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Author
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Topic: Converting projectors that use expensive DJL bulbs
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Steve Klare
Film Guy
Posts: 7016
From: Long Island, NY, USA
Registered: Jun 2003
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posted October 12, 2014 09:29 PM
I buy EFPs and EFRs which are pretty cheap, so I actually buy three of each at a time and stash them. This is enough for several years.
-one night last week I blew one of each on my two machines: just wasn't my day!
With a scarce bulb, it's probably not going to get any more common, so when you get the opportunity to grab a couple it's probably a good idea to stock up several spares.
If someday you decide you don't need them you'll be able to sell them for at least what you paid and maybe even more.
I don't necessarily agree with the "cool the bulb off with the fan after use" philosophy. When I used to work in avionics we talked about Thermal Shock: rapidly heating and cooling a device so that all the different parts expanding or contracting at different rates tended to tear each other apart.
To me the opposite of that is letting something cool down as slowly as practical and not running a stream of cool air across it while it's still hot.
I remember my Dad doing this with his slide projector, but I think his idea was the lamp was more fragile while it was hot and he wanted it cool before he moved it. (Don't really agree there either.)
(I suspect it doesn't make much difference either way, the filament will fail before thermal stresses take over.)
Edit: I'm seeing these lamps at about 60 bucks a pop where I buy mine. If you take the money for three lamps you can buy a pretty decent Elmo or Eumig sound machine that uses 50 hour lamps you can get for less than 10 dollars (just a thought)
[ October 12, 2014, 10:37 PM: Message edited by: Steve Klare ]
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All I ask is a wide screen and a projector to light her by...
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Steve Klare
Film Guy
Posts: 7016
From: Long Island, NY, USA
Registered: Jun 2003
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posted October 13, 2014 08:02 AM
It depends on what you mean by "hot". The thing is white hot when it's operating, but cools to orange and red and then out in what, two seconds? I wouldn't bang it around while it's operating, but probably if you do a normal take down and then put the projector away a few minutes after you last lit the lamp you are good to go, especially if you remember the whole thing is delicate anyway even stone cold.
You don't let it sit an hour, declare it cool enough and then take it skiing!
I'm saying Dad's post-show ritual made him feel happy, and that's fine. Other than that I doubt it made much difference. I'm also saying running the fan probably put more stress on the envelope than not using it would have, but the filaments died a natural death long before the stresses made a difference anyway.
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All I ask is a wide screen and a projector to light her by...
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