The following steps will help you diagnose whether your issue is a problem with the TV or the device broadcasting the picture.
Step 1: The first step you need to perform will be to narrow down whether the issue is being caused by the TV or by a device. To test this, open the Menu on the Television. Is the issue occurring over the menu?
Step 2: Check to make sure the cord is securely connected to the device and the TV. If a cord comes loose it could cause a display issue.
Step 3: If the issue doesn’t appear over the menu, it may be a problem with that device. Try using another device to view video. (Example: if the issue happens on a cable/satellite box, try using a DVD player or gaming system to see if the issue occurs there)
Does the issue occur on a second device?
(Example: If the issue only occurs when you watch your cable box, but not your Blu-Ray player or gaming system, the issue is probably with the cable box. If the TV was malfunctioning it would present the issue on all of the devices.)