If you're using an Apple notebook, confirm the AC power cable or adapter is securely connected to the computer and the cable providing power to the display is also secure.
When using an external display be sure to check the following: No video or no signal, image distortion, 'snow,' or flickering To start troubleshooting this issue where your TV is showing No Signal with your MacBook Air plugged in, please follow the troubleshooting steps below. Thanks for using Apple Support Communities.
