8mm Forum: Xenon lamp strike question

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Posted by Claus Harding (Member # 702) on August 25, 2009, 10:01 PM:

I noticed on my Eiki 3500 that the 350W lamp seems to be more reluctant to 'hit' the first time if the lamp selector is on low, so I just wanted to throw this out there for anyone who has had issues (I was starting it on low to make the "hit" more gentle, but I may have used the wrong logic here.)

On the 'High' setting, it strikes cleanly the first time, and the lamp is obviously happier for that (as is my wallet), but I just wanted to know if any of the Eiki/Elmo owners have had any issues with this.
What are the power issues on an Eiki in terms of lamp strike voltage between 'high' and 'low' settings, if any, or is it an issue with the lamp and my ignorance of the above? Is the voltage the same regardless of the two settings when you first fire up?
The commercial machines I have run, you bang 'em on and there they are, so I just wanted to see if this had been an issue with anyone.

Thanks as always for any help you can offer.

Claus.

Posted by Kevin Faulkner (Member # 6) on August 26, 2009, 04:23 AM:

Normally with these Xenon Power supplies it doesnt matter which setting the lamp power is set to. A very high voltage (30,000 Volts) at low current is used to strike the lamp. When the lamp strikes the power supply throttles back to about 24 volts but at highish current. It may be better to start with the lamp setting at its higest setting just to start with and then drop it back to the lower setting once it's running. There are manufacturing tolerances on these lamps and it may be this one is at the lower end of it spec so needs the slightly higher runnning voltage when the lamp strikes and the supply throttles back. Its difficult to expalin the workings in laymans terms so I hope that sorta gets across what I'm trying to say.

Kev.

Posted by Steven Sigel (Member # 21) on August 26, 2009, 11:04 AM:

My guess is that the lamp is getting old and worn out. I've got one that won't strike on low anymore - but it still strikes on high. I wouldn't worry about it until it stops striking on high.

Posted by Claus Harding (Member # 702) on August 26, 2009, 12:59 PM:

Kevin,
I get what you are saying, and Steven, I think your answer kind of ties into Kevin's in that if the lamp is getting 'up there' the high setting is helping it ignite better.
I will keep striking it on the high setting and as long as that goes cleanly, that is fine. If it starts doing the flicker on the high setting, I'll put in my new bulb.

Thanks for your help.

Claus.

Posted by Kevin Faulkner (Member # 6) on August 26, 2009, 05:03 PM:

I didnt realise the lamp was an old one. I think that as the lamp ages the gap between the electrodes increases due to the material slowly getting burnt away so yes they do need that extra voltage to keep the arc burning after it has been struck.

I'ts very dangerous to keep the igniter tripping over to try to get the lamp struck and running as it puts undue stress on the electronic components within the power supply and indeed this can lead to power supply failure in projectors such as the Elmo's especially the GS1200. If the lamp get very difficult to strike then the time has come to get it replaced.

Kev.

Posted by Claus Harding (Member # 702) on August 27, 2009, 01:10 AM:

Kevin,
The answer to that is that I don't know the age of the lamp, and neither did the seller.
I started using it, hoping for the best, and so far, it has performed without flickering during screenings. The start-up is the rough part now, on the low setting, but when I hit it on 'high' it comes on first strike, at least the last few times I did it.

I have a brand-new bulb from Superior Quartz, and if the one in the machine shows any reluctance firing 'high' it's time for it to go, and I am happy to have had the hours I had out of it.

A possible blown reflector (if it does indeed suddenly go) and cleaning the guts of the machine from minute glass splinters just is not worth the extra "value for the money." Nor is having to replace power supplies.

I appreciate the follow-up on this.

Claus.

Posted by John Whittle (Member # 22) on August 27, 2009, 10:44 AM:

I've never seen one of these small Xenon lamps exploding (and thank heavens since I don't know where you'd get a new reflector).

But as you probably know, the Xenon lamp operates on a low voltage high amperage DC, normally around 22/24 volts. To strike the lamp, a spark has to jump the electrodes causing the gas to excite and then the arc starts. It's the starts that cause the electrodes to wear and pit making starting harder over time. With the higher voltages, the lamp starts more reliabily.

In the machines that leave the lamp on and use a douser (the change-over versions of the Eiki 6000/6100 and the CX series Elmo and others) the lamp automatically starts on high and then drops to a standby voltage.

On the portables that strike the lamp just before showing, it can be a bit tedious to strike on high and drop to low, I'd suggest putting in a douser so that you can strike the lamp at first start and then drop the lamp before showing the first frame.

Normally we look at the number of strikes before the arc starts as a sign of lamp age. While I've never done this, I would think if you example the lamp (in place and off) with a good magnifier, you'll see pitting on the electrodes compared to your new lamp.

John

Posted by Claus Harding (Member # 702) on August 27, 2009, 01:03 PM:

John,
Thanks for that; I will keep in mind examining the bulb close-up if it comes to that.

The high/low thing is actually not a problem for me since I tend to run on high anyway; as discussed, it was merely the strike where I would set it to low thinking it would ease the load on the lamp, but since the lamp hits better on a 'high' start, I'll just leave it at that.

Claus.

Posted by Steven Sigel (Member # 21) on August 27, 2009, 01:27 PM:

I agree with John - I don't think there's a whole lot of danger of one of these small lamps exploding. What's happened to me with old lamps is they won't strike after several tries, or they'll strike, but lose the arc after running for a while. If on the other hand, it takes 4-5 tries to strike, but then runs fine, I would say that it's fine to keep using it until it gets much worse... I've got an EX-3500 and the lamp take several tries to strike (and wont strike on low power), but it's been like that for over a year...

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