Film-Tech Forum ARCHIVE: Xenon lamp failure

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Posted by Ray Bernardi (Member # 1615) on 06-04-2003, 01:31 PM:

Last night during the final credits my lamp shut down. There was no overheat condition, all fans were functional. It just plain shut off. No cue from the automation caused it, there was nothing going on when it decided to go away.

After about 10 minutes or so I was able to strike it again and it didn't look good at all. The lamp was way high on the screen vertically. Nobody but me touches those adjustments and it was fine before it failed. The lamp has a flutter in it now that it did not have before.

I removed the lamp and it looks fine. The elements are clean, no pitting, no obvious sign of any damage, no apparent sag etc.

I have no idea what went wrong last night. I hate it when I can't pinpoint a cause of a failure. It does not give me a warm fuzzy feeling at all.

Here's some other info -

It's a 1600 watt bulb that I'm probably powering up at 1000 watts at best. I need a new rectifier. I'm looking. Here's the funny bit. After I strike the lamp, to get rid of the shake, I back down the power coming out of the rectifier. It gets stable, it looks okay. If I run the rectifier back up to full power, it shakes.

I guess I'm looking for ideas here. Do I have a lamp problem or a rectifier problem, or both?

Any help would be appreciated guys.

Thanks.

Posted by Jeff Taylor (Member # 443) on 06-04-2003, 01:37 PM:

Starting with the obvious such as all connections tight, no sign of blackening or overheating anywhere, and assuming it's a reactance type rectifier I guess I would lean toward a diode breaking down under full load.

Posted by Ray Bernardi (Member # 1615) on 06-04-2003, 01:41 PM:

All connections are tight. I'll check again to be sure. There is a slight black area on the bulb but it was not at the 12 o'clock position so I figure it happened at some point in the past.

I've been leaning toward a rectifier problem myself.

Now where's the nearest radio shack??????

EDIT - Woooo Hooooo - Post number 100 (thank you 3 word game....)

Posted by Don Sneed (Member # 955) on 06-04-2003, 07:14 PM:

Ray, a wee bit more info...what make & model is lamphouse, did the lamp ever strike up again ??? as you may know every lamphouse & projector has it's own problems, knowing which make & model, most of us techs can solve the problem by knowing the above, example is Ballantyne projectors always has 5-problems, century has three, Christie has four, the same is true with lamphouses & consoles, knowing which make & model of lamphouse & rectifier can help us solve your problem...now for a question, did the lamp ever came back on, was it only a one time problem...knowing this we can help....

Posted by Mike Pennell (Member # 1692) on 06-04-2003, 10:43 PM:

Hey Don, How ya doin'? Just saw Stan this weekend. [beer]

Posted by John Hawkinson (Member # 1135) on 06-04-2003, 10:54 PM:

Also, Ray, can you please post the current consumption levels (in amps), both what you're been running it at and what back it off from?

--jhawk

Posted by Ray Bernardi (Member # 1615) on 06-05-2003, 09:48 AM:

It's a Xetron XH series lamphouse. I have an Irem rectifier. I don't know it's model offhand. My projector meters show about 58 amps and about 20 volts. (or the other way around?? - damn I'm tired) The bulb is a LTIX-1600W-SHR. The bulb did re-strike. It was used during last nights show. I had a hell of a time getting it to focus. I had a halo effect on the screen for a bit but I finally got rid of it.

I am looking into a new rectifier that can provide the power the bulb needs. I'm seriously under powered at the moment. I'm getting quotes in the 2000 to 3000 dollar range.

I'm going to put a WANTED in the equipment section. If anybody has anything I can use please let me know. I just dumped almost 20K into this theatre and another 3K at this point would be very very painful to me.

Thanks guys.

Posted by Jeff Taylor (Member # 443) on 06-05-2003, 11:12 AM:

Ray: I have to admit being a bit stumped by some of your symptoms and problems. It sounds to me that you're a bit under voltage and substantially under amperage for a 1600w bulb. Given that it does strike, I'm surprised you're not having more problems with lamp blackening, and also by your ongoing erratic focus problems. Apparently the arc is misbehaving under the circumstances causing the focus problems, but I'm surprised they're so severe. Using the rule of thumb that a lamp shouldn't be operated at less than 80% of rated output, you probably shouldn't go less than about 1300w (as compared to your estimated 1000w), and I'm GUESSING that probably equates to a minimum of around 60 amps. Of course, there's no assurance that your meters are dead on. Just out of curiosity, how long had it been since you could go to full power without having the flickering?

Posted by Ray Bernardi (Member # 1615) on 06-05-2003, 01:13 PM:

Jeff - It just happened two nights ago. Before then all was fine. Now I have trouble. I'm going to need to get the new rectifier I'm afraid.

Posted by Jack Ondracek (Member # 1466) on 06-05-2003, 02:17 PM:

Ray... do you have another lamphouse you can try that bulb in before you go to the extreme of replacing the rectifier?

Posted by Travis Hubrig (Member # 1745) on 06-05-2003, 04:50 PM:

I am running 1600w osrams, and I am running a slightly higher voltage (20-25) but 59-65 amps depending on the age of the bulb...
I am running with XHN Lamphouses and Xetron N3 series rectifiers...
I have had bulbs shut off when a diode gets bad. Sometimes they will strike again for me.
It could be possible that you have multiple diodes that are bad.
It is odd that your flicker will go away with less power, I haven't seen that.
I would try replacing all diodes in the rectifier. And possibly moving the bulb.

How many hours on your bulb?

Posted by Gregory N. Jones (Member # 805) on 06-06-2003, 09:47 AM:

Ray,

It does sound like a diode problem but give us a call at 800-526-0722 and ask for Brian Monahan. Changing the diodes out will save you a lot of cash instead of buying a brand new rectifier.

Gregory N. Jones
Neumade Products Corp.

Posted by Ray Bernardi (Member # 1615) on 06-07-2003, 06:37 AM:

Greg - I'll give Brian a shout. A question, changing the diodes is not going to give me the extra power I need is it? I'm thinking of replacing the rectifier because I'm so under powered at the moment.

Posted by German Marin (Member # 918) on 06-07-2003, 12:22 PM:

Ray, LTI lamps starts they work at 85% of current setting (e.g. a 3000W/H lamp starts its life (1200 Hrs + 25%) at 85A and it needs to increase during its halflife to 100A even 110A at the end of its life). If we don't do this the light begin to loss shine. I've worked with LTI lamps and I prefer to use Osram (be careful with LTI's plastic protective box, if the lamp explode the protector will do too!).
Maybe the rectifier doesn't have enough power to keeps the light on.

Posted by Travis Hubrig (Member # 1745) on 06-07-2003, 01:50 PM:

Just a thought...
In the XH I am not sure,
But In the XHN the OSRAM 1600w, uses the same adapters for the OSRAM 1000w. If a smaller bulb can still light his screen is it possible to switch down to it?