Problems With Projection TV Pictures

By Larry Simmons

A television experiencing a convergence problem

A projection TV can give a user thousands of hours of enjoyment if used properly with regular maintenance. Unfortunately even the best TV can develop issues, especially with the picture quality. Many of these issues will require the attention of a professional, but some problems are specific to projection TVs and if diagnosed properly can be fixed by an owner without requiring a trip to the TV repair shop.

Quality Issues

If you experience multiple color lines across the screen of your CRT-based projection TV, or the picture is blurry, you may be experiencing a convergence problem. A convergence problem develops because the picture projected on the screen originates in a series of CRT tubes, each projecting a portion of the color spectrum. If these tubes become unaligned the picture does not converge in a single space, and you end up with the blurred picture and multiple color aura distortions. Usually your TV has a test available to correct the convergence on your TV consisting of several lines projected on the screen, which can be moved to place the colors in line with one another and give you a corrected picture.

Sometimes the quality issues are due to the setup of your TV. Adjusting the brightness and contrast of your TV can only do so much for picture quality. In order to get the absolute best you'll have to do a complete picture calibration, which requires the use of a calibration disc. TV calibration is the process of adjusting your set's brightness, contrast, tint, color and sharpness to reference levels that media producers use in the creation of their content. While the disc will cost you about $40, it will result in a picture more consistent with content producer's intentions, and may extend the life of your TV by lowering the average light level output of your set. The two leading DVD-based calibration discs are Avia and Video Essentials, both available from

Lamp Issues

Much of the quality of your TV picture is due to a well-functioning lamp. Most lamps are rated for more than 2,000 hours of trouble-free use, with some of the higher-end designs running as long as 8,000 hours before requiring replacement. You should keep close watch on how your lamp performs as it nears the end of its rating cycle, as age can have a detrimental effect on the picture quality well before the lamp burns out.

A lamp that has had dirt deposits on only one area of the light's surface can develop uneven temperatures in this surface, causing what's known as a hot spot. A hot spot shows on your screen as a spot in the picture that's brighter than the surrounding image. If you've developed a hot spot you should clean the lamp's surface of all dirt and dust. If the lamp's surface hasn't had time to develop a temperature stress point, the hot spot may go away. If it doesn't, the lamp is damaged and the picture problem will continue until your lamp burns out.

Another problem caused by aging of the lamp is a dimming picture. When the lamp nears the end of its life, the picture you see will begin to dim, followed by a distortion of the picture and color skewing. Unfortunately, once your lamp has begun to show these characteristics there's nothing you can do except replace the lamp. Fortunately, once replaced, your picture should be as good as the day you bought the TV.