Film-Tech Forum ARCHIVE: Lamp Life in the digital age

This is topic Lamp Life in the digital age in forum Digital Cinema Forum at Film-Tech Forum ARCHIVE.

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Posted by Steve Moore (Member # 4753) on 11-02-2013, 02:43 PM:

I have spent the last half an hour searching the forum, so apologies if this has been brought up before. What are people's views here to lamp life being reduced by an hour per strike these days?

I know when i started 25 years ago and ran twin 35mm with change overs I was taught to leave both lamps running all day, as each strike takes an hour off a lamp's life. I just was pondering this again now with my Christie CP2000s. Our shows (two or three per day) consist of 20 mins of ads and trailers, then a 5 min break to visit the sales stand or our ice cream tray that goes around the auditorium. When I automated my Vic 9s and 8s, we killed the lamp at the interval, as I could not close a lamphouse dowser.

Now in the digital age and basically when the show pauses for the intermission, my macro turns the lamp off; however I wondered if people think I would be better leaving on and just pausing on black, thus saving those theoretical 1 hour reduced off the life for each 5 min break.

What are people's feelings on this?

Posted by Michael Harlow (Member # 1353) on 11-02-2013, 03:32 PM:

Steve,
We were told by our supplier to leave the lamp on, dowser open and project "black" for gaps of upto 30mins, anything over then turn it off.
not sure if that is correct though

Posted by Stefan Vogels (Member # 5573) on 11-02-2013, 03:45 PM:

Lamp manufactures claim that if the intermission is 8 minutes or more you should shut down the lamp.

Posted by Justin Hamaker (Member # 2165) on 11-02-2013, 04:43 PM:

The conventional wisdom is that if your lamp won't be off long enough to completely cool, then it should be left on.

Whether this is true or not, I can't really say. I have never done side by side simulations where lamps are run for 1500 hours with one being left on for 12 hours straight where another is turned off and on every 2 hours. It would be interesting to see a case study as leaving the lamps on means an extra 30-40 minutes of electrical used per auditorium per day.

What I can say is that with a little over 3 years using digital projectors and religiously changing both 3K and 4K bulbs at 1500 hours, I have seen virtually no lamp dimming.

I have changed close to 30 digital bulbs and only one or two have shown any darkening of the glass. The ones that did have any darkening were 4K bulbs that are run at near 100% from hour 1 for 3D shows. Although I would have to go back and check, I believe those were from a period where we have a 3D show virtually 100% of the time in that auditorium.

At 1500 hours, there is also very little sign of wear to the anode or cathode. If not for the warranty hours being exceeded, we could probably continue running these bulbs for another 300-500 hours with no loss in light. This is especially true for the 3K bulbs in our 2D houses.

For what it's worth, have been using the Christie CXL-30SC for our 2D houses, but are switching to the Ushio UXL-30SC starting with the most recent cycle of bulb changes. For our 3D houses we use the Ushio DXL-40SCN.

Posted by John Roddy (Member # 7348) on 11-02-2013, 04:57 PM:

I'm not sure about other manufacturers, but Ushio claims that running their lamps with a ten minute off period between shows makes them last longer. However, I don't like to strike lamps that are still hot, so I'll just leave them on if I can't get that full ten minutes. I haven't seen definitive proof either way of whether or not one's harmful or the other is helpful, but that does seem to be the general logic that everyone follows.

I've been almost exclusively changing every lamp in a 19-screen theater for over 4 years now, and the results I've gotten are all over the place. Some of the old lamps that were run with an off period between shows are burnt to a crisp, while others look like they could easily last for another few hundred hours (I always change lamps at warranty end, regardless). I've also seen some that run all day that start degrading rapidly near the end of their life, and others that could march on way past it. Honestly, the quality of the manufacturing process at the time seems to have way more of an impact than cutting it off between shows. I have noticed that if one lamp manufactured in a certain month starts dying out before its warranty hours end, the rest of the ones I use from that same month seem to do the same. Of course, that could just be a coincidence.

Posted by Peter Castle (Member # 1997) on 11-02-2013, 08:00 PM:

The situation regarding lamp life has really changed since digital. For 35mm, we would run our lamps as long as they produced sufficient brightness. Now we are wary to go past the warranty lifetime for fear of expensive damage if a lamp explodes. Turning off a lamp reduces the hours used, so I'd guess that turning them off for digital is a no-brainer.

On a different but similar topic: do you use the counter on your projector to determine when to change a lamp? If you do, are you aware that the lifetime a projector manufacturer gives a lamp may exceed the warranty time? NEC list four Ushio lamps with lifetimes exceeding Ushio's warranty hours.

So do you use Ushio's warranty or NEC's specified lifetime?

Posted by Ken Lackner (Member # 1002) on 11-04-2013, 08:12 AM:

I would always go with the lamp manufacturer's warranty hours. For NEC, each lamp is set up in the DCC software with current range and warning hours. If a theater is going to start using a different type of lamp, I check these parameters in DCC and correct them if they are wrong. And if the lamp isn't even listed, I just add it.

Posted by Mike Blakesley (Member # 26) on 11-04-2013, 11:16 AM:

I don't think there is anything in the warranty of a bulb that says it must be turned off for any length of time between uses or else the warranty is void. (Is there?)

We use Ushio bulbs and haven't had an explosion happen yet (and used Christie bulbs for the previous 30 years with no explosions ever). We have had one Ushio bulb just stop lighting up after a few hundred hours of use. My friend Gary Dupuis, who works for Polson Theaters, a 22-screen circuit in western Montana running Barco projectors, has had one bulb explode since they went digital in 2011.

Posted by Peter Castle (Member # 1997) on 11-04-2013, 06:23 PM:

Ken, our NEC specifies that the lamp we use (DXL-70SN) has a lifetime of 500 hours. But Ushio only warrants them for 300 hours.
I'm just saying watch what the projector says.

As for turning them off, surely you'll get more uses out of the lamp to warranty life if you are not including non-screening time.

Posted by Justin Hamaker (Member # 2165) on 11-04-2013, 06:48 PM:

Peter, this is just a matter of changing the bulb record in the DCC software. When we started using the Ushio UXL-30SC, there wasn't even an entry for this bulb, so we had to enter it in. Who knows if the person who created the default list even bothered to check on whether the entered warranty hours were correct.

Posted by Steve Guttag (Member # 268) on 11-05-2013, 06:34 AM:

Officially, the UXL-30SC is not a digital lamp, it is a film cinema lamp and is not going to be as efficient as the equivalent wattage digital lamp that was designed for the specific optics in the projector it is designed to go in. Furthermore, the light fall off in film lamps is often over twice as fast as their digital counterparts.

The "SC" lamps are short arcs so one can get away with them. In fact, they can be used in NEC and Barco projectors like the standard CXLs can be used in Christie projectors. One just has to allow for what they can realistically do.

NEC uses a "Certified" lamp system where one enters the certificate number (should be in the box of the certified lamp) and that takes care of putting in the rest of the required data as well as the serial number to be used). All "User" lamps are the higher-number entries. As more certified lamps go on the list, the user lamps keep getting pushed to higher numbers.