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Author Topic: Lamp question Leo Enticknap Film God Posts: 7474 From: Loma Linda, CA Registered: Jul 2000 posted 01-06-2018 11:07 PM                        quote: Jack Ondracek Is the onset of flickering a common problem with digital xenon? Seems that, considering the dramatically shortened warranties these things come with, you barely have time to tint the envelope, much less degrade the anode. I think it's also a culture thing. In the film days, I was encouraged to run bulbs for as long as possible, using regular rotations to maximize their service life. We boasted about squeezing double the warranty hours out of the smaller ones (1.6 and 2kW) before they started to flicker. I suspect that this was because (a) explosions were so rare, especially if the lamphouses were not allowed to overheat, that the risk of running them over hours was considered to be a risk worth taking, and (b) if one did blow, there was still a good chance that it would not write off the reflector. In fact, on the one and only occasion I've witnessed a bulb explode, the reflector wasn't even scratched that we could see. With digital, however, the pressure in the bulb is higher, the reflector is closer to the bulb, it's a lot more expensive to replace, and there is also the risk of taking out other expensive components - cold mirror, triaxial gearbox, etc. etc. So you don't risk it: if the bulb makes it to warranty hours without flickering or losing light output such that you can no longer achieve 14ft-l, then out it comes. The software nag messages and red tail lights also apply subtle psychological pressure not to overrun bulbs, either. I remember pulling one 3kW bulb at the Aero when it started to flicker after around 1,000 hours of a 1,200 hour warranty, but that's the only one. I agree that as a general rule, retiring them at warranty hours means that most digital xenon bulbs are never run for long enough for flickering to become an issue.  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 01-07-2018 08:55 AM                     Remember too, digital projectors use glass reflectors so an explosion almost guarantees that the reflector will be a total loss. With metal reflectors, even if it get dingged up a lot, you can limp along until a replacement comes. This is not the case when a glass reflector shatters. We have a couple of customers that run past warranty. Some have a set percentage (e.g. 25% over warranty) while another goes until a "demonstrated need" like flicker. One thing about digital lamps and their shorter arcs...once they open up enough, they are going to flicker and it will be a pretty rapid transition from stable to flicker.  |  IP: Logged Peter Fagan Film Handler Posts: 17 From: Letterkenny, donegal, Ireland Registered: Aug 2012 posted 01-08-2018 04:59 AM                        If a bulb is starting to flicker on screen i will swap it out as soon as i can.I've been doing this job for 20 years now & the only time a bulb exploded on me was in a digital projector. Like leo said with the 35mm projector you could get double the life from a bulb before you would need to change it out. With digital it is not worth the risk.Granted the bulb that exploded was a faulty bulb so it was covered by warranty from the company.However it did take out the main reflector which i had to wait for a new one to come from Germany which took a few days so i was down a screen for that duration. Normally now once the bulb has reached its warranty hours i just swap it out.tbh its just not worth the cost or the risk to try to squeeze a few more hours out of the bulbs.  |  IP: Logged Monte L Fullmer Film God Posts: 8367 From: Nampa, Idaho, USA Registered: Nov 2004 posted 01-08-2018 08:26 PM                     Course, the trick to bulb longevity is exhaust and lots of it. Get that heat out of the console and the bulbs will like you. Heard why digital projectors has transverse installed bulbs is that the machine can operate at any angle to almost 90 degrees and the bulb remains at a horizontal position. Christie, even though losing one prism in the light stream with their inline bulb installs, can't pitch the machine too much, or the flame touches the envelope of the lamp.  |  IP: Logged Leo Enticknap Film God Posts: 7474 From: Loma Linda, CA Registered: Jul 2000 posted 01-09-2018 07:17 PM                        quote: Monte L. Fullmer Heard why digital projectors has transverse installed bulbs is that the machine can operate at any angle to almost 90 degrees and the bulb remains at a horizontal position. It's also, I guess, why Barco came up with that nightmarish pressurized liquid cooling system for their Series 1 projectors: it works upside down. The Series 2 cooling system, in which coolant is transferred by gravity into the cooling circuit from a reservoir mounted above the light engine, has the advantages of lasting far longer before hoses and quick release couplings have to be replaced, and being much easier to flush and refill; but the projector can only be installed in an upright position.  |  IP: Logged Buck Wilson Jedi Master Film Handler Posts: 894 From: St. Joseph MO, USA Registered: Sep 2010 posted 01-09-2018 07:37 PM                     quote: Peter Fagan the only time a bulb exploded on me was in a digital projector. Same here. We just recently had one explode, a 4k or 4.5k in an NEC NC3200. Crazy the force it must've packed, turned most of the bulb AND reflector to basically sand. A few larger pieces, none larger than the oval portrait on a dollar bill, but the rest just absolutely pulverized. Down house for 3 days.  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 01-09-2018 07:41 PM                     I gotta know...what brand lamp?  |  IP: Logged Leo Enticknap Film God Posts: 7474 From: Loma Linda, CA Registered: Jul 2000 posted 01-09-2018 09:35 PM                        Did you take any photos? Would be very useful for show-and-tell if one is ever asked why wearing the safety gear is necessary.  |  IP: Logged Buck Wilson Jedi Master Film Handler Posts: 894 From: St. Joseph MO, USA Registered: Sep 2010 posted 01-12-2018 06:17 PM                     Phillips. Before warranty was up. The finely obliterated dust was about an inch thick in places in the bottom.  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 01-12-2018 06:28 PM                     That looks like a "film" lamp rather than a DCinema one (DCinema lamps normally have the cable come out of the end rather than out of the side like that.  |  IP: Logged Buck Wilson Jedi Master Film Handler Posts: 894 From: St. Joseph MO, USA Registered: Sep 2010 posted 01-12-2018 07:18 PM                     Well that's news to me, I have no reason to believe we have been using film lamps  |  IP: Logged Leo Enticknap Film God Posts: 7474 From: Loma Linda, CA Registered: Jul 2000 posted 01-12-2018 10:01 PM                        Thanks, and yikes! Interesting that the UV filter appears to have sustained almost no damage. I think I see some debris on it towards the bottom left, but compared to the reflector, it appears to have survived intact. It looks like almost all of the force of the explosion went sideways in all directions, but hardly any went forwards or backwards. Was the triaxial gearbox OK, or had pulverised quartz got into it and clogged the mechanism?  |  IP: Logged Buck Wilson Jedi Master Film Handler Posts: 894 From: St. Joseph MO, USA Registered: Sep 2010 posted 01-13-2018 12:29 AM                     I was surprised the UV glass made it out too. The debris wiped off. It was kinda like when you throw snow at a brick wall and some sticks. I have not tried for myself but it is my understanding that the alignment mech. is a bit 'crunchy' to advance but still works. The UV glass was very difficult to pull out of it's track, though, with all the crap in there. Probably a mix of bits being forced into it while hot, then cooling off... stuck it in there pretty good  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 01-13-2018 11:39 AM                     Three clues that it is a film lamp, the side-mounted anode cable, likely there is no "certification" code in the lamp box, the Cathode (negative) end needs a brass adapter to fit the projector instead of going directly in. Do you have the model number of the lamp (hint, if it says helios, it is a film lamp)?  |  IP: Logged Carsten Kurz Film God Posts: 4340 From: Cologne, NRW, Germany Registered: Aug 2009 posted 01-13-2018 11:52 AM                     So, in the end, how much money was saved in choosing a cheaper lamp over a better one (USHIO)? Only if you have many screens this may pay out on a statistical scale, even if warranty is factored in. - Carsten  |  IP: Logged

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