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» Film-Tech Forum   » Operations   » Digital Cinema Forum   » Pre-Show Projector Bulb Life (Page 1)

 
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Author Topic: Pre-Show Projector Bulb Life
Josh Rosen
Film Handler

Posts: 49
From: Toronto, Ontario, Canda
Registered: May 2007


 - posted 08-23-2007 10:43 AM      Profile for Josh Rosen     Send New Private Message       Edit/Delete Post 
Lately I have been noticing that many of the bulbs in our pre-show projectors (Christie LW-25's) are getting dark and need replacement well before they reach the 1000 hour mark at which point they are supposed to be replaced. The other day i had to replace one that only had 387 hours on it (the others had about 800 hours) because the image was so dark, it was barley visible and yet on other projectors I have bulbs that are over the 1000 hours and still look as good as the day I installed them.

Every time I pull out one of these bulbs that go dark early I notice the same thing. The actual bulb inside of the reflector, is no longer straight, it is bent on an angle so it is no longer properly aligned with the reflector. I also notice that there is usually a large wad of what looks like glue inside of the reflector at the base of the bulb where it meets the reflector. It looks almost like this glue has "bubbled up" and pushed the bulb off on an angle.

Does anyone know what could be causing all these early bulb failures? Any suggestions on how to fix this problem?

Here are some pics I shot of the most recent defective bulb, I know they are a little hard to make out.

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Stephen Furley
Film God

Posts: 3059
From: Coulsdon, Croydon, England
Registered: May 2002


 - posted 08-23-2007 10:50 AM      Profile for Stephen Furley   Email Stephen Furley   Send New Private Message       Edit/Delete Post 
Could it be overheating; clogged air filters?

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David Zylstra
Master Film Handler

Posts: 432
From: Novi, MI, USA
Registered: Mar 2007


 - posted 08-23-2007 10:52 AM      Profile for David Zylstra   Email David Zylstra   Send New Private Message       Edit/Delete Post 
Just a thought - are you being sent recycled lamps? (there are a few companies that will replace the lamp portion of video projector lamp assemblies at a slightly lower cost than a new assembly).

I recently had some Infocus lamps that seemed to be dimmer than previous replacements and it looked like the ones received were off brand replacements and not actual Infocus brand (I didn't do the replacements myself so I don't know if they showed the same issue as yours).

Just some thoughts to help track down the cause . . . . . .

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Gordon McLeod
Film God

Posts: 9512
From: Toronto Ontario Canada
Registered: Jun 99


 - posted 08-23-2007 11:01 AM      Profile for Gordon McLeod   Email Gordon McLeod   Send New Private Message       Edit/Delete Post 
I have yet to have any Metal Halide type video lamp get close to its rated life before it either starts to flicker or gets odd colour shadows in the image

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Josh Rosen
Film Handler

Posts: 49
From: Toronto, Ontario, Canda
Registered: May 2007


 - posted 08-23-2007 11:14 AM      Profile for Josh Rosen     Send New Private Message       Edit/Delete Post 
quote: Stephen Furley
Could it be overheating; clogged air filters?
I regularly clean the air filters and replace them every time I change a bulb so I don't think this is the cause although this thought occurred to me as well. Also we have never had the "temp warning" light go on on the projectors. They are only on for around 25 minute intervals before each show.

quote: David Zylstra
Just a thought - are you being sent recycled lamps? (there are a few companies that will replace the lamp portion of video projector lamp assemblies at a slightly lower cost than a new assembly).
Interesting thought, but nothing has ever led me to believe that these are refurbished lamps. We order from Christie and I always receive the proper documentation from Christie with each lamp i.e. warranty claim forms (which I have been making great use of [Smile] ), safety docs... Is there any way I can check to make sure that they are not refurbished?

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Stephen Furley
Film God

Posts: 3059
From: Coulsdon, Croydon, England
Registered: May 2002


 - posted 08-23-2007 11:39 AM      Profile for Stephen Furley   Email Stephen Furley   Send New Private Message       Edit/Delete Post 
It's difficult to be sure from those pictures, but those lamps look more like UHP mercury rather than metal halide. If that is the case then the reflectors will have been designed for the very small arcs in these lamps. and alignment of the arc tube with the reflector will be critical.

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Josh Rosen
Film Handler

Posts: 49
From: Toronto, Ontario, Canda
Registered: May 2007


 - posted 08-23-2007 11:44 AM      Profile for Josh Rosen     Send New Private Message       Edit/Delete Post 
Yes I believe they are UHP Mercury. I inspect each one before the install and they are always properly aligned initially. when they darken prematurely I always notice the bulb is misaligned with the reflector when I pull it out.

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Cody Martin
Expert Film Handler

Posts: 214
From: Edinburgh, IN, USA
Registered: Jun 2004


 - posted 08-23-2007 11:49 AM      Profile for Cody Martin   Author's Homepage   Email Cody Martin   Send New Private Message       Edit/Delete Post 
I'm not familiar with that digital projector, but we had a similar proplem with one. Check to make sure the cooling fan is staying on after the projector kicks off.

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David Zylstra
Master Film Handler

Posts: 432
From: Novi, MI, USA
Registered: Mar 2007


 - posted 08-23-2007 12:21 PM      Profile for David Zylstra   Email David Zylstra   Send New Private Message       Edit/Delete Post 
quote: Josh Rosen
Interesting thought, but nothing has ever led me to believe that these are refurbished lamps. We order from Christie and I always receive the proper documentation from Christie with each lamp i.e. warranty claim forms (which I have been making great use of ), safety docs... Is there any way I can check to make sure that they are not refurbished?
If they are coming directly from Christie then I'd be confident they are new, a third party off-brand compatible replacement would be suspect - recycled lamps should be marked somehow . . . . . . maybe Christie had a run of bad lamps . . . . . make sure you alert the dealer you order through so they can follow up with other clients who may have the same issue and prove if this is a lamp issue . . . . .

Have any subsequent lamps lasted longer than these "bad" lamps? i.e. after you change them out did the replacement last longer.

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Josh Rosen
Film Handler

Posts: 49
From: Toronto, Ontario, Canda
Registered: May 2007


 - posted 08-23-2007 12:37 PM      Profile for Josh Rosen     Send New Private Message       Edit/Delete Post 
Sometimes the replacements last longer (although nothing has come near that 800 hour mark really since we only use them about 2 hours per day). I haven't had any of the new ones fail yet but the replacements have been from multiple shipments and orders.

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Darryl Spicer
Film God

Posts: 3250
From: Lexington, KY, USA
Registered: Dec 2000


 - posted 08-23-2007 12:44 PM      Profile for Darryl Spicer     Send New Private Message       Edit/Delete Post 
Supposedly the Christie warranty life on these bulbs is 500 hours. It's gotten to the point where our company is using a bulb refurbishing company to replace the lamps to help save on costs. All we have to do is send the spent bulbs back to them. One thing that I think is a problem with these projectors is that I do not think they get the proper cool down process when the projector is turned off at the start of the feature. I think that is causing the bulbs to weaken over time and that is why the bulb element starts to droop.

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David Zylstra
Master Film Handler

Posts: 432
From: Novi, MI, USA
Registered: Mar 2007


 - posted 08-23-2007 12:54 PM      Profile for David Zylstra   Email David Zylstra   Send New Private Message       Edit/Delete Post 
Good point, if the projector gets the power cut to turn it off then that is definitely a factor . . . . . hopefully they are set up with a controller that turns the projector off properly with the right cool down.

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Thomas Pitt
Master Film Handler

Posts: 266
From: Leeds, West Yorkshire, UK
Registered: May 2007


 - posted 08-23-2007 01:41 PM      Profile for Thomas Pitt   Email Thomas Pitt   Send New Private Message       Edit/Delete Post 
Most digital video projectors have an in-built circuit that keeps the fan going for a while after you press the power button, only turning it off after a time delay or when a temperature sensor triggers it. Would it be possible to somehow set up the automation so that it presses the 'standby' button on the projector, instead of just cutting power?

Perhaps it would just be better to wire up the fan to a separate power supply, and have it running all the time (even during the show when the projector is off)?

Alternatively, use old-fashioned 35mm slide projectors - most cinemas in the UK still do that! At least the bulbs for those aren't as expensive [Wink]

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David Zylstra
Master Film Handler

Posts: 432
From: Novi, MI, USA
Registered: Mar 2007


 - posted 08-23-2007 03:13 PM      Profile for David Zylstra   Email David Zylstra   Send New Private Message       Edit/Delete Post 
I think most professional installs of video preshow projectors do have a controller that puts it into standby when the show starts, anyone not using one is asking for trouble.

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Bruce Hansen
Jedi Master Film Handler

Posts: 847
From: Stone Mountain, GA, USA
Registered: Dec 1999


 - posted 08-23-2007 06:16 PM      Profile for Bruce Hansen   Email Bruce Hansen   Send New Private Message       Edit/Delete Post 
Make sure that the contacts on the lamp and the socket are clean, and tight. Dirty or lose contacts will cause extra heat.

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