Got a 1080p DLP HDTV the other day off craigslist for cheap ($100, 7 month old lamp, ~35mi away to pick it up). I also saw a 1080p DLP HDTV on craigslist which the owner left on their curb (fully functional), but was a day late in nabbing it. If you're patient I'm sure there are even better deals to be had than what I found.
Anyway, so I opened her up and it looks promising. Haven't taken the DLP engine or any of the boards out yet so I'm not entirely sure what all this stuff weighs, but the TV itself is pretty heavy (Samsung says it weight 75lb's, although I'm not sure I believe it, or maybe that's just 75,
very awkward, pounds
). Would definitely make for a bulky printer, although it might not be too bad with creative mounting of all the boards and ballast and what have you.
Shorting out the optocoupler
should be as easy as any theater projector hack you've seen, although I'll need to take a closer look at the ballast when time allows. I still stand firm in believing a ~60W UVA LED or car headlight mod should be relatively cheap and straight forward when the bulb inevitably burns out.
The projector lens has a fixed focal length. I believe the rear mirror is to a DLP TV as a wall or projector screen is to a theater projector. Due to this I'm imagining I'll have to play with diopter strength and projector distance to get an image that focuses with my desired build dimensions. The lens itself is relatively large (didn't measure it, I forgot to before closing it all back up), but there's a Vivitar diopter lens sent with 86mm diameter for ~$18 shipped on eBay. I'm imagining that's large enough for what I'm doing. The projector lens is also aimed at a ~20 degree angle or so onto the rear mirror (also at an angle). I'll have to figure out if the image is projected as a trapezoid onto the mirror, or if it's rectangular. This will determine whether or not I have to match/offset the lens angle exactly when I mount the engine (in order to attain a perfectly vertical projected beam), or if I have to figure out the mirror's angle and compensate for it when mounting the engine.
I won't have complete control over the dimensions of my build area, a lens set only gets me so far before having to mess with shims and focal length which I don't really want to get into atm (time will tell). But for what I paid? In theater projector talk that money typically gets you 1280×720, maybe less. I'd say as of now this looks like a good budget-minded option for people who don't mind fussing with stuff as behemoth as old DLP TV guts. I'd like to stick with it and see how far I can take it.