera flashfilm/Lifesize/Getty Images