8mm Forum: Xenon GS help.

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Topic: Xenon GS help.

Alan Gouger
Master Film Handler

Posts: 451
From: Florida
Registered: Jun 2003

posted January 20, 2004 02:25 PM

Hi Guys
Xenon bulb blues.
I just bought this projector a month ago and have only used it 3 times. Well I just plugged it in, thread the film and go to ignite the bulb and Pop and sparks" wow so I shut it down. I tried again with the same results. I do not want to try anymore because I dont want the sparks or voltage to take out another part of the projector.

Does this sound like a typical xenon lamp failer?

Singin the blues.

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Alan Rik
Film God

Posts: 2211
From: New York City, NY, USA
Registered: Jun 2003

posted January 20, 2004 05:01 PM

Alan,
I have never heard of that happening with any of the 3 Xenon's I have owned including that one.
Is it different than the buzzing sound you get sometimes when you try to ignite the lamp and it was just turned off?

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John Whittle
Jedi Master Film Handler

Posts: 791
From: Northridge, CA USA
Registered: Jun 2003

posted January 20, 2004 06:54 PM

Normal start of a xenon lamp you'll hear a snap and see a bright "spark" which is the high voltage jumping the electrodes inside the lamp and causing the gas to excite and give off light. Then the voltage drops and the steady dc keeps the gas excited.

Now as the lamp gets older it gets harder to strike. First when it's warm and re-strike may take several sparks and later still cold it'll take several sparks before the lamp ignites.

If this isn't what you're seeing, you might have something as simple as dust or dirt across the spark gap (which is inside the projector and part of the high voltage striking circuit) which is bleeding the high voltage off before it can get to the lamp. Or you could have an old or damaged lamp.

Carefully check all the connections and look for unusual signs of arcing (black or burned areas).

Aside from that you'll need someone or yourself with a good schematic and the ability to trace out the circuit. Since these are switching supplies they are a bit complicated. You might see if there's still anyone at Elmo that has some suggestions.

John

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Daryl C. W. O'Shea
Film Handler

Posts: 35
From: Midland Ontario Canada
Registered: Jun 2003

posted January 20, 2004 11:56 PM

Assuming that you have a metal reflector in this lamphouse and the lamp is connected with non-jacketed cables, it's most likely that the cable is arcing to the mirror.

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Alan Gouger
Master Film Handler

Posts: 451
From: Florida
Registered: Jun 2003

posted January 21, 2004 09:45 AM

Daryl

This sounds like whats happening. I assume you mean with the dead bulb. The current has no where to go because the bulb is shorted or dead so its arching, correct.

John

Ive looked at everything and nothing looks out of place or burnt.
I guess the next step is to get a replacement bulb and keep my fingers crossed.

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John Whittle
Jedi Master Film Handler

Posts: 791
From: Northridge, CA USA
Registered: Jun 2003

posted January 21, 2004 06:04 PM

You might check with Superior Quartz Products. I think Steve sent them a bulb to clone for replacement production. If you have access to another projector, try the bulb from it in your machine to double check before you lay out $300 or so for a new bulb.

John

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Daryl C. W. O'Shea
Film Handler

Posts: 35
From: Midland Ontario Canada
Registered: Jun 2003

posted January 21, 2004 08:49 PM

That's not actually what I meant, but it tells me a little more.

Just because a lamp is 'dead' it wouldn't cause it to arc to the mirror, etc. If anything was close enough to the mirror it would arc to it regardless of whether the lamp was any good... and the lamp may still light.

Anyway... since you've said you've seen no discolouration of anything, I assume that there are no arcing marks on the mirror either. So, in all likelihood the lamp is probably just dead... possibly a failed seal.

If the lamp is dead, you will hear it trying to ignite the lamp (trying to arc the gap between electrodes). It'll do this all day long if the lamp has depressurized (not that you should do it all day long). If this is the case replacing the lamp should be it.

Has the lamp envelope itself discoloured at all? Can you post a picture of it?

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