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Topic: Suggested hours before bulb change

Tom Wienholt
Master Film Handler

Posts: 371
From: Towson, MD, USA
Registered: Dec 2002

posted 11-08-2012 11:11 PM

As a general rule, how many hours should a bulb be used before replacing? I am using Ushio bulbs that are have full warranty up to 3000 hours in nec1200c projectors.

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Dominic Espinosa
Phenomenal Film Handler

Posts: 1172
From: California, U.S.A.
Registered: Jan 2004

posted 11-10-2012 11:08 AM

Much the same as with 35mm you will find some bulbs of identical make and model will last longer than others.
The same rule-of-thumb as with 35mm applies, in my book.
Check the image every couple of weeks for flicker, even and sufficient illumination. If it's in spec, it's good.
Otherwise, yank that sucker.

The biggest factor I've seen in D-Cinema lamps (aside from huge differences between brands) has been how well the lamps are cooled. Nowadays we are told by Ushio to turn the lamps off between shows and we push double the CFM recommended by the manufacturer of the projectors. Our lamps typically last well into 130% of the warranted lifetime before getting pulled.
We base our decision to pull a lamp on a monthly report from the theater where we ask the manager to run the automatic luminanace calibration and then report the lamp power afterward (the projector tweaks the lamp power 'till it hits spec). We may install a 4200w lamp, run the calibration, and see it's running at 53% power, over time it'll work it's way up with every calibration. So if we see it's already past warranty hours and pushing 80% or more lamp power we'll be getting ready to change it.

Obviously, if you want warranty ANYTHING you can't do that. You have to pull it on or before warranty hours are reached. For any damage it causes by blowing up after that is all on you.
And it goes without saying if you have a corporate policy you must follow it.

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