Static interference or other forms of distortion in a cable TV signal can originate in any of several possible sources. They include faulty cables, weak signal, interference from other electrical devices and problems with the cable provider itself. You can investigate and fix most problems at home through a process of elimination.
Check other channels for static. If you only have static on one or two channels, there might be a problem with the incoming signal from the cable company. If you have other TVs in the house, also check them for static. If all of your televisions are getting the same static-filled picture, then the incoming cable signal is likely the source of the issue. Call your cable provider and ask if it has problems with certain channels.
Turn off other electronic devices. If your house has older wiring, other electrical devices may send interference to your TV set and cable box. High-amperage devices like vacuums and blenders are the most likely culprits. Any device with speakers and any device transmitting a wireless signal should also be investigated.
Check all connections -- the back of the TV, the wall jack or any connected cable boxes, DVRs, DVDs, Blu-ray players and home theater systems. If any connection feels loose or jiggly, tighten the cable. Quality coaxial cables have a threaded connector that you can tighten with a pair of pliers. If any of your cables have low-quality "push on" cable connectors -- the kind often packaged with external AV equipment -- consider swapping them for heavy-duty cables with threaded connectors.
Move the coaxial cables away from other cables. Your TV cables may be receiving electromagnetic interference from nearby power cables or other electronic devices. If separating the cables improves your picture, use twist ties, tape or cable ties to implement a cable-management system. Try a different cable. The coaxial cable itself may be faulty or poorly shielded. See if using a new cable eliminates the static.
Buy and install an inline cable amplifier. Weak signals are more susceptible to static. Your signal may be weak if you have several TVs split off the same cable signal or if you live in a remote area.
If none of the previous steps solves your static problem, call your cable provider and book an appointment with an engineer to investigate and fix the problem. Depending on the terms of your subscription, some providers may charge for this service.
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Cable TV service
The more devices you chain together, the more static you're likely to have; for example, cable into DVR into DVD player into video game system into TV. Consider using DVI or HDMI inputs for your devices instead of chaining them together via coaxial cable.
Do not open or modify any device that was provided by the cable company. If you believe the problem is coming from your cable box, call your provider for a replacement.