What Could Cause a TV Screen to Start Flickering Like a Strobe Light?

By Elizabeth Falwell

No, you haven't stumbled in to a rock concert or a Halloween fun house - but if your TV screen flickers, you may feel as if you have. Everything from a faulty power source to a poor refresh rate to a dying backlight can cause your TV to flash and flicker. The source of the problem is largely linked to what type of technology your TV uses.

Refresh Rate

Your television's refresh rate refers to the frequency at which your TV receives new data from the source -- such as your cable box or DVD player -- and refreshes the information on your screen. Most TV studios broadcast at a speed of 60Hz, or 60 frames per second, while film -- especially older movies -- is generally slower at 24 frames per second. Your liquid crystal display, or LCD, and cathode-ray tube, or CRT, TV has a refresh rate too, usually starting at 60Hz for most CRT and older LCD models. Plasma TVs don't have refresh rates, despite what some advertisers may claim, because they are constantly scanning for new data. When your TV can't keep up with the speed at which it's receiving information from the source, the screen may flicker, pixelate or even start to freeze frame.

Power Source

All TVs -- whether LCD, plasma or CRT -- are vulnerable to flickering caused by a faulty power source. Your TV needs a constant, steady flow of power in order to produce the pictures you see on your screen. If the power cord isn't plugged in completely to an electrical socket, or if the cord itself is damaged in any way, it can prevent your TV from getting the electricity it needs to broadcast a smooth picture.

Failing Backlight

The problem of a failing backlight is unique to LCD TVs. Unlike CRT and plasma televisions, the liquid crystals that generate the images you see on your screen are unable to illuminate themselves. Instead, they require a third party backlight. Light-emitting diodes, or LEDs, and cold-cathode fluorescent lamps, or CCFLs, are the two types of backlights used in LCD TVs. When these backlights start to fail -- around 50,000 viewing hours for the more energy-efficient LED lights and between 20,000 and 40,000 viewing hours for CCFLs -- one of the first symptoms is an obvious flicker onscreen. Changing your TV's backlight alleviates this issue.

Signal Interruptions

Whether you have a CRT, LCD or plasma TV, the pictures on your screen are only as good as the signal it receives. If you subscribe to cable or satellite service, check the coaxial cables connecting your home's exterior cable box or satellite dish to your TV's set-top receiver and to the TV itself. Any interruptions or damage along these cables degrade the signal, causing video interruptions such as flickering, pixelation and freeze framing. If problems persist, reset your set-top receiver by unplugging it from its power source for up to 30 seconds in order to force the box to automatically scan for updates from your cable or satellite provider which could reduce the video problems.