I happen to have a stack of old Phillips 3 lcd projectors, the ones i repaired work great... but only until the uhp bulbs burn out and at a hundered bucks a pop minimum to replace, probably more considering the age of the projectors its really not worth the price
Now if i were to replace the uhp bulb and high voltage board with a high power led for a fraction of the price that would be worthwhile, especially considering how much longer the led will last compared to the 2000 or so hours from a uhp lamp.
Some quick poking around the insides of any of the projectors resulted in a 3 wire connection from the high voltage supply to the control board. Probing with a dmm showed 5 volt signals, further probing with an oscilloscope showed that the control board pulses a high signal to start the hv board which gives a constant low while the bulb is running. While the bulb is active the control board gives a continuous pulsed signal, when that signal stops the bulb is turned off.
Pretty straightforward so far, 40 $ worth of parts are on their way and i have already figured out how i am going to implement control using a pic micro controller.