Film-Tech Forum ARCHIVE: Whats up with my xenon bulb?

This is topic Whats up with my xenon bulb? in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Brian Dooda (Member # 3941) on 10-31-2009, 11:50 AM:

This Osram XBO2000 W/H was new and put in five months ago. It only has 300 hours on it. Installed in a Xenex II lamphouse it ran at 75 amps. Fan and exhaust are all good. I noticed a month or so ago it started to develop these smokey gray spots on the forward top side inside the bulb, also a line of small bubbly gray deposits towards the rear. This has not happened with bulbs previous. What's going on?
Thanks,
Brian

Posted by Sean McKinnon (Member # 612) on 10-31-2009, 12:18 PM:

I may be wrong here but it looks like it could have been caused by a contaminent on the quartz envelope of the lamp ie; oil from human skin contact. Or possibly a defect in the quartz itself. I would think if it was an issue of improper cooling or a seal problem you would see more widespread and even darkening of the quartz.

Either way I would remove this lamp from service ASAP as any defect like this could lead to a catastrophic failure while operating and take out your reflector and cause an unhappy crowd when the light goes out mid show.

I would send it back to Osram for analysis especially if it is under warranty hours. They may say that it was caused by the theatre and not pay for a replacement but at least you would get a definite asnwer as to what happened here.

Posted by Monte L Fullmer (Member # 2797) on 10-31-2009, 12:56 PM:

It's an OSRAM - seen that many times with this brand of bulb.

Try Christies next time.... Never had any sort of this kind of problem with Christies...

Good luck-Monte

Posted by Karl Borowski (Member # 5424) on 10-31-2009, 06:20 PM:

If Sean is right, though, that sort of thing would happen with Christie bulbs too. Any idea Brian?

Quartz bulbs should NEVER be touched with bare hands. Given the cost of film projector bulbs, its surprising how many people I have run into in booths that do not know this simple bit of information.

Posted by Brian Dooda (Member # 3941) on 10-31-2009, 07:09 PM:

I'm pretty sure it wasn't touched. I haven't worn gloves in the past but am aware and careful about all that. I think that the discoloring is on the top side is a clue for something, I just don't know what.

Posted by Michael Schaffer (Member # 1204) on 10-31-2009, 07:57 PM:

It definitely is a clue: for oxidation. The lamp is leaking xenon gas and allows air in. Normally when that happens, the whole bulb envelope gets discolored in broad grey/blue/black streaks.

Sean is right - send it back for a warranty replacement. The only reason I could see for them to turn down a warranty replacement is if the metal endpieces are significantly discolored, too - meaning they turned copperish dark brown or even blue. That would indicate that the metal has overheated because you made a loose connection when you installed it, and the lamp is now leaking because of that. If the endpieces look clean and silver, they have no reason to deny a warranty replacement.
Good luck.

Posted by Monte L Fullmer (Member # 2797) on 10-31-2009, 08:22 PM:

(Sorry to be a bit on the cranky side about Osrams..we never had the good luck with them as we do with running Christies..)

True, hopefully that Osram/Sylvania will honor a warranty with this bulb condition..

(for that was another reason for our change was warranty denials on three bulbs that did similar to what this example shown here was....and we were denied warranty since they said that this was caused by our system having poor exhaust/handling procedures .."Gee, they never been here in my booth before, how can they make such an statement like that..?" They lost our business real quick..)

Posted by Jim Cassedy (Member # 4115) on 10-31-2009, 09:19 PM:

I had something similar only the spots were a little
darker when we tried Osram bulbs in a Xenex II after
about 800hrs. We were able to send it back and get
a replacement, and he same thing happened. We switched
back to Christies and haven't had the problem since.

Posted by Ian Parfrey (Member # 5122) on 10-31-2009, 09:45 PM:

Christie = Ushio

Posted by Paavo Mardi (Member # 4962) on 11-01-2009, 03:48 AM:

It must be a Osram Classic Line bulb. These spots appear when the arc overshoots the anode. It's a bad bulb, adjusting the stabilizing magnet does'nt help.