Generally, a person should read the manual that came with the lamp (at least once) just in case there's something unusual about it that requires you to clean it in a certian way.

But other than that, what I do is..
Our lamps run pretty clean. When it's time to change out a bulb, I remove the old bulb (following safety precautions of course!)

Then I get 4-5 layers of paper towels, unfold them (lay them flat) and soak them with alcohol. I take one wipe only on one side of the reflector; unfold the paper towel (to get a unused side) and wipe the other side. The idea is to not use the same towel layer twice, and risk grinding in dirt. I try to spin my hand like a little film cleaner, picking up dirt and not using the same area of the towel. After those two passes, I get another clean fold and give it an overall cleaning, folding the layers over after a few passes for a clean side. When the layers stay clean, I give it a sort of "polish" wipe.

Before I put the new bulb in, I tighten all those big DC connections, because the heating/cooling cycles always seem to loosen them up. Then, I put the bulb in and spin it with the nipple (the place where the sucked the air out) facing me. In our theaters, that our "code" to tell others that the bulb has not been rotated. When it is facing away, that means someone rotated it.

With the new lamps we have, we have actually stopped rotating bulbs. The glass envelope does not darken very much, and there too little light to be gained, and too much to lose if a heavy-handed person gets in there. Of course, at another theater, it might be well worth the time. We never wipe off the regular dust that gets on a bulb, nor do we wipe off the reflector with a bulb in place. In some dusty parts of the world, this might neeed to be done, but not here in the northeast USA.

Actually, Osram suggests rotating the bulb in 1/4 turn increments (rather then 1/2 turns.) But with less time for maintenance nowadays, we feel the time is spent better elsewhere. YMMV.

I would feel _very_ uncomfortable with a bulb with 10,000 hours on it. My understanding is that the quartz glass could be fractured, and may explode even when cold, when there are too many hours on it. Even if the bulb is running perfect, I will try to get rid of it after about 6000 hours. Not many make it that far (usually they start to flicker), but some do.

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My only comment is on the paper towels -- even softened as explained in the procedures, there is a potential abrasion problem there. We recommend a soft cloth -- t-shirt or diaper material, something like that in lieu of a paper product.

We also try and limit the use of any cleaners except when necessary to remove a stain. Normally, a light dusting with the soft cloth should be sufficient to get dry material off of the reflector.

For a competent projectionist, I do think it's all right to DUST the xenon bulb. Any accumulation of stuff will absorb heat, increasing the work function of the quartz glass it's sitting on. Any stain, accidental figerprint and such on the quartz envelope MUST be removed using alcohol with a cotton swab or soft cloth, using all appropriate care and safety measures.

Great topic!

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General question -- after rotation, have many of you encountered increased flicker? Are you able to alleviate it after some hours of running? Do you increase amperage to get past any initial flickering after rotation, or does the lamp settle down naturally?

I'm curious because my own experience has had mixed results.

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Unscrew the flat lens from the holder (note: I'm referring to the flat lens element and not the entire "lens" that is mounted into the turret).

Fire the lamp and motor. Adjust the left/right, up/down and in/out controls until you get a "bullseye", meaning a nice black center with white "rings" around the black bullseye. This will be fairly obvious and very easy to obtain if your reflector and everything is lined up properly. If you cannot achieve this, call your tech.

Put the lens back in place and switch over to scope. Crank down the in/out focus control until you have a "hot spot" of light on the screen. It should be roughly centered. Fine tune this side to side and up and down with the other two controls until it is centered. Now turn back the focus control until you have an evenly lit screen, as best as possible. Avoid dark corners and an excessive bright spot in the middle of the picture. That's it.

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Of course a *vertical* bulb never needs to be rotated

Aaron

Although you can do a pretty good job of focus and alignment "by eye", the final check should always be actually MEASURING the light level and uniformity on the screen with a screen luminance meter, to be sure it meets standard SMPTE 196M. With really large lamps, it's always a good idea to run a loop made up of dark scenes from an old trailer a few hundred times, to be sure you aren't causing heat damage to the prints.

Pat Moore did a very nice tutorial presentation about lamphouse alignment at the ITEA seminar in Los Angeles this past January.

ALWAYS FOLLOW SAFETY PROCEDURES, INCLUDING PERSONAL PROTECTION IN CASE A LAMP EXPLODES! Likewise, electrical shock is always a risk unless you "lock-out" the mains power and properly discharge any capacitors.

------------------
John P. Pytlak, Senior Technical Specialist
Worldwide Technical Services, Entertainment Imaging
Eastman Kodak Company
Research Labs, Building 69, Room 7419
Rochester, New York, 14650-1922 USA
Tel: 716-477-5325 Fax: 716-722-7243
E-Mail: john.pytlak@kodak.com

If you do that you'll probably fry the print.

I mention it because I've seen this happen more than once.... Maybe there could be a better name that's less misleading to the popper jockeys like, "Don't push this F%$#ING button!"

I keep this piece of film in my wallet just to demonstrate to people what happens if you mess with that button.

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