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» Film-Tech Forum   » Operations   » Film Handlers' Forum   » Leave xenon lamp on or off between changeovers?

   
Author Topic: Leave xenon lamp on or off between changeovers?
Gary A. Hoselton
Film Handler

Posts: 42
From: Portland OR U.S.A.
Registered: Nov 2005


 - posted 08-25-2017 12:45 PM      Profile for Gary A. Hoselton   Email Gary A. Hoselton   Send New Private Message       Edit/Delete Post 
I'm running 2000W lamps in Strong Super LUME-X lamphouses. I'm in habit of turning lamp off in outgoing projector after changeover, as seems waste of electricity to keep it on. Another fellow keeps both lamps on for length of program. I'm guessing it is a function of lamp strikes vs. lamp life. What is the professional opinion?

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Jerry Axelsson
Film Handler

Posts: 87
From: Stockholm, Sweden
Registered: May 2005


 - posted 08-25-2017 01:02 PM      Profile for Jerry Axelsson   Email Jerry Axelsson   Send New Private Message       Edit/Delete Post 
Hello Gary,

I suggest to leave them on. The number of strikes has killed them premature for me otherwise. Focus more on having good cooling of the lamp-house and good rectifiers. This will increase the life of the bulb quite far beyond warranty-hours.

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Jack Ondracek
Film God

Posts: 2269
From: Port Orchard, WA, USA
Registered: Oct 2002


 - posted 08-25-2017 05:30 PM      Profile for Jack Ondracek   Author's Homepage   Email Jack Ondracek   Send New Private Message       Edit/Delete Post 
I occasionally run a similar setup at a Seattle non-profit. We leave the lamps on throughout the show... same reasoning as Jerry says.

Some years ago, we had a screening room in Seattle with a changeover booth. They also left their lamps on.

One other point... Once you strike them, you generally can have confidence they'll run until you turn them off. It would be unfortunate to get to reel 4 and have an igniter or power supply diode fail on you.

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Scott Norwood
Film God

Posts: 7907
From: Boston, MA. USA (1774.21 miles northeast of Dallas)
Registered: Jun 99


 - posted 08-25-2017 06:09 PM      Profile for Scott Norwood   Author's Homepage   Email Scott Norwood   Send New Private Message       Edit/Delete Post 
Agreed with everything that Jack said. You don't want to lose an igniter mid-show. Most lamps also take a few minutes to get up to full brightness (you can test this with a light meter), so you would want to strike them a few minutes before the changeover, anyway.

Also, some sound systems make a slight buzz when the lamp strikes, and it is generally preferable not to have this happen mid-show. (Obviously, the best solution is to fix that problem.)

Some Kinoton projectors switch the lamps with the motors, so there isn't much choice there, especially if you have Kinotons without hand dousers.

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Mark Gulbrandsen
Resident Trollmaster

Posts: 15991
From: Bountiful, Utah
Registered: Jun 99


 - posted 08-25-2017 08:55 PM      Profile for Mark Gulbrandsen   Email Mark Gulbrandsen   Send New Private Message       Edit/Delete Post 
Every time you strike a lamp there is a large amount of inrush current that travels through the lamp. It's typically three to six times the operating current of the lamp and only lasts for a fraction of a second. But it's this inrush that kills the lamps prematurely. Best to leave it on for the duration of the show.

Mark

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Jim Cassedy
Phenomenal Film Handler

Posts: 1519
From: San Francisco, CA
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 - posted 08-25-2017 10:03 PM      Profile for Jim Cassedy   Email Jim Cassedy   Send New Private Message       Edit/Delete Post 
^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^
Agree with all the comments above, and in addition I'd add that leaving them
on puts the bulbs thru less 'thermal cycling' as they heat up & cool down multiple
times during an evening of shows. I've beem told excessive heating & cooling cycles
can weaken seals or the bulb envelope, especially if there are any flaws or weak
spots in them. The one concession I make is that I turn the blub off in one projector
at the end of the night while the last reel is running in the other one.

One of the private preview theatres I work at has a pair of Kinotons like what Scott
mentioned in which the bulbs go on & off automatically with the motors in each projector.

> Anybody know if this can be disabled?<

(Obviously I could completely re-wire things. I'm just wondering if there was an 'easy
way' to re-cofigure settings inside the projector or something like that)

If it were up to me, I'd still be running carbon arcs.

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Steve Kraus
Film God

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From: Chicago, IL, USA
Registered: May 2000


 - posted 08-25-2017 11:38 PM      Profile for Steve Kraus     Send New Private Message       Edit/Delete Post 
I left them on between screenings, too. The downtime would need to be over a half hour approaching an hour to shut down. Same thing with the DC projector.

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Jerry Axelsson
Film Handler

Posts: 87
From: Stockholm, Sweden
Registered: May 2005


 - posted 08-26-2017 02:25 AM      Profile for Jerry Axelsson   Email Jerry Axelsson   Send New Private Message       Edit/Delete Post 
I manage a cinema which is a Kinoton booth.
All cinemas are change-over houses since we are an archival institution.

We have swapped the switch on the lamphouse and solved the problem with the lamp only running when the motor is active.
Now, we have a switch with three positions.
Middle position - OFF
Upwards -Lamp on with cooling fans on.
Downwards - Lamp off with cooling fans on (for after-cooling when you turn the lamp off) This can also be done with a timer.

You still need some kind of dowser to protect the shutter when the machine is standing still.

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Randy Stankey
Film God

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From: Erie, Pennsylvania
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 - posted 08-26-2017 08:37 AM      Profile for Randy Stankey   Email Randy Stankey   Send New Private Message       Edit/Delete Post 
At my last job, we used to go by the rule: One strike is equal to an hour of burn time.

With shows starting at the top of every hour, we would strike up the lamp (6 KW) at the beginning of the day and let it burn all day, from 10 a.m. until 6 p.m.

We would only shut down if there was a no-show where there wasn't any tickets sold.

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Paul Mayer
Oh get out of it Melvin, before it pulls you under!

Posts: 3835
From: Albuquerque, NM
Registered: Feb 2000


 - posted 08-26-2017 12:22 PM      Profile for Paul Mayer   Author's Homepage   Email Paul Mayer   Send New Private Message       Edit/Delete Post 
Same with us at the old Caesars Palace Omnimax - shows every hour on the hour, typically 35-45 minutes on each show. We lit the lamp a few minutes before first show then left it lit for the day. It was nice that the 15kW lamp was designed to run at half-power between shows, which helped keep operating temperatures more even (don't try the half-power thing if the lamp isn't designed for it though).

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Gary A. Hoselton
Film Handler

Posts: 42
From: Portland OR U.S.A.
Registered: Nov 2005


 - posted 08-26-2017 01:24 PM      Profile for Gary A. Hoselton   Email Gary A. Hoselton   Send New Private Message       Edit/Delete Post 
Thanks much for background and reasoning. Henceforth, once I switch a lamp on, I shall leave it on for duration of screening (hoping to remember to open lamphouse douser before starting projector motor). Projectors are Simplex XL, controlled by rocker switches on TA-10's.

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Mike Blakesley
Film God

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From: Forsyth, Montana
Registered: Jun 99


 - posted 08-26-2017 02:23 PM      Profile for Mike Blakesley   Author's Homepage   Email Mike Blakesley   Send New Private Message       Edit/Delete Post 
I was always told (and have seen in other threads here) that if the bulb can be off for 10 minutes or more, then shut it off. Otherwise leave it on.

I figure, we aren't running it past warranty anyway so if it craps out after a 12-minute shutdown with only 300 hours on it, we're getting a new bulb.

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Gordon McLeod
Film God

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From: Toronto Ontario Canada
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 - posted 08-26-2017 02:35 PM      Profile for Gordon McLeod   Email Gordon McLeod   Send New Private Message       Edit/Delete Post 
I always liked the Xebex system of lamps going to standby power when the dowser closed
Imax had the standby mode as well

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Jim Cassedy
Phenomenal Film Handler

Posts: 1519
From: San Francisco, CA
Registered: Dec 2006


 - posted 08-26-2017 02:45 PM      Profile for Jim Cassedy   Email Jim Cassedy   Send New Private Message       Edit/Delete Post 
quote: Jerry Axelsson
We have swapped the switch on the lamphouse and solved the problem
Thanks Jerry. I had a feeling it was a bit more involved than just
re-setting some DIP switches or changing a jumper inside the proj.

I'm leaving town (again) for awhile to work at another film fest,
so maybe when I'll tackle this project when I get back, since it's
something I've wanted to do for a while.

(and 'yes' - these Kinotons have both manual & electric dowsers
on them, so that's not a concern I have to deal with )

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Jerry Axelsson
Film Handler

Posts: 87
From: Stockholm, Sweden
Registered: May 2005


 - posted 08-27-2017 04:45 AM      Profile for Jerry Axelsson   Email Jerry Axelsson   Send New Private Message       Edit/Delete Post 
Jim, if you would like to know what we have done to our Kinotons send me a PM when you are back.

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