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This topic comprises 2 pages: 1 2
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Author
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Topic: Xenex II making my gates hot !!!
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Wes Hughes
Expert Film Handler
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Posts: 175
From: Raleigh, NC, USA
Registered: Aug 2001
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posted 08-28-2001 04:51 PM
Hi all...i'm new to posting here. My first post is in "film-yak" "who the hell are you" pg 13.It just so happens that on my first registered day with Film-Tech I have an ongoing problem that I could use any opinions on: On two screens I am running Century MSA heads with the standard curved gate/trap assemblies along with Xenex II lamphouse with 2K lamps. My most severe problem is with the gates getting hot. They film isn't getting scorched, but the gates will give you 3rd degree burns with just a quick touch. The lamphouses were aligned by me (via string). I could not get them perfect, but they are close enough. The little asbestos plate just behind the aperture is in place. The shutter has its cooling fins in place. The lamphouse focus is good. I have tried everything to get the gates to run cooler to no avail. In fact, the whole projector head gets very warm...they have to be regreased often because of this. I have Xenex II's with 3K lamps running elsewhere, and the gates are much cooler there than with my 2K's here, and the projector housing hardly gets warm at all. Another Problem: I have a Xenex I running on another screen that has the exact same throw, screen size, and a 2K lamp. The projector runs cool, and I can get 4 footlamberts more light on the screen than with the Xenex II's! It has been argued to me that the Xenex II is a much more efficient lamphouse than the Xenex I, but I fail to see it. ANY ideas will be appreciated!
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Wes Hughes
Expert Film Handler
![](http://www.film-tech.com/ubbmembers/981.jpg)
Posts: 175
From: Raleigh, NC, USA
Registered: Aug 2001
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posted 08-28-2001 09:53 PM
The working distance is whatever is stated in the manuals (30.5 i think). The adaptors on the bulb were sold to us expressly to use 2K lamps with that lamphouse. I am assuming that if the lamp was sitting in the wrong position (due to incorrect adaptors) that I would not be able to focus the lamp, or that refocusing the lamp would compensate for too short or long adaptors. I mean, there is on ly one "point of focus" that the arc can be manuevered into, right?As far as alignment. Just how fussy are the "deep-dish" reflectors to align? I did these two, and I have to admit it drove me crazy. I spent serveral hours moving them around, and they still are not perfect. One of them is close, but, using the string, it is still not perfect from all directions, and no amount of moving it will help (it will just put it out in another direction). Also, and maybe I should have said this earlier: when I bought the units (used) the bulkhead casting adjustments on top of the reflector were loosened and serveral inches from actual contact with the bulkhead that the reflector is attached to. The installation manuals say that these should never be adjusted since the bulkhead is made to be square with the bottom rails at the factory. They had been loosened. I just tightened them back so that the bulkhead was at a line that the UV radiation from the lamp had burned into the paint on top of the lamphouse...a "shadow" if you will. I don't know what else to do in that department. SO, could the little bit of misalignment that exsists make this big of a deal? ...and if so, how can I align them better (the string thing makes sense, but I cannot get it perfect). Sorry i'm rambling so...but these problems just don't make sense to me.
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John Walsh
Film God
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Posts: 2490
From: Connecticut, USA, Earth, Milky Way
Registered: Oct 1999
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posted 08-28-2001 10:27 PM
I don't know much about Xenex lamphouses, but I do know Century's (JJ's, SA's whatever) gates get very hot. I found there to be very little cooling action provided by shutter. Heat filter are a good idea if you can fit them on. After putting three different lamphouses on the same type of Century projectors, we "gave up" and just installed the water-cooled gate assembly.Now, it could still be some mis-alignment, but generally if the light is even and flat, and checked for optical alignment, I don't think that's the problem (although I feel you might be better off with a laser alignment setup.) I have seen lamps with incorrect xenon adapters still provide flat light, although with much less light than with the correct ones. Double check the adapters are correct.
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Wes Hughes
Expert Film Handler
![](http://www.film-tech.com/ubbmembers/981.jpg)
Posts: 175
From: Raleigh, NC, USA
Registered: Aug 2001
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posted 08-29-2001 01:41 AM
the Xenex 2's have metal reflectors, so they don't pass through UV radiation like the dicro's do...but I agree it's a good idea for any lamphouse to keep both sides of the reflector clean.I am somewhat familiar with laser alignment tools. There used to be a hobbyist here in town that made in his shop but I have yet to use one. Are they expensive? It just seems to me that theoretically a string would work just as good at everything but making sure the anode end is perfectly in line with the aperture (ie that the lamp is optically perfectly in line with the aperture)...with the biggest advantage being ease of use. As far as the adaptors...does anyone know what the proper adapters would be for this lamphouse using a standard length Osram or LTI lamp? We have been using Osram for years, but I have gotten better service out of LTI lamps, so we are switching to them. I have to say that the light is fairly easy to get nice and flat, but with the same lamp, throw, lens arrangement, and screen size I can get more light out of a Xenex 1, which contradicts what I have always been told: that the Xenex 2 is more efficient than the 1. I can only get about 10 footlamberts out of them both.
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