What Is Wrong if My Projection TV Has No Picture but Just Sound?by Tyson Cliffton
While some new, high-resolution projection TV models based on DLP technology have been introduced to the 3-D home theater market in 2010-11, most projection TVs still in use in late 2011 are an older technology that doesn't offer the sharp resolution of the newer plasma and LCD TVs. If you are getting sound from your projection TV but can't see a picture, a variety of issues could be at fault. The most common are traced to the lamps that project the image. Most loss of picture issues can be found and resolved with a little troubleshooting.
Reseat or Replace the Lamp or Bulb
A lamp or bulb is required to display the image in a projection television. These lamps may dim over time and then go bad or die suddenly. Before you decide to replace the lamp, try reseating it. The connection can loosen over time, resulting in no picture display. If reseating the lamp does not work, replace it. You often can get a new lamp or bulb through a store that specializes in televisions, or directly from the manufacturer.
Change the channel on your projection TV if a high-definition channel you are pulling in over the air has gone black. If only one channel has the problem, the trouble is probably at the transmitting station rather than with your TV. If the problem is the same on all of the HD stations you are pulling in over the air, try moving the antenna to check if anything is blocking it from receiving signals. Position the antenna away from other electrical devices and so it is not pointing toward large obstacles outdoors. Make sure the antenna's cable is firmly connected to the TV. Standard definition channels pulled in over the air will experience a great deal of static if the signal is blocked, but the video will rarely drop off entirely.
Make sure the video cables associated with external devices connected to the projection TV are securely connected to the appropriate inputs on the TV. If there's a possibility something is wrong with a cable, try using a different cable of the same type to connect the external device to the TV. Switch to a different video output and see if the problem is the same.
Reset the TV
The TV may suffer a glitch as a result of a power outage, being moved, or some other disturbing event. To reset your projection TV, unplug it from the power outlet for at least three minutes. Plug it back in and turn the TV on to see if the problem has been resolved.