Hi Peccavi,
Try changing the internal fuse. Powering-up problems can sometimes be as simply fixed as that. You need to give more info on your problem, as well as your make and model, to get more helpfull answers.
Dave, November 2009
Big job - you need to get to learn some of the basics of electronics - become proficient with hand tools, test equipment , reading schematics. Develop some troubleshooting and diagnostic techniques. First though you need work out the make & model of your projector.
Peccavi, November 2009
edit
I can answer this question...
HOW CAN I FIX A NEW POWER SUPPLY FOR MY PROJECTOR?