This is topic Any problems with OSRAM "Classic" bulbs? in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.


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Posted by Jon P. Inghram (Member # 4125) on 06-21-2008, 12:28 PM:
 
Anyone has any problems with these? We just replaced a XBO 4000W/HS CL OFR after only 1318 hours because the arc was unstable and off-center and the anode end of the bulb was developing an disturbing looking blotchy blackening, not just the regular over-all darkening that an old bulb develops.

The last two bulbs (both "regular" XBO 4000W/HS OFRs) ran for 6882 and 4716 hours in that particular lamphouse, a Big Sky.
 

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Posted by Louis Bornwasser (Member # 3063) on 06-21-2008, 03:30 PM:
 
You've answered your own question: 2 are good, one is bad. It is always possible to get a random bad bulb, especially if seal damage is the culprit. Louis
 

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Posted by Tim Reed (Member # 137) on 06-21-2008, 05:23 PM:
 
How many hours are 4000 HS's warrantied for?
 

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Posted by Troy Hilsman Powell (Member # 4326) on 06-21-2008, 05:47 PM:
 
Sounds like low gas pressure in the bulb but you better check your air cool flow on the bulb.
 

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Posted by Jon P. Inghram (Member # 4125) on 06-21-2008, 07:58 PM:
 
The normal and "Classic Line" models are now 1000 hours, the "Xtreme Life" model is 1500. I think they used to be rated at 2000 hours, but I might be wrong on that. The lamphouse airflow is good.

The replacement bulb is a XL model, but (hopefully) we'll have new projectors before we find out if it actually lasts any longer.
 

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Posted by Tim Reed (Member # 137) on 06-21-2008, 11:46 PM:
 
I remember them being warrantied anywhere from 800-1200 hours years ago. I was just wondering if something had changed dramatically recently. 6800 hours is pushing it.
 

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Posted by Monte L Fullmer (Member # 2797) on 06-22-2008, 12:12 AM:
 
Dang, how did the light output look like with 6800 hrs on a bulb with an 800 hr warranty?

Some serious hours there when it should have been pulled around 2000hrs..
 

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Posted by Mark Gulbrandsen (Member # 72) on 06-22-2008, 10:10 AM:
 
Actually the Redwood Drive in SLC that also utiizes those nifty Canadian reflector conversons typically gets 3,000 hours out of their Osram 4kw's, they also come out more or less clear. The result of using hurricane blowers.

The blotchy black is due to the fact that today's lamps have a "getter" in them. This "getter" attracts the spent tungsten that is vaporized during lamp operation. So a little blotchy black is perfectly acceptable although indicative of lots of lamp hours and possibly not enough lamp cooling. Back when lamps did not have those "getters" in them lamps more or less turned black evenly on the inside creating a dangerous situation where internal heat could not escape fast enough.

Mark
 

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Posted by Monte L Fullmer (Member # 2797) on 06-22-2008, 01:08 PM:
 
what about quartz derivication (excuse the spelling) when quartz gets the hours on it?
 

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Posted by Mark Gulbrandsen (Member # 72) on 06-22-2008, 03:31 PM:
 
Thats hard to say Monte... I'm hardly a glass expert but typically when a lamp explodes from high hours its no doubt due in part due to vitrification of the glass. Considering that we havae customers that run CXL20 and 20R lamps well past 20K hours its certainly a non issue until the lamp reaches extremely high hours. What I typically see on the 20's at those high hours is that the lamp is finally unstable... amazingly, the envelopes are still clear.

Mark
 

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Posted by Monte L Fullmer (Member # 2797) on 06-23-2008, 12:27 AM:
 

quote: Mark Gulbrandsen

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amazingly, the envelopes are still clear.

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..which I've also experienced with 20R bulbs with over 7k hours on a few occasions - but new better of the needed changeout in case one does let go in our X90's and I'd have to give a fully detailed explanation on why I let a bulb stay in a console too long ... and obviously I don't want to be engaged in that war-a war that I'd win that battle in defense, but still lose the war in the long run.

-Monte
 

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Posted by Jon P. Inghram (Member # 4125) on 06-23-2008, 12:27 PM:
 
The bulb that hit 6882 hours was replaced because it was flickering. The bulbs have averaged 4383 hours, and were replaced half the time because they started to flicker, and the other half because they were getting dim.
 

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Posted by Jon P. Inghram (Member # 4125) on 11-01-2008, 01:50 PM:
 
Had another 4k OSRAM Classic bulb kick the bucket at only 1005 hours. It had been running perfectly, but when I went to start it this morning the arc spread across the entire inside of the bulb and was very, very dim. My guess was that it developed a leak, which was confirmed when we pulled it out: It looked like blue frosted glass on the inside of the bulb.
 

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Posted by Mike Olpin (Member # 1115) on 11-01-2008, 02:07 PM:
 
A bit off topic -

I love it when I find a strange lamphouse that for whatever reason allows ungodly long bulb life. #3 at Rancho San Diego (Christie SLC, CXL-40) was like that. The image stayed perfectly steady and bright after 2-3000 hours! I never had to pull a bulb out of it due to flickering or brightness, always pulled bulbs due to age, nothing else. By far the brightest and sharpest machine in that complex.

What weird voodoo causes this? I didn't treat it any differently than the others.
 

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Posted by Tony Bandiera Jr (Member # 2365) on 11-01-2008, 02:38 PM:
 
At one major art house chain here in L.A. the chief projectionist had discovered that he could get much extended bulb life by killing the LAMPHOUSE blowers immediately at show end, leaving the stack exhaust running. (I should mention that unlike the majority of installations I have run across, all his theatre's stacks had at LEAST 550cfm measured at the lamphouse.)

Prior to doing this, he would average just above warranty life on the bulbs (virtually all were Osram 4k), after changing the lamphouse wiring to kill the blowers on shutdown, bulb life was well over 5k-6k hours each.

Lamphouses are LP Associates 8540s.

quote: Monte L Fullmer

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Dang, how did the light output look like with 6800 hrs on a bulb with an 800 hr warranty?

Some serious hours there when it should have been pulled around 2000hrs

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Monte, when I started in this business back in '82 I was of the "pull the bulb at warranty hours" school. But since then, not only have bulb technologies improved, but user experience has shown that is is far wiser to only change bulbs if they are hard to start, flicker or have excessive darkening of the envelope. Over literally hundreds of screens and many years that I have been around, I can count on one hand the number of bulb explosions.

Better to leave a sleeping dog lie, or in this case, a working bulb alone.
 

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Posted by Jon P. Inghram (Member # 4125) on 11-01-2008, 08:53 PM:
 
I wonder if we just got a bad batch of bulbs or something. As far as I know, none the "Classic Line" 4k bulbs have made it past 2000 hours in our lamphouses.






 

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Posted by Monte L Fullmer (Member # 2797) on 11-01-2008, 09:40 PM:
 
Yep, seal leakage causing that to go blue.

I've never like the way Osrams are constructed with those quartz donuts next to the envelope holding the shafts of the electrodes in place. Just any sort of heat flexing of those shafts would cause some leakage of sorts..and I be this example here is a good probable cause

With Christies, that's all solid quartz from envelope to about an inch from the seals - hardly any chance of gas leakage.

I thought 4k bulbs are only warranted 900 hrs. Thus, if you can pull close to 2000 hrs, I'd call that pretty good.

quote: Tony Bandiera Jr

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I was of the "pull the bulb at warranty hours" school.

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quote: Marco Giustini

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on the anode be sign of overheating or is it caused by the gas leaking?

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The anode just suddenly discolored from being suddenly exposed to the oxygen that is burnt off in the bulb.

-Monte
 

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Posted by Jon P. Inghram (Member # 4125) on 11-02-2008, 12:27 AM:
 
Yep, they don't hold up very well when pretending to be a carbon arc lamp.

The lamp had worked perfectly yesterday, and when it first struck this morning it started fine on the first strike but the arc, instead of stabilizing in the proper spot, curved up inside the bulb and then spread out into a diffuse glow with a brighter spot in the normal location.

The CL bulbs are warranted for 1000 hours, the XL ones 1500.

Those disks do appear to have kept the burnt tungsten fumes confined to the middle of the bulb, and anyway they're really only meant to hold the electrodes in place and to keep the hot xenon gas from flowing directly to the end seals and overheating them.
 

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Posted by Louis Belloisy (Member # 3836) on 11-02-2008, 03:06 PM:
 
How many of you are burning bulbs in the vertical position. we have 4 simplex that burn horizontal and two old victoria 4's that burn vertical.

the horizontal burning bulbs average 2 years = about 2k hours
the vic 4's with the vertical average 3 - 4 years = 3 to 4k hours. Vertical burning is definitely the winner.

louis
 

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Posted by Louis Bornwasser (Member # 3063) on 11-02-2008, 06:50 PM:
 
Why would your dealer sell you "Classic?" The "XL" are better warranty and the same price!! Louis
 

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Posted by Mark Gulbrandsen (Member # 72) on 11-02-2008, 08:55 PM:
 
Unless your lamphouse gets a few more lumens using the Osrams because of possible reflector/lamp interaction then definately leave the Osrams behind and go with Christie Lamps. They can't be beat.

Mark
 

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Posted by Jon P. Inghram (Member # 4125) on 11-03-2008, 10:19 PM:
 
Us projectionists are not exactly part of the purchasing and/or decision making process. We don't even have keys to the lamphouses, and our primary tools are a pair of pliers and butterknives. If those don't cut it it's time to call the tech.

Hopefully we'll be using Christie bulbs by next year, although that change won't have anything to do with the lamphouses we're currently using...
 

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Posted by Monte L Fullmer (Member # 2797) on 11-04-2008, 12:39 AM:
 

quote: Jon P. Inghram

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We don't even have keys to the lamphouses, and our primary tools are a pair of pliers and butterknives. If those don't cut it it's time to call the tech.

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