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Author Topic: Re-striking a xenon bulb Ken Lackner Phenomenal Film Handler Posts: 1907 From: Atlanta, GA, USA Registered: Sep 2001 posted 11-21-2003 02:58 AM                     It is my understanding that a xenon bulb can strike at any state of cooling, that once it goes out you do not have to wait for it to cool down before you can strike it again. We had a show stop for a moment today and when we started it again the bulb would not strike. We had to wait nearly five minutes before we could strike it again. What could cause this? It is a Xenex II lamphouse with a Kni-Tron power supply. We use a mix of Christie and Osram. Not sure which one is in this house.  |  IP: Logged Howard Johnson Film Handler Posts: 87 From: Felpham , West Sussex, UK Registered: Jun 99 posted 11-21-2003 04:25 AM                     I tend to leave the xenon on unless there is a break of an hour. Every time you strike them it puts the eqivalent of perhaps 15 mins time on them - I'm not sure of exact time. I've found that different lamphouses vary in whether they will be difficult to restart after a short interval. It's easier to leave them on!  |  IP: Logged Chris Greenwell Film Handler Posts: 28 From: West Valley, Ut Registered: Mar 2003 posted 11-21-2003 04:31 AM                     I had a power bump a few days ago, just enough to stop the machines. My older bulbs had a hell of a time striking back on, but the new ones striked right back up.  |  IP: Logged Joe Beres Jedi Master Film Handler Posts: 606 From: Minneapolis, MN, USA Registered: Nov 2000 posted 11-21-2003 08:24 AM                     I too have found striking, and especially re-striking a warm lamp, more difficult with an older lamps. Does it take a while for the initial strike at the beginning of the day? How many hours on the lamp?  |  IP: Logged Antonio Marcheselli Phenomenal Film Handler Posts: 1260 From: Florence, Italy Registered: Mar 2000 posted 11-21-2003 08:34 AM                        I worked in a theater that had many problems striking hot lamps. But the lamphouse had definively some problems since all the time the 4000 lamp was black after 4/500 hours. Bye A  |  IP: Logged Jeff Taylor Jedi Master Film Handler Posts: 601 From: Chatham, NJ/East Hampton, NY Registered: Apr 2000 posted 11-21-2003 09:06 AM                     In theory a xenon lamp will re-strike at any temperature, but hot re-strikes are more challenging than cold strikes. There are several reasons for this, but the main one is that xenons are tougher to strike as the pressure inside the lamp increases. Different manufacturers pressurize their lamps to different levels at the factory to begin with, and there is a correlation between pressure and the quality of light output. Similarly, the hotter the lamp is the higher the pressure, which can lead to the hot re-striking problem. Also, as the hours pile up on a xenon lamp the electrodes naturally wear causing the gap to increase and making striking more difficult. Then there's the whole issue of ignitor voltage and run amperage which can cause more problems. If everything is running up to spec and your lamp is relatively new you should be able to re-strike hot, but it's not surprising that in a real world situation you might have problems, or at least have to zap it a few times to get a strike while hot.  |  IP: Logged Darryl Spicer Film God Posts: 3250 From: Lexington, KY, USA Registered: Dec 2000 posted 11-21-2003 09:07 AM                    I used to work with Xenex II lamphouses year ago. This was a common problem with those. What they did was change the igniter to one that was used in a stong lamphouse. Problem never occured again.  |  IP: Logged Ian Price Phenomenal Film Handler Posts: 1714 From: Denver, CO Registered: Jun 99 posted 11-21-2003 11:41 AM                     We had a problem re-striking a hot lamp in our big house. It has a Strong Highlight, switching power supply and a Christie lamp. Since I have worked in many theatres with many size lamps, I knew that it was not the lamp. Indeed, eventually the power supply failed and was replaced. Now there is no problem, ergo it may be a power supply problem.  |  IP: Logged Daryl C. W. O'Shea Film God Posts: 3977 From: Midland Ontario Canada (where Panavision & IMAX lenses come from) Registered: Jun 2002 posted 11-21-2003 11:55 AM                        Power supplies with lower no-load voltages will have problems starting hot lamps.  |  IP: Logged Ken Lackner Phenomenal Film Handler Posts: 1907 From: Atlanta, GA, USA Registered: Sep 2001 posted 11-21-2003 02:02 PM                     No we do not have any problems with a cold strike in this house. Not sure how many hours are on the bulb, but it's a safe bet that it needs replacing. And if the show has stopped because the automation stopped it, the bulb will go out. No way to keep it on.  |  IP: Logged Travis Hubrig Expert Film Handler Posts: 175 From: Minot ND, USA Registered: May 2003 posted 11-21-2003 09:18 PM                     I run 7 Xetron XHN's, never had a problem with a hot bulb striking. I run Osram 1600 w bulbs and the few problems I encounter are due to improper cooling.  |  IP: Logged Brad Miller Administrator Posts: 17775 From: Plano, TX (36.2 miles NW of Rockwall) Registered: May 99 posted 11-21-2003 09:26 PM                     I'm curious as to what kind of lamps most of you with problems are using and what kind of systems you are using them in. For instance, you can sit there all day long at 5 second intervals and fire / extinguish / fire / extinguish / fire / extinguish a Christie lamp in an SLC style Christie console (not the older ones though). The same thing can be said for a Christie lamp in a Strong lamphouse with a switcher power supply (at least my 2K units can), and I've never had a glitch from a Christie lamp in a Cinemeccanica lamphouse with Irem supply either. The only time I have ever had issues like this is with high reactance Strong supplies and non-Christie lamps. BTW, a tip I picked up awhile back that does work nicely. If you have a bulb past it's warranty hours and it is having issues striking and you do not have a spare handy for replacement, up the tap settings one notch for one show, then put them back. I've had lamps run another 3 months without a hint of problem after doing that. (Disclaimer - check with your service tech before doing this. It is ultimately his/her decision.)  |  IP: Logged Dave Callaghan Film Handler Posts: 60 From: Toronto, Ontario, Canada Registered: Jan 2003 posted 11-21-2003 09:48 PM                     According to an OSRAM publication, increasing the current is discussed in connection with bulb rotation. After a rotation, OSRAM suggests operating the bulb at its current control range maximum to re-establish the arc root at the cathode tip to reduce arc instability / flicker. When a horizontal bulb has just been rotated, OSRAM recommends operating the lamp for 30 minutes to 2 hours at the permitted maximum current to reform the cathode root.  |  IP: Logged Travis Hubrig Expert Film Handler Posts: 175 From: Minot ND, USA Registered: May 2003 posted 11-21-2003 10:09 PM                     I have been told, and maybe have read it here, that bulb rotation in a horizontal installation isn't necessary anymore. The material and technology in the bulb is getting better and the deposit on the quartz isn't nearly as bad as it used to be. Most of my bulbs never get rotated.  |  IP: Logged John Pytlak Film God Posts: 9987 From: Rochester, NY 14650-1922 Registered: Jan 2000 posted 11-21-2003 10:12 PM                        Lamp rotation should be per the lamp manufacturer's recommendation.  |  IP: Logged

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