Originally Posted by huecodoc
.... for which I now take planned 15 minute "intermissions" with the projector off in the middle of every film.
BTW... this is typically a bad idea. Every time the lamp is ignited, the initial "spark" that's required to initiate the arc/plasma - blasts off a minute amount of electrode material... permanently. (this material then adds to the "dark cloudy" look that begins to dim the lamp output, as well as add to the internal heating of the lamp... which will lead to the eventual total lamp failure)
In the large projectors that I maintain at work (a large church in KCMO), the manufacture gives a number to the effect of "every lamp strike effectively reduces the overall lamp life by 10-20 hours".
In other words, the amount of electrode material that's destroyed upon each and every lamp strike, would normally take 10-20 hours of lamp ON time to erode.
As the electrodes are blasted away, that effectively increases the gap distance between them, making it harder for the lamp igniter circuit to throw a hot enough voltage to create the initial spark, and thereby generate the plasma burn.
This is why I always instruct all staff members who borrow one of the loaner projectors at work... "If you need to set up the projector up-to 2 hours or so before your event begins, leave the projector ON until your event is over, as this will do less damage than turning it ON for just the few minutes it takes to set up." I do this at home as well... after my boys finish their movie, I ask them to leave it ON if I'm going to use it after they go to bed, 2-3 hours later. My current projector (a Studio Experience HD20) has served me VERY well for 7 years, with each lamp lasting WELL over the advertised hours.
(BTW... I'm cruising 'here' because I just bought a "needs repair" PT-AE2000 on eBay... praying/hoping it will be a simple repair!)
Arc lamps are finicky... I've been repairing/rebuilding video projectors ever since the Sharp XG-E650UB I had probably 14 years ago.
MERRY CHRISTMAS TO ALL, AND TO ALL A GOOD NIGHT!