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!

 

Stack exhaust is about 100 cfm more than it should be. The rear blower wheels on the lamphouses themselves are freshly cleaned. One of the reflectors was replaced with new last month...the other is older, but not peeling or flaking. Lenses are 1-year old schneiders.

I am at a loss. The only thing I know to do is to install a heat filter in the built in tray on the MSA head right before the gate. I just don't understand why I have these problems with these two machines, but not with any of our other units.
 

SUPER IMPORTANT!!!!!Also check to see that the exhaust blower squirrel cage is rotating in the right dorection. I have encountered many with the wheel spinning in the wrong direction. The last one I encountered only two weeks ago and it was on a Super 80 running a 3kw lamp! This lamphouse installation had been done 4 years ago too. Reflector is still good though. Lamp life was marginal to the warranty time. Bet they go past 2500 hrs now.
Mark @ GTS
 

And even if i beefed up the stack exhaust, I still don't understand why removing a few hundred cfm more air from the lamphouse will make that big of a difference at the projector gate....especially when I have (at another theatre) a 3K Xenex II unit running with about 450cfm exhaust with no problems...

...also, I was always told not to over-exhaust too much or the lamp would run too cold and cause flicker and short life...is this true?
 

Every time I have had the problem you described it has been the alignment or working distance... is the projector "square" with the lamphouse?

 

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.
 

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.
 

Ask Greg Mueller about the ALIGN-O-TRON laser tool. If THAT cant align it, nothing probably can.

Aaron

 

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.
 

is there anything that I could possibly do about that now (short of returning them to Kneisely). I just figured that if the bulkhead had been moved, then any ill effect from that could be compensated for by adjusting the 4 height adjustments on the (Century) bases to level the optical axis back up with the aperture.
 

You basically need a laser now to line up the two parts of the optical system
 

The compensation would not work because the front support is fixed causing the lamp to be off axis. If I were in you position I would square the reflector to the front of the lamphouse, then center all three adjustment and use a laser, that should get you in the ballbark.