Film-Tech Forum ARCHIVE: Switching off Video projector for short breaks?

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Posted by John Koutsoumis (Member # 1855) on 10-23-2005, 08:15 AM:

Along side 35 & 16MM we run video as well. We hire the theatre out and on most occasions it's video that's used
(a Dreamvision dlp 500).
Most times between bookings or intermissions there night be 30-40 minutes break. Is it worth switching the lamp off or leaving it on. The reason i'm asking is, how much lamp life do you loose everytime you strike it, is it similar to large xenons? We are on a tight budget and need to get as much life out of the lamp before it becomes unacceptable.

Posted by Richard May (Member # 2627) on 10-23-2005, 10:36 AM:

John, we have been running video for over 5 years. I compared the difference between leaving them on and shutting them off in between shows. Over about 3 years of doing that there was about about a 20% reduction of life on the bulbs when we relit them after the intermissions. We leave them on all day now.

Posted by John Koutsoumis (Member # 1855) on 10-23-2005, 11:29 PM:

Thanks Richard. I thought that would be the case. For the most part i've left it on but sometimes at the insistance of the boss, i'd turn it off.

Posted by Randy Stankey (Member # 64) on 10-25-2005, 10:02 AM:

I have always gone by the theory that one strike of a lamp is equal to two or three hours of running time. Therefore, if you're going to strike a lamp you might as well leave it burn.

I'd rather see a lamp struck once and left on all day than to have it struck up and shut off ten times.

Provided you have proper ventillation and temperature control, just shut the dowser or, in the case of a video projector, set it for "No-Show".

Posted by Brad Miller (Member # 2) on 10-25-2005, 02:37 PM:

I used to go by that theory, but after doing some comparisons of my own with Sanyo low-end LCD projectors for preshow material, I found it was indeed better to turn the things off once the movie started. I don't blame the shortened lamp life so much on the striking of the bulb as I do the constantly running fans that would clog up the air filters and cause the unit to overheat.

I get better life now by having the automation shut them off during the movie. [Wink]

Posted by Randy Stankey (Member # 64) on 10-26-2005, 07:58 PM:

So, sending somebody around to make sure the air vents aren't dusty wouldn't be an option?

[Wink]

Posted by Brad Miller (Member # 2) on 10-26-2005, 09:29 PM:

You do that anyway, but it severely decreases how often they have to be cleaned.

Posted by Richard May (Member # 2627) on 10-26-2005, 09:31 PM:

You are both right. The vents would and do get clogged over time. As Randy said though, someone should be sent around to clean them. I clean them once a week. I would not turn them off just for that reason, though. If people can't go around and clean the vents, they should not be using the equipment. Unfortunately, it happens all the time. [thumbsup]

Posted by Phil Blake (Member # 2012) on 10-27-2005, 09:37 AM:

We have some interesting facts here . I was recently curious as to the life of LCD projecot globes. We are running a midrange panasonic for screen advertising , it runs for about 5 minutes 4 to 6 times a day all week, automatically turning off with the automation. The manual states lamp life should be about 1200 hours , air filters always cleaned and vents free of dirt build up I just got 250 hours out of the globe before it exploded. My immediate thoughts were the turning on and off all the time. The glode cost $800 AU !!! very costly I thought.

Posted by Mark Hajducki (Member # 1732) on 10-27-2005, 09:58 AM:

quote: Phil Blake
automatically turning off with the automation.

Is the automation disconecting the power to the projector or sending a 'turn off' instruction (to allow the bulb to cool properly?)

Many video projectors have power saving modes (where the bulb brightness is reduced along with the fan speed). For short gaps this may be a better option than a complete shutdown.

Is it worth running video (or slide) adverts for 5 minutes between shows?

Posted by Richard May (Member # 2627) on 10-27-2005, 10:46 AM:

Mark, good point about shutting off the power. Most projectors keep the fan running for 5 or 10 minutes after you turn them off to cool the bulb more. Phil, check your manual also to see whether or not it's okay to have the bulb on for that short a period of time. My book says to have it lit for at least 10 minutes before turning it off. We keep them on all day (11 hours) and get on average 1500-2000 hours out of them. [thumbsup]

Posted by Jeff Taylor (Member # 443) on 10-27-2005, 12:16 PM:

I've read about studies comparing the lifespan of DLP's to LCD's which supposedly produced problems with color "burn out" on LCD's left on continuously for really extended periods. I believe it was with blue chip fade or burnout specifically (I won't make the obvious comparison to pre-LPP Eastman prints!) and if I recall supposedly happened as early as 2,000 hours. Has anybody run into that, or is it propaganda from the DLP crowd?

Posted by Richard May (Member # 2627) on 10-27-2005, 12:23 PM:

2 of our LCD projectors are more than 5 years old. No color problems so far.

Posted by Brad Miller (Member # 2) on 10-27-2005, 12:37 PM:

Mark, a video projector should never simply have it's power cut in the manner that most people handled their slide projectors. You must think I'm some kind of idiot if that's how you thought I wired them up to the automations.

I also went into the service menu of my projectors and extended the cooldown time to 15 minutes and set it so the fan runs at 100% speed. I got much better life from doing that over the default settings.

Jeff, yes LCD projectors look crappy as time passes. Since it is a gradual thing, most people don't really notice though, but all LCD machines do suffer picture quality the older they get.

Posted by Phil Blake (Member # 2012) on 10-27-2005, 10:39 PM:

The automation is switching the unit to standby mode leaving the cooling fans operational.

Posted by John Koutsoumis (Member # 1855) on 10-27-2005, 11:11 PM:

Over the two years I've been at the this Theatre I'm at now I have not noticed any decrease in brightness of the lamp. We don't use it everyday but when we do it could amount to 3-5 hours. The last time we had it serviced we were told that the lamp is in good shape.
He also mentioned that the Dream Visions models have a rugged design because they were made for use by the military??

I suppose pre-show stuff is not that much of a big deal but when you have picky directors and produces bringing in their work to showcase to an audience the projector is highly scrutinized.

Never had complaints except for when someone brought in a badly authored DVD, in which I proved it was the DVD at fault and not the projector.