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» Film-Tech Forum   » Operations   » Digital Cinema Forum   » Lamp life - lamp strike

Author Topic: Lamp life - lamp strike
Nils Hoover
Film Handler

Posts: 17
From: Ithaca, NY, USA
Registered: Nov 2011

 - posted 11-21-2012 03:05 PM      Profile for Nils Hoover   Author's Homepage   Email Nils Hoover   Send New Private Message       Edit/Delete Post 
I understand that turning on a lamp (of any kind, but in particular a DCP bulb) causes some stress on the bulb, and in a sense lowers its lifespan. About How many operating hours of life do bulbs lose when turned on?

I read a post here somwhere that said it is about 1 hour (and in that sense, less than an hour between content, and the bulb would be better to stay on).

Just making sure I am setting up my systems in an efficient way. Any source to some sort of tech spec article if they exist would be great.

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Bajsic Bojan
Expert Film Handler

Posts: 188
From: Ljubljana, Si, Eu
Registered: Aug 2008

 - posted 11-21-2012 03:38 PM      Profile for Bajsic Bojan   Email Bajsic Bojan   Send New Private Message       Edit/Delete Post 
Since we're digital now, we can actually get some data on this as all projectors keep info on how many times the lamp was struck! Which we couldn't do on 35mm where we usually estimated the amount.

Would be nice if everyone posted some numbers of their lamps at the end of their guarantee cycle (cannot do it for me as we're on our first lamp, about 65% deep).

But based on previous video pj xenons and 35mm xenons, i would say a xenon is a xenon is a xenon. A strike every 120 minutes and it will work as long as specified and more. A strike when its hot, probably take two hour or more out for every strike. Cinemas here that run changeover rather use (despite some bad exhaust) 4000 ft reels then running reel by reel as that does add up in strikes, lamps seem to handle the '1 strike per 40 minutes' better than '1 per 20'.

Saw the same patterns with my previous changeover booth and all my previous video projectors. People with more mileage may answer different [Smile]

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Carsten Kurz
Film God

Posts: 3866
From: Cologne, NRW, Germany
Registered: Aug 2009

 - posted 11-21-2012 07:14 PM      Profile for Carsten Kurz   Email Carsten Kurz   Send New Private Message       Edit/Delete Post 
Ushio did some educated tests, and what they found out is that the magic number is around 10-15min. That is, you should switch of the lamp when your expected pause is longer than 10-15minutes. If shorter, leave it running. Hot-striking is bad for xenons.

- Carsten

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Scott Norwood
Film God

Posts: 8002
From: Boston, MA. USA (1774.21 miles northeast of Dallas)
Registered: Jun 99

 - posted 11-21-2012 08:08 PM      Profile for Scott Norwood   Author's Homepage   Email Scott Norwood   Send New Private Message       Edit/Delete Post 
In practice, lamp life is only part of the issue. I always leave both xenons on when running 2000' changeovers, since this avoids the potential embarrassment of having a lamp fail to strike at changeover time. Also, xenons usually take about 3-5 minutes to come to full brightness, and therefore leaving them on for the show gives more consistent light than constantly powering them on and off.

I might feel differently about really high-powered lamps, but I will leave anything up to 4kw on for the duration of the show.

I thought that this was standard practice, anyway. I don't know anyone who regularly strikes a xenon for every reel change, unless forced to (e.g. by some Kinoton equipment that switches the lamp with the motor).

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Victor Liorentas
Jedi Master Film Handler

Posts: 797
From: london ontario canada
Registered: May 2009

 - posted 11-21-2012 08:32 PM      Profile for Victor Liorentas   Email Victor Liorentas   Send New Private Message       Edit/Delete Post 
I also keep the lamp on for 20 min reels or a 20 min intermission but longer than 20 I shut it off.

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Olivier Lemaire
Expert Film Handler

Posts: 118
From: Paris, Ile de France, France
Registered: Jan 2010

 - posted 11-21-2012 10:00 PM      Profile for Olivier Lemaire   Author's Homepage   Email Olivier Lemaire   Send New Private Message       Edit/Delete Post 
Feedback from a circuit of about 100 screens, running Christie (Serie-II) and CDXL lamps (so Ushio in fact), for around 4 to 6 show/day:
* strike lamp at "morning" (just before 1st show - a dedicated Show Play List to init all the stuff around and the Xenon)
* show - never xenon off
* xenon off after last show (a dedicated Show Play List to turn off the xenon and all the stuff around).

Inter-show are generally around 15 to 30 minutes (max 1 hour).

Projectors are less than 2 years old. Extraction and climers are ok.

Lamps are change well over their 100% warranty aging - even 6kW lamps (example: CDXL-60 are changed from 700 hours to 900 hours...).

From what I saw so far with Ushio CDXL "standard" and SD bulbs, a strike could mean around 2 hours of real usage (of course depending on the condition - striking a hot bulb will be worst than striking a cold one).

We don't have enough feedback yet on SP "bulbs" series.

Hope this'll help.

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Steve Guttag
We forgot the crackers Gromit!!!

Posts: 12298
From: Annapolis, MD
Registered: Dec 1999

 - posted 11-22-2012 06:27 AM      Profile for Steve Guttag   Email Steve Guttag   Send New Private Message       Edit/Delete Post 
Note...if you have the Cinedigm can set the intermission time that will trigger when the lamp is left on. I typically set it to 20 minutes (any intermission shorter than 20 minutes and the lamp stays on...with theatres that run ads, that is often the case).

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Joris Springer
Film Handler

Posts: 83
From: Almere, Flevoland, The Netherlands
Registered: Feb 2007

 - posted 11-27-2012 08:04 PM      Profile for Joris Springer   Email Joris Springer   Send New Private Message       Edit/Delete Post 
Well, first of all I would not keep the Xenon on all day, not only do the manufacturers advice against it (who would know, lamps make more hours, should be replaced sooner and yet they don't say you should do that ;-) )

One of the engineers from the Xenon department at Osram had time to explain to me the following: the lamps are build for a 1:1 ratio, a lamp of 1000 hours should reach at least 1000 strikes, just as long as there is 20 minutes between the end of the show and the next strike.

The manufacturers also say that keeping the Xenon on for long periods of time will cause disruptions in the picture, unstable flame in the lamp, fluctuations on the screen, which we have seen happen.

Also keeping the lamp on all the time will not stop the "lamp strike error" or the lamp failing during shows from happening, the cause is something else.

I do not know what is causing it, just that it is very frustrating and taking a lot of time and that I wish I knew an answer. But so far I do not. Because I did try keeping the xenon on all day long, our projectors are almost 1 year old and well, so far I think maybe 10% of our lamps have reached the last year the hours that they should.

From the booths that have had a stable run so far we keep the lamps in until they reach those hours and the tail light turns blue, not wanting to risc the chance of similar problems. We are not using CDXL lamps but the situation is I think comparible.

We have the most problems with 4kw and 3kw lamps btw.

Also Osram advices to let the lamp cool down for at least 20 minutes before striking again which we mostly keep in mind, sometimes we are forced to leave the lamp on or need to make other shows.

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Victor Liorentas
Jedi Master Film Handler

Posts: 797
From: london ontario canada
Registered: May 2009

 - posted 11-27-2012 09:51 PM      Profile for Victor Liorentas   Email Victor Liorentas   Send New Private Message       Edit/Delete Post 
Your problem could be Osram itself [Smile]
Quality of Osram lamps has been shaky for quite awhile.
Christie/Ushio lamps are incredible in comparison.

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