can you elaborate on this on/off restriction ? is there a recommended time PJ should be ON and OFF before the next cycle ?
I was reading a thread on this forum about it (can't find it), but apparently the startup of the bulb actually causes a fair bit of wear on it, which is why some recommend that if you're going to be using it like a tv (on/off all the time), you'd be best to stick with a TV. That said, when I go to my man cave to watch a movie or play a game, I leave the pj on even if I have to take a long phone call because it's less stress on the bulb. I also found this (not sure if it's true, but perhaps someone can verify):
For optimum bulb life, wait until the unit is stone cold, absolutely room temperature, before restriking. How long that is varies based on the projector. I use an hour for mine.
The reason it's important not to strike a hot bulb is because the projectors have a pre-programmed voltage ramp that assumes room temperature. I'm not sure if the voltage ramps down or up, but it's designed to take a cold bulb up to operating temperature as safely as possible. If the bulb is already hot, it's hit with the wrong voltages at the wrong time, and that dramatically shortens its life.
I've seen arguments that the cooling fans after powerdown are actually bad for bulb life; it's apparently better to let it cool slowly. But because it's just so, SO bad to restrike while hot, they err on the side of caution and cool the unit as fast as reasonably possible. This stresses the bulb and shortens its life, but it's better than an uneducated user restarting the projector too soon.
Hope that helps.
As far as how long it should be ON before you turn it off, I don't think that really matters. Mind you, I could just be talking with my head up my @$$ (anyone confirm/deny lol).