It need to be connected to a signal source, like the video output from your computer or a TV receiver.
If to a computer, the computer also need to be turned on.
If it's connected to your working computer and it still say "No signal", then there is probably a problem with the cable, or the connector used is somewho disabled. Try another cable.
Check the video settings. Check the material configuration.
Electro, August 2012
