Film-Tech Cinema Systems
Film-Tech Forum


Post New Topic  Post A Reply
my profile | my password | register | search | faq & rules | forum home
  next oldest topic   next newest topic
» Film-Tech Forum   » Operations   » Large Format Forum   » XENON 7K lamp alignment problems

   
Author Topic: XENON 7K lamp alignment problems
Ivan Plamondon
Film Handler

Posts: 42
From: Welland, Ontario, Canada
Registered: May 2013


 - posted 08-09-2013 05:18 PM      Profile for Ivan Plamondon   Email Ivan Plamondon   Send New Private Message       Edit/Delete Post 
During my last two lamp changes, I have noticed a "hot Spot" located in the lower center of the screen when running the test loop(and viewing our feature film). No amount adjustment to the x, y or z axis can move this hot spot to the center of the screen. I have spoken with our IMAX tech and he says I basically have to live with this current scenario. Does anyone have any suggestions as to why this is happening?

 |  IP: Logged

Richard Hamilton
Phenomenal Film Handler

Posts: 1341
From: Evansville, Indiana
Registered: Jan 2000


 - posted 08-10-2013 06:00 AM      Profile for Richard Hamilton   Email Richard Hamilton   Send New Private Message       Edit/Delete Post 
sounds like your IMAX "tech" is lazy [Roll Eyes]

 |  IP: Logged

Dave Macaulay
Film God

Posts: 2081
From: Toronto, Canada
Registered: Apr 2001


 - posted 08-10-2013 09:43 AM      Profile for Dave Macaulay   Email Dave Macaulay   Send New Private Message       Edit/Delete Post 
What kind of projector though? Is this the Niagara Falls theatre?
I think NF has the Imax "Classic" with a 7kW aircooled lamphouse, as I recall that type has no folding mirror (been a while, I could be mistaken).
Either the reflector is distorted or the reflector optical axis is not coaxial with the lens optical axis. Neither was unusual with the 7kW lamphouse.
I think the reflector had to be cut to fit and the cutting could distort the shape, but it can be checked with a point source light (like a krypton 2AA mini maglight with the front cap off, poked through the reflector hole from the back) - the light pattern projected from the mirror onto a wall contains a bunch of concentric circles which will be round from a good reflector, odd shaped if the shape is distorted.
Alignment of the axes was done with either a string (old school, not very accurate) or with a laser mounted in the reflector hole with its beam on the reflector axis, the mirror is moved so the beam is down the centre of the lens axis (the reflected light pattern from the lens elements then becomes concentric circles, one for each element).

 |  IP: Logged

Ivan Plamondon
Film Handler

Posts: 42
From: Welland, Ontario, Canada
Registered: May 2013


 - posted 08-10-2013 04:34 PM      Profile for Ivan Plamondon   Email Ivan Plamondon   Send New Private Message       Edit/Delete Post 
I'm hoping it gets resolved at my next service this month. It's been a challenge finding a midway point between reducing the "hot spot's" brightness by pulling back on the "Z" axis vs keeping the overall image as bright as possible by increasing the rectifier's power.We currently try to hover around 155 amps and 32 DC volts in order to attain longevity with our lamp (700 + hours). The last few weeks of the lamp life, the amps usually drop to around 150. I'm the "new kid on the block" here so I'm trying to get as much knowledge as possible. Thanks everyone for your input on this matter.

 |  IP: Logged

Gordon McLeod
Film God

Posts: 9443
From: Toronto Ontario Canada
Registered: Jun 99


 - posted 08-17-2013 03:03 PM      Profile for Gordon McLeod   Email Gordon McLeod   Send New Private Message       Edit/Delete Post 
Pyramid Place Imax remember it well
It had a classic aircooled machine the reflector came from ORC if memory serves

 |  IP: Logged

Ivan Plamondon
Film Handler

Posts: 42
From: Welland, Ontario, Canada
Registered: May 2013


 - posted 08-17-2013 07:43 PM      Profile for Ivan Plamondon   Email Ivan Plamondon   Send New Private Message       Edit/Delete Post 
Can't wait for our next service call. Laser alignment is in the works!

 |  IP: Logged

Ivan Plamondon
Film Handler

Posts: 42
From: Welland, Ontario, Canada
Registered: May 2013


 - posted 08-26-2013 09:15 PM      Profile for Ivan Plamondon   Email Ivan Plamondon   Send New Private Message       Edit/Delete Post 
Turns out the mirrors were out of alignment. Balance has been restored thanks to our service tech.

 |  IP: Logged



All times are Central (GMT -6:00)  
Post New Topic  Post A Reply Close Topic    Move Topic    Delete Topic    next oldest topic   next newest topic
 - Printer-friendly view of this topic
Hop To:



Powered by Infopop Corporation
UBB.classicTM 6.3.1.2

The Film-Tech Forums are designed for various members related to the cinema industry to express their opinions, viewpoints and testimonials on various products, services and events based upon speculation, personal knowledge and factual information through use, therefore all views represented here allow no liability upon the publishers of this web site and the owners of said views assume no liability for any ill will resulting from these postings. The posts made here are for educational as well as entertainment purposes and as such anyone viewing this portion of the website must accept these views as statements of the author of that opinion and agrees to release the authors from any and all liability.

© 1999-2018 Film-Tech Cinema Systems, LLC. All rights reserved.