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This topic comprises 2 pages: 1 2
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Author
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Topic: Christie CDXL-30 and -20 lamp issue, anyone else?
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David Zylstra
Master Film Handler
Posts: 432
From: Novi, MI, USA
Registered: Mar 2007
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posted 06-13-2008 02:46 PM
Over the past several months I have been tracking seveal Christie CDXL/CXL lamp performance in our digital projectors.
So far both the CDXL-30 and CDXL-20 have been removed from service early due to low light output.
The facts: All projectors are Christie CP2000H CDXL-20 - when installed the max onscreen was 18FL (at 110% power), 14FL was initially reached with 90% power, after the 500 hour mark the lamp was running at max power (110%) and only hitting 12FL, now at the 950 mark the lamp is only able to hit 9FL. When I calculate the lumen output this lamp started at just over a max of 8,000 lumens and now at only 40% of its warranty life the max is just over 4,000 lumens (this lamp is estimated at 9,000 lumens in our projectors). This same drop has been noted with 2 CDXL-20 lamps in the same projector, CFM is running at just about 600 (the required minimum). The next step is to verify this drop with another CDXL-20 in a different projector. CDXL-30 - when installed the max was hitting 24FL, this lamp saw a small, quick drop and then maintained 14FL at 93% for 600 hours, then stabilized at 100% for 300 more hours, now at 1,000 hours (70% of warranty life) the lumen output has dropped 60% (when installed 13,500 and now only 5,000). This same drop has been noted with 2 lamps in 2 separate projectors. Cooling for both has been verified at a minimum of 600CFM each.
I am gathering data from other lamp sizes, but so far none of those have become unusable.
A few notes: The Christie projectors report power in % of a given lamp size's rated amperage - i.e. you tell it the lamp is a 2000 watt model and internally it knows the proper amperage range. All my data has been emailed periodically to many departments at Christie so they are aware of my results, so far no response on why these 2 lamps seem to be poor performers. So far the other lamps are performing well and have not seen as significant a drop as the above 2 lamps (CXL-30, CXL-45, CDXL-45 and CDXL-60) I'm using a Sekonic L758Cine (similar to the ones issued to Christie techs) - margin of error on the readings is +/- .5FL (yes, not the best but it works). The idea of my data is NOT to prove with accuracy the actual lumens of each lamp, but rather to show what the drop in output will be so I can properly size lamps for each screen (and the manufacturer claims there is no similar data available). A CXL- type lamp in the same projectors as the above lamps maintains output much better over the life of the lamp (so there can't be too much wrong with the projectors in question).
To answer the obvious question - yes, the autofocus procedure has been run periodically on each lamp.
I'm curious if anyone has seen anything similar with these 2 lamps? With these lamps in other digital projectors? Anyone tried them in 35mm?
I apologize for such a long post.
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Steve Guttag
We forgot the crackers Gromit!!!
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Posts: 12814
From: Annapolis, MD
Registered: Dec 1999
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posted 06-13-2008 09:16 PM
I've been doing quit a bit of research myself on xenon lamps (including the CDXL line).
In some ways, xenon lamps behave a lot like LEDs...if you run them hard they will decrease in lumen output faster. Thus, if you start a lamp at the bottom of its range, it is likely to last a lot longer. Furthermore, as the lamp ages and you increase the current, it will progressively go down.
However, all xenon lamps experience a degree of "burn back" which normally occurs within the first 100-hours. It is TYPICAL of most xenon lamps to drop 20% of their light output within the first 100-hours..
I have certainly tested lamps that were faster than this and certainly tested lamps that were slower...but on average, without knowing the characteristics of a specific model lamp, 20% decrease in the first 100 hours should be expected. Thus, if you have a lamp running at 80% of its rated power at the get-go...it will be up to 96% by 100-hours (20% of 80%).
Typically, after the initial burn back you will get a much more gradual fall off.
I have seen some lamps where the light increased into its life! As the arc changes due to the electrodes wearing, how that arc works with the reflector and lens optics can improve or degrade.
I do not have a lot of experience with the CDXL-20 yet though I have a projector using it now...it is operating towards the bottom of its operating range though.
Christie has been pretty up-front with their CDXL specs. The CDXL-20 SHOULD get about 26% more light than the CXL-20. So, if the CXL-20 got you 14fL...the CDXL-20 should send you up to 17.64fL. Some may not see that as too big a deal. However, you will run the lamp at 14fL...thus turn the current down...this will start the CDXL on what should be a longer life in the same application as you are running it less hard and also spending less money on electricity doing so (26%).
There are similar numbers for the CDXL-30 over the CXL-30 (those I have not tested yet).
The CDXL-45 is another animal all together. The performance gain on that lamp is 38%!!! That is huge. That is the difference between 11.6fL and 16fL...just by changing the lamp!
This is a lamp I have been doing some extensive testing on. It looks to be a VERY stable lamp with a lower than normal burn-back and an even slower than normal decay. Thus it is brighter and more stable that most any alternative it is wattage range.
Now look at the CDXL-60. It is listed as only a 11% gain. So, if you had 14fL...it will only bring you up to 15.54fL. Some might not see that as such a big deal for the extra expense.
Another thing to consider is that as the arc gets larger on the larger lamps, the actual light efficientcy goes down as the aperture (or imager) puts restrictions on efficientcy. Thus a 6KW lamp generally does not bring that much more light than a 4KW lamp in a 35mm application though it is likey to improve a 70mm application. The same would hold true for DLP imagers...though I don't know of any of the .98" DLPs that will support a 6KW...most likely for this reason (not to mention they are typically smaller machines and would need more venting).
As for lamps in general....you should always have at least 30% more power available to you when the lamp is new if you expect to have the light remain good over a reasonable period of time...if you are starting at 90% of rated power...you will likey not have good light for too long....film or digital.
It sounds to me like you need to go to 3KW in your 2KW applications and 4.5KW in your 3KW applications. While the lamps may cost more at the onset...you will likely have well-lit pictures for much longer...which might end up being less costly as the $$/hour of lamp life will actually be less.
Steve
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David Zylstra
Master Film Handler
Posts: 432
From: Novi, MI, USA
Registered: Mar 2007
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posted 06-13-2008 10:22 PM
Here is "as advertised": A CDXL-20 can be used instead of a CXL-30 A CDXL-30 can be used instead of a CXL-45 A CDXL-45 can be used instead of a CXL-60
I am testing the above for validity.
The screen in question with the CDXL-20 normally uses a CXL-30 and that lamp can maintain near 14FL over it's life, BUT the CDXL-20 cannot. Also, by my calculation the CDXL-30 after only 1,000 hours cannot even properly light the screen that currently has the CDXL-20.
Here is the estimated lumen output of each lamp type in the CP2000H: CXL-30 - 8500 CDXL-20 - 9000 CXL-45 - 12,000 CDXL-30 - 13,600 CXL-60 - 18,000 CDXL-45 - 18,700 CDXL-60 - 20,000
So from the above estimations the CDXL lamps **should** be able to replace the next higher CXL lamp size.
I was told that because of the .98" chip's heat limitation the largest lamp possible is a 2kw - hence the CDXL-20SD that is supposed to output 12,000 lumens with the M projector.
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