Film-Tech Forum ARCHIVE: Lamp life

This is topic Lamp life - lamp strike in forum Digital Cinema Forum at Film-Tech Forum ARCHIVE.

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Posted by Nils Hoover (Member # 6636) on 11-21-2012, 03:05 PM:

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.

Posted by Bajsic Bojan (Member # 4928) on 11-21-2012, 03:38 PM:

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]

Posted by Carsten Kurz (Member # 5396) on 11-21-2012, 07:14 PM:

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

Posted by Scott Norwood (Member # 30) on 11-21-2012, 08:08 PM:

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).

Posted by Victor Liorentas (Member # 5272) on 11-21-2012, 08:32 PM:

I also keep the lamp on for 20 min reels or a 20 min intermission but longer than 20 I shut it off.

Posted by Olivier Lemaire (Member # 5579) on 11-21-2012, 10:00 PM:

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.

Posted by Steve Guttag (Member # 268) on 11-22-2012, 06:27 AM:

Note...if you have the Cinedigm TMS...you 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).

Posted by Joris Springer (Member # 4175) on 11-27-2012, 08:04 PM:

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.

Posted by Victor Liorentas (Member # 5272) on 11-27-2012, 09:51 PM:

Your problem could be Osram itself [Smile]

Quality of Osram lamps has been shaky for quite awhile.
Christie/Ushio lamps are incredible in comparison.