If the issue only occurs using a cable box, then the cable box may be the issue. Likewise, if the noise doesn't occur when using the built-in tuner of your TV, or when you change video inputs, the issue isn't on your TV.
Some cable or satellite set-top boxes allow the user to select a specific output setting. Change the following output settings on the set-top box:
- Video output: 1080i
- Audio output: stereo, PCM, or LPCM
- 4 x 3 Override: Off
- You may need to restart or reboot the set-top box after you make the changes above.
- Contact your cable or satellite service provider for model-specific information and further troubleshooting steps.