Film-Tech Forum ARCHIVE: Xenon Focus

This is topic Xenon Focus - Christie CH20-CC20 in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Manny Knowles (Member # 1171) on 05-11-2002, 09:45 PM:

I'm having problems focusing the lamp in a Christie CH20-CC20 console. My unit doesn't exactly match the drawing in the manual, so I'm just a little lost.

In particular, my bulb adjustment works different from what is illustrated in the manual. Instead of three things that look like levers all spread out around the back of the lamp, I have a cluster of three bulb adjustment rods with allen-type heads. There's a small access panel to get to them (instead of removing the entire back panel).

The one in the middle (slightly raised) is jammed and so I think I've lost the lateral movement. The one on the right seems to adjust the spread of the beam and the one on the left seems to adjust the vertical position.

So, I'm assuming that the centre one must be for making lateral adjustments. It only moves a tiny little bit to the left and right...is this normal or should I have a great range of movement?

MORE INFORMATION...

This is a brand new lamp and reflector (replacing the one that exploded...see "Xenon Nut Was Overtightened").

I have an Align-O-Tron kit and, according to the little red dot, this projector is a little too high up. (What is the likelihood that this is really the problem?)

Lamp type is XM2000HTP (PerkinElmer).

Ammeter reading is between 70 and 80.

With the lens removed, there are dark spots above/right and below/left of the central spot.

With the scope lens in place, the light on-screen looks yellowish. It's possible to get an even spread, but the color is faaaar from being a bright white.

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~Manny.

Now...where was I ?
Leonard Shelby, MEMENTO.

Posted by Manny Knowles (Member # 1171) on 05-11-2002, 09:56 PM:

Another question: What is the maximum wattage Xenon lamp that can be used in this console. The manual says it will work with lamps from 1000W to 2500W...but as I mentioned, my manual doesn't exactly match what's in my booth.

And while we're on the subject...what's the ideal ammeter reading? I have the tap switch on position 2 right now.

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~Manny.

Now...where was I ?
Leonard Shelby, MEMENTO.

Posted by Michael Rourke (Member # 1142) on 05-12-2002, 01:45 AM:

As far as an ideal amperrage for a xenon there isn't one in particular.

Take a VOM meter and while the bulb is lit measure the DC voltage coming off the positive lead on the diode stack with the other meter lead to ground to get the volts then multiply whatever amps your running at. If you are way under 2000 watts then wrench up the tap and try it out on posiiton #3. Running a bulb too far under current can shorten life, although not as drastically as running over current..Kapow!

I have asked the Christie techs what amperrage is ideal, and they said you should run at whatever gives you 16 footlamberts while still under the maximum wattage of the bulb.

Posted by Gordon McLeod (Member # 33) on 05-12-2002, 10:03 AM:

Depending on the particular rectifier neither the + or neg may be at ground
Check the nameplate for the rectifier in the console base and its output current range
The current should be set within that range and the bulb sized accordingly

Posted by Manny Knowles (Member # 1171) on 05-12-2002, 08:09 PM:

According to the Align-O-Tron, I need to bring the projector head down a bit to align it with the new reflector (and bulb support). I'm thinking that this is the at the root of the lamp focus/screen illumination problem. Anyone else agree/disagree?

The hanger mounts to the console with bolts and then there are various screws (allen type heads) that look like set screws around the edges.

Which (if any) of these bolts/screws will allow me to adjust the height of the projector?

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~Manny.

Now...where was I ?
Leonard Shelby, MEMENTO.

Posted by Manny Knowles (Member # 1171) on 05-13-2002, 12:30 AM:

I just downloaded the manual that's here on this site and the illustrations in that version match my machines more closely.

It is indeed the lateral adjustment that I'm having trouble moving. Not much range at all.

The illustration seems to be pointing to the allen-type screws for projector alignment/adjustment. I just want to be sure about this before proceeding. Unfortunately, the manual doesn't describe how to deal with the adjustment screws...they are on the top, bottom, left and right (all around). Am I supposed to loosen ALL of them or only certain ones for up-down movement?

I'm also curious if there's any danger that the whole projector will just slide on down and fall off...or is there a "stop" on the thing? Sorry if this makes me an idiot, but I've never (ever) had to get this deep into it before.

It seems fairly obvious that this is (at least) a 2-man job, right?

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~Manny.

Now...where was I ?
Leonard Shelby, MEMENTO.

Posted by John Pytlak (Member # 331) on 05-13-2002, 01:05 PM:

The xenon lamp manufacturers usually publish a data sheet for each lamp, listing the recommended operating current range. For example, here is the datasheet for an Osram XBO 2000 W/HS OFR lamp:
http://www.osram.com/pdf/service_corner/technicalinfo/2000WHSe.pdf

Note the rated current is 80 amperes at 25 volts, with an allowed current control range of 50 to 85 amperes.

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John P. Pytlak, Senior Technical Specialist
Worldwide Technical Services, Entertainment Imaging
Research Labs, Building 69, Room 7525A
Rochester, New York, 14650-1922 USA
Tel: +1 585 477 5325 Cell: +1 585 781 4036 Fax: +1 585 722 7243
e-mail: john.pytlak@kodak.com
Web site: http://www.kodak.com/go/motion

Posted by Manny Knowles (Member # 1171) on 05-18-2002, 01:10 PM:

Just a follow-up in case anybody else has this problem in the future.

The problem was/is that the vertical adjustment is frozen in place.

The rear bulb support sometimes has shims. This one had two. Most of the others had one. By removing both shims, I was able to effectively bring the rear support down almost a whole inch.

The focus isn't perfect, but I'm getting much better illumination now.

I'm having someone come in from Miami to do some heavy-duty repairs to another console, so I'll wait until then to get the vertical adjustment corrected.

------------------

~Manny.

Now...where was I ?
Leonard Shelby, MEMENTO.