Attempting to settle in and enjoy that latest movie or TV show and having that relaxation interfered with by a flickering screen can be annoying. Televisions that exhibit flicker can do so for a variety of reasons, some internal and others external. In most cases, the user can reduce or eliminate the phenomenon with basic troubleshooting techniques.
Loose or defective cables leading into the set can result in screen flicker. In the case of High Definition Multimedia Interface, or HDMI cables, the result is "snow" or flickering colors. With coaxial and other analog cable types, the result is typically random and abrupt variations in brightness and color intensity. Replacing the cable and/or checking the tightness to the set by applying a slight wiggle while pushing in gently normally resolves the issue.
Other appliances in the home can draw enough power to cause flickering if they are on the the same circuit. This is most noticeable as abrupt dimming of the image as the appliance turns on; after the appliance's power cycle is complete normal brightness is restored. This is resolved by having an electrician check the primary ground at the service panel, ensuring a tight connection. In more extreme cases, a dedicated outlet is run to service either the appliance or the television and related audio/visual gear.
In cathode ray tube, or CRT sets, accumulated dust and hair results in electrical arcing. This normally presents itself in large-chassis rear projection sets, whose large current draw is a dust magnet. This arcing looks like a brief "squiggle" or jumping of the image, occurring randomly. Cleaning out the set in this case is good maintenance and a probable fix for the issue. Additionally, maintaining a normal level of household humidity at or above 70 percent reduces arcing.
Dying Power Supply
Power supply circuitry in a television maintains the proper level of voltage required to keep a picture at a stable level of brightness. As these power supplies begin to fail, you will notice a marked dimming and abrupt brightness level change. At some point, the set will fade to black. A qualified service tech is needed or, in the case of CRT televisions for which parts are often scarce, replacement.