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» Film-Tech Forum   » Operations   » Film Handlers' Forum   » Rotating Xenons? Pro or Con? (Page 1)

 
This topic comprises 3 pages: 1  2  3 
 
Author Topic: Rotating Xenons? Pro or Con?
Michael Rourke
Expert Film Handler

Posts: 159
From: San Luis Obispo, Central Coast of CA
Registered: Feb 2002


 - posted 04-11-2002 11:25 PM      Profile for Michael Rourke   Email Michael Rourke   Send New Private Message       Edit/Delete Post 
I was taught to rotate at half life, and then some time later I was told that it really doesn't matter. Then again some time later I was "strongly advised" NOT to rotate bulbs. Then I read on this site from various operators that they have bulbs going 6,000 hours with 5 rotations mixed in. Who is right? I notice also that bulbs don't have the nipple on the envelope anymore, is this to discourage rotating?

I ask because I have been having tons of problems with my bulbs since I stopped rotating, plus we switched from Osram to ORC (not happy), and I have had problems with bulbs fusing to the negative end clamp on my Christie SLC's.

I am trying to gather enough evidence against ORC to get my superior to make another switch either back to Osram or to Christie xenons. I have already printed out the ORC Xenon bulb review on the site, and some testimonials would help too. Thanks.

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Ian Price
Phenomenal Film Handler

Posts: 1714
From: Denver, CO
Registered: Jun 99


 - posted 04-11-2002 11:31 PM      Profile for Ian Price   Email Ian Price   Send New Private Message       Edit/Delete Post 
I never rotate my lamps. Please refer to the previous thread titled Lamp Rotation

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Paul G. Thompson
The Weenie Man

Posts: 4718
From: Mount Vernon WA USA
Registered: Nov 2000


 - posted 04-11-2002 11:49 PM      Profile for Paul G. Thompson   Email Paul G. Thompson   Send New Private Message       Edit/Delete Post 
Michael, if the bulbs are fuseing on the negative end, I would highly recommend that the collar be tightened in accordance with the manufacturer's recommendation upon installation of the bulb.

It might be a good idea to inspect that area perodically to make sure they are tight.

If the bulbs are turning black, I would rotate them at half-warrenty life.


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Michael Rourke
Expert Film Handler

Posts: 159
From: San Luis Obispo, Central Coast of CA
Registered: Feb 2002


 - posted 04-12-2002 12:04 AM      Profile for Michael Rourke   Email Michael Rourke   Send New Private Message       Edit/Delete Post 
I replaced all the negative end clamps (even those that weren't fused to a bulb) and all the cathode leads as well.

I was told not to overtighten the socket head allen on the clamp or the bulb would fuse, but then when I took my reoccuring problem to Christie they told me to really wrench down on that screw.

Thanks Ian for informing me of the related post, I promise to use the search feature in the future.

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Paul G. Thompson
The Weenie Man

Posts: 4718
From: Mount Vernon WA USA
Registered: Nov 2000


 - posted 04-12-2002 01:34 AM      Profile for Paul G. Thompson   Email Paul G. Thompson   Send New Private Message       Edit/Delete Post 
Yes....heavy current flow through a loose or snug mechanical connection will cause plenty of heat. It'll get hot enough to weld itself to the other part.

Anytime a bulb is changed, the critical parts should be examined for evidence of pitting or overheating. If this condition exists, you can tighten things down until you are blue in the face, only to find later that the situation has gotten worse.

The parts that show overheating and pitting should be replaced. If the parts are not available, at least clean them up if at all possible. Lousy mechanical connections will probably void the warrenty.


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Don Sneed
Master Film Handler

Posts: 451
From: Texas City, TX, USA
Registered: Aug 2001


 - posted 04-12-2002 04:27 AM      Profile for Don Sneed   Author's Homepage   Email Don Sneed   Send New Private Message       Edit/Delete Post 
I have been told not to rotate a bulb, some manules say it is not needed.....I say "YES IT DOES" .... I tell everyone we install for to rotate the bulb 1/4 turn every 500 hours to burn the anode & cath. evenly, if you don't the bulb will flicker due to the anode & cath. burns unevenly which will cause the flicker, at 500 hours, turn 1/4 to prevent this....even bulbs that starts to flicker, by turning 1/4 or even a little bit more in most cases after a couple of days the flicker will be down to a minim or gone, if that don't work, turn a wee bit more, agin after a few days it should be back to normal, not in all cases but the majority will work it out & start to burn evenly..now of course this is only for the Horizontal lamps not the vertical, there is nothing that can be done about those accept to change them....by doing this rotating, you can get 3,000 to 6,000 hours easly from the bulb.....

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John Pytlak
Film God

Posts: 9987
From: Rochester, NY 14650-1922
Registered: Jan 2000


 - posted 04-12-2002 07:23 AM      Profile for John Pytlak   Author's Homepage   Email John Pytlak   Send New Private Message       Edit/Delete Post 
Rotating a horizontal xenon lamp usually does help to even out the electrode wear and the blackening of the envelope as the lamp ages.

Electrical contacts need to be tight. Any resistance at the contact will cause a voltage drop and heating, and may "weld" the contact.

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


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Mark Gulbrandsen
Resident Trollmaster

Posts: 15885
From: Bountiful, Utah
Registered: Jun 99


 - posted 04-12-2002 09:14 AM      Profile for Mark Gulbrandsen   Email Mark Gulbrandsen   Send New Private Message       Edit/Delete Post 
With me it depends on if there is someone at a given location that is capable of rotating a lamp correctly or not. I service a number of locations that do not have anyone with sufficient ability to do this correctly. At these locations they leave them alone and do not rotate them. At other locations that I do have rotate lamps they don't seem to get any more or less hours out of them than the locations that do not rotate them. We sell only Ushio(Christie) lamps and the high quality of these lamps may have alot to do with that. Typically we see at least 4000 hours from a 2kw lamp, although I don't reccommend it. I have a number of customers that are adamant about changing them at the end or rated life which is 2500 hrs. One thing I do reccommend is to rotate larger lamps starting at 3kw every 500 hrs. Typically, one can get 2K hours from a 2.5K or 3K lamp this way.
Mark @ GTS


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Pat Moore
Master Film Handler

Posts: 363

Registered: Mar 2000


 - posted 04-12-2002 09:45 AM      Profile for Pat Moore   Email Pat Moore   Send New Private Message       Edit/Delete Post 
I tend to come down more on Mark's side of this. Experience has taught me that there is no hard & fast single answer to the question.

The theory of rotation and why to do it is fine and logical. But I hear a lot of reports about unstable arcs and increased arc waver after rotation, especially when that's done at half-life. Supposedly you can run the lamp at a higher current, near its maximum for a few hours, and the arc will generally settle down. I've seen instances where that does work and others where it doesn't.

I like the quarter-turn at quarter-life idea a little better. I like rotating the lamp if there is obvious darkening of the quartz on the top-half of the envelope a little better than that.

The best for me is if: a) the lamp arc is not wavering, and b) the quartz is clear, then don't fix what isn't broken. The lamp is "happy", let it run.

I think Mark's statement about the capability of the booth staff to do this and monitoring the results is probably the most important factor.

Pat

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John Pytlak
Film God

Posts: 9987
From: Rochester, NY 14650-1922
Registered: Jan 2000


 - posted 04-12-2002 12:51 PM      Profile for John Pytlak   Author's Homepage   Email John Pytlak   Send New Private Message       Edit/Delete Post 
Pat:

I agree with your concerns. But if electrode wear/sag has progressed to the point where simply rotating the lamp compromises performance, it's obvious that the wear is uneven. Perhaps the solution would be rotating on a more frequent schedule?

Hard to argue with the point that many theatres today do not have anyone on staff that have the knowledge and skill to properly and safely rotate a lamp, and then readjust the alignment for optimum light output.

BTW, are lamp mount shims available to allow a 90-degree rotation? Are they normally supplied by the lamphouse manufacturer, or the lamp manufacturer?

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

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Darren Briggs
Master Film Handler

Posts: 371
From: York, UK
Registered: Dec 2001


 - posted 04-12-2002 01:00 PM      Profile for Darren Briggs   Author's Homepage   Email Darren Briggs   Send New Private Message       Edit/Delete Post 
Well I run 2k lamps and rotate them every 500 hours, I was taught this and the theory behind it sounds good to me. If a lamp gets to 2500 hours and starts to flicker, doing the rotation normaly cures this.
After 3000 hours, the next time they flicker I replace them, as I would rather not have too lose a show due to a xenon going out and refusing to re-strike. So in a single projector screen running on average 4 shows a day, I get 6 months from a 2k OSRAM.

Darren

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Bernard Tonks
Jedi Master Film Handler

Posts: 619
From: Cranleigh, Surrey, England
Registered: Apr 2001


 - posted 04-12-2002 01:16 PM      Profile for Bernard Tonks   Email Bernard Tonks   Send New Private Message       Edit/Delete Post 
I’m a great believer in rotating bulbs after 1000 hours, average life on a 2Kw was 2500 hours.

Yes Osram always supply a washer to enable a 90 degree rotation.



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Scott Norwood
Film God

Posts: 7867
From: Boston, MA. USA (1774.21 miles northeast of Dallas)
Registered: Jun 99


 - posted 04-12-2002 02:53 PM      Profile for Scott Norwood   Author's Homepage   Email Scott Norwood   Send New Private Message       Edit/Delete Post 
As another data point, I recently replaced a 2k Osram XBO which had just begun to flicker at about 3800 hours. It had not been rotated at all. This was in a recent-vintage Strong Highlight-II console with excellent ventilation. There was some uneven blackening, but the image on screen had looked fine up until that day.

On the other hand, at another theatre, it is rare to get more than 2000 hours out of the same Osram 2k bulbs in older Christie lamphouses (the ones they made in the late '70s/early '80) with somewhat questionable ventilation.

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Michael Rourke
Expert Film Handler

Posts: 159
From: San Luis Obispo, Central Coast of CA
Registered: Feb 2002


 - posted 04-12-2002 05:51 PM      Profile for Michael Rourke   Email Michael Rourke   Send New Private Message       Edit/Delete Post 
To the guys that rotate every 500 hours: How many screens do you run?

I don't know if I could keep up with all that bulb maintennance with 11 screens, especially since 4 of those screens weren't being run by projectionists for 7 years and need a lot of work.

I was taught to have the "tit", "nipple" whatever at 3:00 or 9:00, and then rotate at half life. I was told NEVER to have the "tit" at 12:00, and I was never told about increasing the wattage after rotation. Like Brad, I am just running as close to 100% of the bulb wattage from start up to finish, but I think the ORC bulb aren't fans of this method and have yet to wow me with prolonged performance.


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John Walsh
Film God

Posts: 2490
From: Connecticut, USA, Earth, Milky Way
Registered: Oct 1999


 - posted 04-12-2002 05:56 PM      Profile for John Walsh   Email John Walsh   Send New Private Message       Edit/Delete Post 
At the risk of repeating myself (and others) good ventilation makes bulbs last longer. We're doing about 800cfm on even 2K lamps, and getting great life; easily paying back the price of bigger ducts and fans required. For a problem lamp, experiment by asking your HVAC guy to install the largest fan allowed, and track bulb life.

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