Buying replacement lamps

J

jamani

Active member
Just wondering how you guys go about buying replacement lamps for your tungsten fixtures especially if you use old theatrical lights. All my fixtures came with labels that tell you what lamps to use but a google search produces a myriad results with some going by a different name but the name I'm looking for listed under "cross reference". Does this mean that the same lamp may go by different names? And how about those results that don't have a "cross reference" list but look like the lamp you are looking for? How do you tell whether it will work with your fixture? I ask because the prices on all these results are all-over the place and I'm looking for the best deals. If it helps at the moment I'm looking for a 176-097 EGT lamp for a 1k Colortran fresnel. Some results just have "EGT" on them and no other numbers.

And while at it maybe someone can enlighten me on what causes lamps to burn out so fast. I'm talking less than two hrs of use for lamps that are rates for 200hrs. I'm in the market for replacement lamps because the last time I used my lights (which happened to be my first time too) two of the above-mentioned lamps burned out on me in less than two hours. What are some standard practices to observe or avoid to prevent this? I think I read somewhere something about not holding them with your bare hands or else they get oil on them? How about how often to turn them off and on during a shoot? Do they need to cool down before they are fired up again?

Thanks for any insight.
 
You're talking about Colortran, which put some weird meaningless sequence of numbers in front of the ANSI code on all their lamps.
This may help, it's also the company I usually get my bulbs from - http://www.barbizon.com/store.php?cPath=1

And yes, that little thing you mention about not touching the glass envelope with your bare fingers is EXTREMELY important. If you do, clean it all off. Most people recommend using rubbing alcohol, I find that wiping it off with a tissue using a lot of pressure works fine. But if it's a larger, more expensive bulb like for a 10k, you'd probably want to use rubbing alcohol just to be safe.

How are your lamps burning out? If they're actually exploding, touching them would be the culprit. Using a dimmer when you need less output as opposed to scrims or walking the light back can significantly preserve the life of the lamp. The filament doesn't burn as hot when dimmed, so less tungsten evaporates away.

Tungsten lamps don't need to be cooled down before striking them again, at all. It's a good practice to do this with HMI's though, hot restrikes with those can put more wear on the lamp than a cold strike. And with some types of lamps like the the LEP's and CID's, it's flat out impossible to do a hot restrike.
 
You're talking about Colortran, which put some weird meaningless sequence of numbers in front of the ANSI code on all their lamps.
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I take it the "ANSI code" in this case would be "EGT"? So how does this work? Anything with "EGT" in the name should be able to work on my fixture?

How are your lamps burning out? If they're actually exploding, touching them would be the culprit
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They are not exploding. They just go off and when I check they are discolored (black) and burned out.
 
If they receive rough handling while hot, that can cause the filament to break prematurely. I usually let them cool down a bit before packing them up and transporting them.
 
jamani said:
I take it the "ANSI code" in this case would be "EGT"? So how does this work? Anything with "EGT" in the name should be able to work on my fixture?



They are not exploding. They just go off and when I check they are discolored (black) and burned out.
Click to expand...

EGT is the ANSI code. If they are black they are bad. How long are they lasting?
 
jamani said:
Two of them lasted only about an hour each
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If they are completely black and discolored it could be an air leak, caused by a manufacturing defect. I've seen bad batches of bulbs like that from brand names like osram.
 
Quick question. The black marks, I don't suppose they're fingerprints are they. Not everyone realises you must never touch a halogen lamp with your fingers. If you do, the natural oil in your skin sits on the lamp. To make the halogen cycle work, the lamp envelope will be really hot. The oil blackens with the heat, and the dark spot (think cars on a sunny day) gets hotter, so darkens, so gets hotter etc etc and in a very short time there is a very dark spot where your fingers touched. This blackening means the envelope will be running too hot and often the pinch seal at the lampholder end will fail, and the lamp dies. It's vital that you do NOT touch the lamp with naked fingers. I'm guessing but the black spots to me indicate a finger and thumb - where the lamp was inserted? Disposable gloves, or even a bit of cardboard will do. If you accidentally touch your new lamp, then some kind of solvent will remove the grease. Meths, alcohol - anything the dissolves and evaporate will usually do.
 
The gray / black marks that I've come across are from the filament being broken in such a way that it begins to burn excessively hot. It then deposits tungsten onto the inside of the quartz envelope faster than the halogen cycle can work to bring it back to the filament. I usually see this happen with coiled-coil type lamps.

Similarly, if the bulb has a small crack, it will do the same since the halogen gases get pushed out. When this happens, the inside of the globe winds up with a light yellow coating first, which after several seconds will darken.

Or if it suddenly burns out, the associated arc can cause enough heat to evaporate some of the filament and cause a mark.
 
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