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» Film-Tech Forum   » Operations   » Digital Cinema Forum   » When to swap a bulb? (Page 1)

 
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Author Topic: When to swap a bulb?
Andrew Thomas
Master Film Handler

Posts: 264
From: Pearland, TX, USA
Registered: Jun 2012


 - posted 01-30-2015 01:18 PM      Profile for Andrew Thomas   Email Andrew Thomas   Send New Private Message       Edit/Delete Post 
I have 4 Christie series 2 projectors (1 CP4220, and 3 Solaria Ones).

We get 14+ FTL on screen with new bulbs at the lowest output setting, and still get 14 FTL at about 80%. The bulbs are past their rated hours (at about 3000 on CDXL30, and 3800 on the CDXL-16Ms) but I haven't even had any issue with any of the lamps failing to strike (except at about 1500 hours on on the Solaria Ones after a bad software update) and as I said, the image is still plenty bright.

So do you do changes at specific hours, light levels, when errors start?

Thanks.

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Gavin Lewarne
Master Film Handler

Posts: 278
From: Plymouth, UK
Registered: Aug 2009


 - posted 01-30-2015 02:37 PM      Profile for Gavin Lewarne   Email Gavin Lewarne   Send New Private Message       Edit/Delete Post 
I change lamps no later than 100-hours-to-warranty, which for us happens to always be every year.

I would never, ever, take any lamp in a digital projector past its warranty hours. Doing so, is frankly, stupid.

Not sure what the exact lamps you have are but those hours are way beyond any warranties hours for any lamps I know and I would change them PRONTO

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Marco Giustini
Film God

Posts: 2534
From: Reading, UK
Registered: Nov 2007


 - posted 01-30-2015 05:48 PM      Profile for Marco Giustini   Email Marco Giustini   Send New Private Message       Edit/Delete Post 
It's a matter of math.
If a lamp exploded in a Christie then you have to replace the whole reflector - and you lose shows.

I heard a reflector is about 4 grand. Plus engineer and loss of revenue.

Is that worth the savings on the lamps? Your call.

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Stephan Shelley
Jedi Master Film Handler

Posts: 600
From: castro valley, CA, usa
Registered: Nov 2014


 - posted 01-30-2015 07:40 PM      Profile for Stephan Shelley   Email Stephan Shelley   Send New Private Message       Edit/Delete Post 
In addition to the two parts of the reflector the UV filter will be shattered as well. If you are very unlucky on the 4220 you could nick the integrater rod or the cold mirror on the solaria ones. none of this stuff is cheap.

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Andrew Thomas
Master Film Handler

Posts: 264
From: Pearland, TX, USA
Registered: Jun 2012


 - posted 01-30-2015 08:01 PM      Profile for Andrew Thomas   Email Andrew Thomas   Send New Private Message       Edit/Delete Post 
None of this has been a cost question, I just have no idea and we are still on the original bulbs that were installed when we opened 13 months ago.

So you guys typically change at around the warranty hours? Is there a particular reason for that as opposed to the average hours listed on the Christie bulb pages?

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Stephan Shelley
Jedi Master Film Handler

Posts: 600
From: castro valley, CA, usa
Registered: Nov 2014


 - posted 01-30-2015 08:10 PM      Profile for Stephan Shelley   Email Stephan Shelley   Send New Private Message       Edit/Delete Post 
If the bulb explodes during the warranty hours the bulb manufacture covers the cost of the damage as well as the bulb.

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Buck Wilson
Jedi Master Film Handler

Posts: 843
From: St. Joseph MO, USA
Registered: Sep 2010


 - posted 01-30-2015 08:11 PM      Profile for Buck Wilson   Email Buck Wilson   Send New Private Message       Edit/Delete Post 
If a bulb blows within warranted hours, the bulb manufacturer will cover the cost of any damage done to the projector.

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Justin Hamaker
Film God

Posts: 2044
From: Lakeport, CA USA
Registered: Jan 2004


 - posted 01-30-2015 08:14 PM      Profile for Justin Hamaker   Author's Homepage   Email Justin Hamaker   Send New Private Message       Edit/Delete Post 
With regard to the bulb its self, the question is whether you are in warranty on you projector and whether the bulb is still performing as expected.

If your projector is still in warranty, then you should never run a bulb past the rated life. This can void warranties. If the projector is beyond warranty, then it's a cost/benefit decision as long as the bulb output is still bright and stable. In this case it just comes down to whether the savings from running a bulb past warranty is worth the potential cost of replacing parts in your projector, and the associated down time.

If a bulb is lasting you a full year, that means you are running a fairly limited schedule. My theatre runs a minimum schedule during the school year, but the rated life on a bulb still only gets us about six months. The cost of a bulb once a year is probably far less than any projected equipment replacement costs. Plus the savings of squeezing an extra 6 months from a bulb is minimal.

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Andrew Thomas
Master Film Handler

Posts: 264
From: Pearland, TX, USA
Registered: Jun 2012


 - posted 01-30-2015 08:59 PM      Profile for Andrew Thomas   Email Andrew Thomas   Send New Private Message       Edit/Delete Post 
Thanks for the wise council! We will be swapping all the bulbs in the next week anyway, but we will move to a replacement policy at the warranty hours. Again, cost doesn't make much difference to me...as has been mentioned, the difference is pretty minimal anyway.

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Ram Melegrito
Film Handler

Posts: 12
From: Mandaluyong City, Philippines
Registered: Dec 2014


 - posted 01-31-2015 01:04 AM      Profile for Ram Melegrito   Email Ram Melegrito   Send New Private Message       Edit/Delete Post 
Our supplier is giving us a warranty for our bulbs of 1,000 hours. We have about ten hours worth of shows everyday; we replace the bulbs every three months.

Is the 1,000-hour limit correct? There are only two suppliers for all cinema projection equipment here in the Philippines, and one is exclusive to one of the major local chains. I feel as if they're setting a 1,000 limit so that we order more often, given the lack of choices for suppliers.

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Leo Enticknap
Film God

Posts: 6798
From: Loma Linda, CA
Registered: Jul 2000


 - posted 01-31-2015 01:30 AM      Profile for Leo Enticknap   Author's Homepage   Email Leo Enticknap   Send New Private Message       Edit/Delete Post 
quote: Ram Melegrito
Is the 1,000-hour limit correct?
Depends on the manufacturer and how big the bulb is. Across our two sites we use three types of bulb in total: a 3kW which the manufacturer warranties to 1,200 hours; a 6kW to 600 and a 7kW to 500.

Before I started to work with digital projectors, the general operating practice in pretty much every theater I worked in was to try to run bulbs to at least double the warrantied hours. For example, at one place we ran 1.6kW bulbs in most of the projectors. The warranties were for 1,500 hours, but with quarter-turn rotations every 500 hours and regular checks to ensure that airflow wasn't degraded (e.g. as the result of clogged intakes or failed fans), it was very unusual not to get 3,000 hours (ish) out of them before they started to flicker. It was when they started to flicker and the flicker couldn't be eliminated by rotating them that we tended to replace them.

No-one who supervised me, who I worked with or later, who I supervised believed the risk of explosion to be significant. Techs with decades of experience assured me that the spontaneous explosion of a xenon bulb while burning simply hadn't happened since the 1970s (except for a once-in-a-blue-moon freak event), thanks to improvements in the manufacturing process. Therefore, running the bulbs way past warranty hours was considered a risk worth taking, and we took it. I have only ever witnessed one bulb blow up while lit, and that was as the result of a very damp atmosphere and something like 90% humidity air being sucked into the lamphouse (the theater in question was in its first day of reopening after a huge flood).

In the digital world, however, comments such as those above represent what I've heard from everyone I've talked to: don't run your bulbs one minute over warranty; the risk isn't worth it. Is this just because the consequences of one exploding are so much greater (the reflector is a lot more expensive to replace in a digital lamphouse and other components, in closer proximity to the bulb than is typically the case in a film projector lamphouse, are also at risk), or are the xenon bulbs designed for digital projection more prone to spontaneous explosion in use when excessively worn than those designed for film lamphouses?

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Carsten Kurz
Film God

Posts: 3569
From: Cologne, NRW, Germany
Registered: Aug 2009


 - posted 01-31-2015 05:14 AM      Profile for Carsten Kurz   Email Carsten Kurz   Send New Private Message       Edit/Delete Post 
The risc of a bulb blowing increases with lamp type and wattage, and operating current. Also, digital bulbs have a different design (smaller etendue for digital projectors), increasing the risc even more. Then the cost for mirror+parts replacement in a digital projector is much higher than for film lamphouses.
We probably all know those places running 1.6kW lamps in their 35mm lamp houses for thousands of hours. These would simply 'never' blow, only become dimmer and dimmer.

- Carsten

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Marco Giustini
Film God

Posts: 2534
From: Reading, UK
Registered: Nov 2007


 - posted 01-31-2015 05:33 AM      Profile for Marco Giustini   Email Marco Giustini   Send New Private Message       Edit/Delete Post 
Carsten,

In my experience most of those 35mm had metal reflector which had the advantage of not shattering if the lamp exploded.
I've seen so many badly damaged metal reflectors in old 35mm. The customer thought it was ok. The light output would pay the consequences of course but that was apparently ok for the average cinema.

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Dave Macaulay
Film God

Posts: 2018
From: Toronto, Canada
Registered: Apr 2001


 - posted 01-31-2015 10:17 AM      Profile for Dave Macaulay   Email Dave Macaulay   Send New Private Message       Edit/Delete Post 
Generally, each xenon lamp type from each manufacturer has an hour limit for the replacement warranty, pro-rated for lamp replacement: at 50% life, a failed lamp will be replaced for 50% of the new lamp price. A few lamps actually do have a 1000h warranty, many do not. Smaller wattage tends to be more, higher wattage less. Ushio has extended hour lamps that have over 2000h warranties.
Lamps also have a service life warranty, higher hours than the replacement warranty: if a lamp explodes within it, the ensuing lamphouse damage repair cost is paid by the lamp manufacturer. Past that and, yes, you have to pay for replacement glass mirrors and probably the UV plate: these are not cheap!
Some large chains, maybe some large distributors, buy lamps without warranty - considerably cheaper but they have to pay for early-failure lamp replacement and explosion damage repairs.

I would check on the manufacturers website for the official warranty conditions for your specific lamp.
Something is fishy if your supplier is giving a 1000h warranty on all lamps.

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Leo Enticknap
Film God

Posts: 6798
From: Loma Linda, CA
Registered: Jul 2000


 - posted 01-31-2015 12:08 PM      Profile for Leo Enticknap   Author's Homepage   Email Leo Enticknap   Send New Private Message       Edit/Delete Post 
Thanks Carsten - that was the explanation I suspected and am grateful to have confirmed. Digital bulbs = different design increasing the risk of explosion, plus higher cost of repairing collateral damage.

Yet another example of how the transition to digital has shifted the up-front cost of technical presentation from the studio/distributor to the exhibitor. Assuming that you don't perpetually take, and get away with, the risk of running your bulbs significantly past replacement warranty, then the cost per hour in bulb time for DCP presentation is significantly higher than it is with film (all the other relevant factors being equal).

This is because, as you say, in the film days, you could more or less take the warranty length and double it for what the realistic bulb life actually was, and pretty much everywhere did; but the risk/benefit analysis for a digital bulb comes out against doing that, and so a digital house has to budget more per hour of screen time for xenon bulbs.

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