Checking the website of the TV manufacturer, visiting electronics or repair sites that host manuals, calling the store where you originally purchased the TV or purchasing a repair book from a bookstore or an online retailer are ways to obtain a troubleshooting and repair guide for a projection television. Visiting used electronics stores can sometimes yield results as well, as they may have older manuals that have since gone out of print.
A lot of TV manufacturers do not print full manuals anymore in an effort to reduce printing and paper costs. However, they often have full troubleshooting guides on their websites as a PDF file that you can download to your hard drive. You need the correct model number for your projection television to find the right one. If that fails, call the customer service line for the manufacturer to see if you can have a full manual sent to you. There may be a fee for this service.
Repair guides are often not provided to consumers by the manufacturer, because attempting repairs yourself can damage the equipment if you do not know what you are doing and void any remaining warranty. However, there are various e-books and hard copy manuals available through local bookstores or sites like Amazon that provide full instructions for how a projection TV works and what to do when something goes wrong or needs replacement.