My samsung projection tv picture is going dark

Hi

the main reason is could be that you lamp is old and needs to be replace, Phillips lamps will give you from 6,000 to 8,000 lamp hours and if you get a generic lamp that will give you from 3500 to 4500 hours let me give you an insite of the lamp technology:
Background UHP Lamps are used widely in DLP and LCD projection displays. The lamps are not extremely complicated
and provide a light source for your television or projector display. Philips lamps have very low failure rate
and are often blamed for another faulty component such as a bad ballast, color wheel, light engine, or
cooling unit. The lamp itself is encased in an enclosure, meant to hold it in place and connect it to the ballast. How It Works The lamp itself typically uses AC current and about 15,000 volts to ignite the lamp's mercury vapor gas. The gases inside the lamp react when electricity charges up the mercury gas creating very bright light. The voltage drops to keep the flow of electricity to the lamp. The lamp works with the ballast to project light into a light engine that separates the colors of the light, then recombines them with an image. The image is then reflected on the back of the TV and then onto the screen. So in other words more likely your lamp needs to be replace ,and you can find this lamps at http://www.purelandsupply.com/Samsung-DLP-TV-Lamp.html or ebay or http://www.discount-merchant.com/SearchResults.asp?Search=samsung%20lamps?click=52978 please keep us posted and good luck Samuel