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Topic: Lamp life ...

Osi Osgood
Film God

Posts: 10204
From: Mountian Home, ID.
Registered: Jul 2005

posted August 16, 2011 01:36 PM

I most often use my EUMIG 926 stereo for projection (unless, of course, I am watching an optical feature), and I know I nput a lamp that had no more than a 25 hour life expentancy ...

... and yet, that thing is still burning bright! I don't get it, but believe me, I am not complaining!

I'll have to do a second check on it, maybe I was wrong about the lamp life.

Could some of this possibly be because the Eumig does allow for the lamp to gradually heat up before being lit?

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"All these moments will be lost in time, just like ... tears, in the rain. "

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Winbert Hutahaean
Film God

Posts: 5468
From: Nouméa, New Caledonia
Registered: Jun 2003

posted August 16, 2011 03:01 PM

Osi, I believe the rate of 25 hours is for continuous on. Therefore if we use it on and off (hence giving the time for lamp to rest) we will have longer live span.

My 2 cents,

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Winbert

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Thomas Dafnides
Expert Film Handler

Posts: 247
From: St. Louis, Missouri USA
Registered: Dec 2009

posted August 16, 2011 06:48 PM

The pre-heated bulb does definitely extend lamp life. This is one of the best features Eumig innovated ( saving $$$ in bulbs ) . If your projector uses the 12v 100w EFP bulb...then I believe it is rated at 50 hours.

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Steve Klare
Film Guy

Posts: 7016
From: Long Island, NY, USA
Registered: Jun 2003

posted August 16, 2011 07:41 PM

Actually continuous runs are better for lamp life. In the 1970s I remember a light bulb in the Guinness book that had been operating since the 1920s and it had been on continuously outside a firehouse.

Most of the abuse a light bulb takes is in the fraction of a second follwing turn on before the filament wire heats up and its resistance rises up enough to limit the current (and power) through itself. Turning on from cold causes a huge surge of current through the filament and forms a hot spot where the wire is thinnest. This boils off a tiny bit of tungsten, which thins it further. After many of these it's so thin it's too fragile to stay in one piece...and zorrrch!

The preheat limits the damage of each surge by starting with warm wire so the starting electrical resistance is higher, so the surge is smaller, so the zorrrch! takes many more starting cycles.

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All I ask is a wide screen and a projector to light her by...

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David Kilderry
Jedi Master Film Handler

Posts: 963
From: Melbourne, Victoria, Australia
Registered: Feb 2006

posted August 16, 2011 09:59 PM

My Eumig 940 with lamp pre-heat (or standby mode as we call it in cinemas) has lamps last for ages. My Elmo ST1200 is not as good. I also received good lamp life from my Sankyo Sound 501; it also had lamp pre-heat.

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Winbert Hutahaean
Film God

Posts: 5468
From: Nouméa, New Caledonia
Registered: Jun 2003

posted August 16, 2011 10:20 PM

Steve, my opinion is based on a simple thought how can the manufacture rate a lamp is 50 hours or 25 hours if they didn't test it on continuous run? and in the same (standard) condition, e.g voltage, wattage, etc

So similar to the test engine for fuel consumption, the rate is based on a standardized condition. However at the hand of customers it can be less or more from that rate depend on how we use the engine and in what condition.

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Winbert

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Steve Klare
Film Guy

Posts: 7016
From: Long Island, NY, USA
Registered: Jun 2003

posted August 17, 2011 08:52 AM

Usually this stuff is according to some established set of conditions: voltage, air temperature, cooling air flow etc. In an application like a projection lamp it would probably be nice if it included so many cycles on and off spaced so much time apart.

It doesn't really matter as much what the standard is as long as all the manufacturers are using it.

Now the conundrum is if we ran a 50 hour lamp steadily it would only last about two days. If we ran it once a night and turned it on and off it might last a year, but only run 40 hours.

How big a reel would you need to run the lamp continuously anyway? (60,000 Feet!)

Could you fit it inside your house?

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All I ask is a wide screen and a projector to light her by...

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Osi Osgood
Film God

Posts: 10204
From: Mountian Home, ID.
Registered: Jul 2005

posted August 17, 2011 10:30 AM

Thanks 4 your opinions gentlemen.

I think it might be getting close to expiration, as the lamp does seem a bit darker these days, but still chugging along! A nice recession proof bulb!

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"All these moments will be lost in time, just like ... tears, in the rain. "

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Winbert Hutahaean
Film God

Posts: 5468
From: Nouméa, New Caledonia
Registered: Jun 2003

posted August 17, 2011 04:49 PM

To sump up, all standard rate e.g length (whose foot?), weight (which pound?), speed (which knot?), volume (which pint? or should I say pint at what country? [Wink]

), lamp live, etc is just a standard made on certain conditions so others can measure what is the approximate measurement for him/her.

cheers

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Winbert

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Thomas Dafnides
Expert Film Handler

Posts: 247
From: St. Louis, Missouri USA
Registered: Dec 2009

posted August 17, 2011 08:25 PM

A question for any electrical gifted minds out there...if the projector is plugged into a surge suppressor... would this suppress the initial damaging surge into a cold bulb and thus, extend bulb life?

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Steve Klare
Film Guy

Posts: 7016
From: Long Island, NY, USA
Registered: Jun 2003

posted August 18, 2011 11:41 AM

Nope!

Surge suppressors are intended to absorb voltage surges causes by stuff like big electric motors kicking in and out and sometimes distant lightning strikes. (Close ones? Forget it!) The bulb problem is a current surge caused by the bulb's electrical characteristics.

I keep my machines on a surge strip because I want to protect the semiconductors in my sound boards from my wife's air conditioner, clothes washer and dishwasher, but that's a different thing.

Materials change in electrical resistance as they heat up. Some go down in resistance, which means their current at the same voltage will rise (power too). These will run away and blow up if they aren't kept cool enough. Metals (like the wire in a bulb filament) go UP in resistance, which means their current and power at the same voltage will fall as they heat up.

It does mean they are low in resistance when they are cold, which means that initial burst of current can be multiples higher until the temperature and resistance come up to level things off at a normal level. If there is a small segment of the filament that is higher in resistance than the rest, it will get very hot, very fast.

Think about all the incandescent light bulbs you've ever had blow out on you: probably the majority are when you first turn them on. This is the moment they are beat up the worst.

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All I ask is a wide screen and a projector to light her by...

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Osi Osgood
Film God

Posts: 10204
From: Mountian Home, ID.
Registered: Jul 2005

posted August 18, 2011 12:40 PM

Hey, I know what I'll do ...

I'll watch "BEN HUR" tonight! That's a three and a half hour super 8 treat, in scope to boot! Lets see if I burn out that baby this time!

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"All these moments will be lost in time, just like ... tears, in the rain. "

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