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Author Topic: Xenon Bulb wire Daniel W. Skeen Film Handler Posts: 6 From: Yelm, Washington, usa Registered: Apr 2007 posted 09-06-2007 10:19 PM                        What is the purpose of the small "shorting" wire on Xenon bulbs? It goes from anode to cathode, across the glass bulb. Should it be left on or removed when the bulb is installed?  |  IP: Logged Monte L Fullmer Film God Posts: 8367 From: Nampa, Idaho, USA Registered: Nov 2004 posted 09-07-2007 12:14 AM                     That wire aids in ignition since it acts like a small capacitor to get the spark across the electrodes inside. Ususally it's best to leave that wire on if necessary. It can be taken off, but bulb ignition might be harder to accomplish.  |  IP: Logged John Walsh Film God Posts: 2490 From: Connecticut, USA, Earth, Milky Way Registered: Oct 1999 posted 09-07-2007 07:40 AM                     Yes, you should leave it on; as Monte said, it helps with ignition. It actually does not connect anode to cathode, it just connects at one end. If it connected, it would short out the power supply! It's made of nichrome, not regular copper since copper would burn up quickly.  |  IP: Logged Stephen Furley Film God Posts: 3059 From: Coulsdon, Croydon, England Registered: May 2002 posted 09-07-2007 08:04 AM                     A similar ignition aid is also used on some less exotic lamp types. Some Philips lamps have printed onto the outside of the arc tube a ring at each end, with a thin line along one side, jioning the two rings. I first saw it on SDW-T 'White SON' lamps, a lamp type never common in America, and tending to be replaced here in Europe by compact ceramic metal halide now. These lamps operate at a higher pressure than normal SON lamps, and the use of this device enables them to strike with a lower ignition Voltage than would otherwise be the case. They're suposed to be used with special control gear, but I can just about get one to strike with a 2.3kV SON ignitor. Philips now use this device on regular SON lamps as well. They've started using a higher proportion of xenon in the buffer gas fill, which would otherwise raise the ignition Voltage needed. There's a pucture of it here  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 09-07-2007 08:45 AM                     quote: Monte L Fullmer That wire aids in ignition since it acts like a small capacitor to get the spark across the electrodes inside. Monte... Its not a capacitor! All it does is aid in ionizing the xenon gas within the bulb to insure good ignition. The wire needs to be there and if is damaged can usually be replaced with wire that can be had from any one of the lamp manufacturers. Mark  |  IP: Logged Louis Bornwasser Film God Posts: 4441 From: prospect ky usa Registered: Mar 2005 posted 09-07-2007 10:52 AM                        The exception is the XeLamp by LP Associates. The wire MUST BE removed if the bulb is to ignite in the operating position. Louis (It arcs over to the reflector.)  |  IP: Logged Dan Reiter Film Handler Posts: 74 From: Easton PA Registered: Jul 2002 posted 09-07-2007 12:35 PM                     Also to help de-mystify: The ignition wire is usually connected to the positive end of the lamp via the end fitting, ties in a loop around the lamp body just before the envelope, travels over the envelope, and ends in another loop on the other end of the envelope. This provides a positive charge to help the arc jump from Cathode to Anode during ignition, as the igniter is usually connected in series on the negative end of the lamp. As all have said before, an ignition aid. Louis did bring up one note. If the opening of the reflector where the lamp goes through is small, and close to the lamp body, there is the possibility of ignition arc-over on a hard-striking lamp via the ignition wire. That, in addition to restricted cooling air flow, will shorten lamp life.  |  IP: Logged Monte L Fullmer Film God Posts: 8367 From: Nampa, Idaho, USA Registered: Nov 2004 posted 09-07-2007 01:36 PM                     quote: Dan Reiter as the igniter is usually connected in series on the negative end of the lamp. ..which brings up the interesting question on this one: What about the positive connected ignitors like the Christie lamphouses and consoles? Granted, this action still does work well with these consoles, but still interesting to hear on this one.  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 09-07-2007 06:55 PM                     quote: Dan Reiter Louis did bring up one note. If the opening of the reflector where the lamp goes through is small, and close to the lamp body, there is the possibility of ignition arc-over on a hard-striking lamp via the ignition wire. That, in addition to restricted cooling air flow, will shorten lamp life. There are quite a few XeLamps on my service routes and I've found that the use of a lamp with an oval shaped glass envelope(Ushio,Christie) eliminates the problem of arc over to the XeLamp reflector. Mark  |  IP: Logged Gordon McLeod Film God Posts: 9532 From: Toronto Ontario Canada Registered: Jun 99 posted 09-07-2007 09:35 PM                     The older Zeneith 2000H and 3000H had some issues with the nichrome wire  |  IP: Logged Bryan M. Montgomery Film Handler Posts: 47 From: Chillicothe, Ohio Registered: Jul 2007 posted 09-08-2007 01:00 AM                        We had to remove the ignition wire on bulbs used in our Zeniths years ago, otherwise they would not strike.  |  IP: Logged Tim Reed Better Projection Pays Posts: 5246 From: Northampton, PA Registered: Sep 1999 posted 09-08-2007 01:32 PM                       The Cinemeccanicas were notorious for that.  |  IP: Logged Michael Schaffer "Where is the Boardwalk Hotel?" Posts: 4143 From: Boston, MA Registered: Apr 2002 posted 09-08-2007 05:21 PM                        quote: Dan Reiter This provides a positive charge to help the arc jump from Cathode to Anode during ignition How? I can see how the wire "relocates" the positively charged portions of the lamp closer to the anode, but on the outside of the bulb. How exactly does this aid the discharge across the arc gap inside?  |  IP: Logged Louis Bornwasser Film God Posts: 4441 From: prospect ky usa Registered: Mar 2005 posted 09-08-2007 05:27 PM                        This is a "gimmick" capacitor. Louis  |  IP: Logged Gordon McLeod Film God Posts: 9532 From: Toronto Ontario Canada Registered: Jun 99 posted 09-08-2007 07:26 PM                     Kneisley used to have a small beaded chain that one hung on the lamp to help do the same  |  IP: Logged

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