old arri 1k burning through globes after only three days of use?

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dv416

Well-known member
I have an older (1980s) model arri 1k that has burned through a brand new 1k bulb after only three shooting days worth of use.

There was no misuse / abuse of the light. The lamp just went out. Have you heard of anything like this happening?

I don't have the light in front of me right now, but I was told that the globe might not fit 100% securely in the socket. Was there a bulb / socket design change over the years since the 80s that might explain this? So that a new 1k bulb wouldn't fit properly in an older 1k light? And would then zap the bulb's lifespan??

What is the diagnosis usually when a bulb burns out way too fast?

Any help is appreciated. Thanks!
 
You might want to get it tested and tagged as a precaution for safety (not a bad idea anyway, it's cheap and goes some way to removing negligence from the table if your light starts a fire or shocks someone) but one blown bulb is not a pattern. It could just be a bad bulb. If it happens a second time I would be concerned. I don't know whether the design of the bulb would change but I would say it's very unlikely. The manufacturing process might change but any significant modification of the design will result in a new model designation. If the bulb wasn't properly installed that could easily cause the problem described. Also consider cleaning the contacts, 30 years of tarnish could prevent a good make as much as a poorly seated bulb.
 
I'd think it would take less than a few days for it to blow out if it were touched. And for someone who knows the term "globe", I'd hope that he knows that rule.

Are you sure the lamp was brand new? What does the blown lamp look like? is it all blackened or is there just a discontinuity of some sort in the filament? Did you notice it doing any strange things right before it blew out? If there's the slightest crack in the quartz, when you fire it up it will fairly quickly get very dim compared to normal and put out a yellow cast, slowly going back to normal color but getting dimmer (this is the actual filament evaporating and being deposited onto the quartz envelope). This could have happened if the light took good impact.

I highly doubt it has anything to do with the fixture though, tungsten lights are extremely simple by design. The exact same electricity coming out of your wall receptacle is going uninterrupted into the lamp, no electronic components are there to do any damage unless you overdrove it with a variac.
 
What J Davis said. +Ever. Residue from your fingers,etc, causes a hot spot to develop and blow the globe. Sometimes sooner, sometimes later, but it will cause the globe to blow pretty quickly. Always hold the globe by the sleeve in which is comes.
 
Thanks for the replies, y'all.

I know about the not touching rule, yes. I'm actually asking this on behalf of someone else who has been handling the gear, so I don't know first hand how its been handled in this case. All I know is the bulb went out very prematurely. He claims he didn't touch the light with his fingers, but only the base as he put it into the socket. I told him to not even do that in the future.

I highly doubt its the fixture too. These things aren't rocket science. Rudimentary circuits, in big metal cases. The only thing that raised an eyebrow for me, was that apparently the bulb does not fit 100% securely in the socket. Now again, I don't know if Arri has really changed designs over the years. It look just like every other arri 1k I've ever seen. This one however, IS from 1988, so you never know I guess.

Can someonw explain what exactly about a bad socket would lessen the lifespan of the bulb? Assuming the light works, the circuit is intact, and 1000 watts are drawn consistently, why would even the socket affect the bulb's lifespan?
 
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Because a loose fitting socket allows arcing between socket and contact and that is never good for a tungsten (or any for that matter) bulb. If you try another bulb and nothing happens then it was a fluke. If another one goes bad soon though, its probably the socket. In the GY9.5 type socket, its happens sometimes because there is a small pin and large pin If people force the bulb in the wrong way, which they do sometimes, then it stretches out the small pin socket and the next time someone puts the bulb in correctly, arcing is very common making the bulb blow prematurely.
 
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Normally if the socket were the cause you'd see some kind of pitting or burning on at least one contact of the bulb. I would say that changing the socket would probably be a good idea and this would allow a re-visiting of the wiring inside the fresnel too to make sure its all connected as it should be. Find out what kind of socket it is and look online for a replacement.
 
We still don't know if this is a pattern or a one time incident.
dv416 said:
I'm actually asking this on behalf of someone else who has been handling the gear, so I don't know first hand how its been handled in this case.
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Not to point any fingers but my observation has been that almost nobody treats gear that's not theirs quite as well as gear that is, whether they realize it or not. But in this case, it really wouldn't even need to be mishandled, a hot filament is extremely fragile. I've had 1k lamps go bad older Mole lights just from focusing them when the lamp / reflector assembly slams into the end of it's travel. Just a small bump could have done it.
 
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