Community Theater Green Room Discussion Board: single filament lamp failure

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   I just had 3 GLA lamps fail in a row. They failed while focusing the fixture.
The first one might be excusable because I did jar the fixture, but I was
trying to be careful when the other 2 failed.

These all had a single large filament. I just read that the orientation of this
filament matters. It is important to orient the lamp so that the support is
above the filament, otherwise the filament can fail by bumping the
support and shorting out. This was news to me.

GLAs are available in a concentrated filament design (multiple filaments
on a rack). Are these more resistant to shock? There is a brighter lamp
known as a GLC but the rated life is substantially shorter. Someone
suggested that the GLC was more reliable.

Does anyone have anything to offer on this subject?

David 

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David McCall Celebrity Joined: 1/28/09 Location: United States Online Status: Offline Posts: 299	Topic: single filament lamp failure Posted: 7/29/09 at 5:01pm
	I just had 3 GLA lamps fail in a row. They failed while focusing the fixture. The first one might be excusable because I did jar the fixture, but I was trying to be careful when the other 2 failed. These all had a single large filament. I just read that the orientation of this filament matters. It is important to orient the lamp so that the support is above the filament, otherwise the filament can fail by bumping the support and shorting out. This was news to me. GLAs are available in a concentrated filament design (multiple filaments on a rack). Are these more resistant to shock? There is a brighter lamp known as a GLC but the rated life is substantially shorter. Someone suggested that the GLC was more reliable. Does anyone have anything to offer on this subject? David
	David M

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Gaafa Celebrity Joined: 3/21/04 Location: Australia Online Status: Offline Posts: 1181	Posted: 8/01/09 at 9:53pm
	The problem might be with the latern, it's self, rather than lamps. I'm sure you would have tried another latern unit, with same type lamp bubbles - it may be something as simple, if you have not had the problem before? This site may help:- http://www.donsbulbs.com/cgi-bin/r/t.pl/failures.html Have you checked with your Lamp Distributor, they could have had this problem with this brand before? The only problem I have experianced before, is when a young TIT [Techie In Training] was found to be changing the bubble & not using a condom, when handling it. But from your post, I doubt this would be a problem & usualy it will work untill the glass envelope becomes pregnant 'n pops out. {Funny how the lamp never does seam to ever spawn an offspring globe either?] As for filament reinforcement, unlike the old incandecent "T' series lamps, although they had a lot of element rack reinforcement, when they became hot, they were very delicate & tended to sag as well over time. With the inert gas filled bubbles, I have never had that same type problem.
	Joe Western Gondawandaland turn right @ Perth. Hear the light & see the sound. Toi Toi Toi Chookas {{"chook [chicken] it is"} May you always play to a full house}
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Topic: single filament lamp failure( Topic Closed)