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Author Topic: Xenex lamp problem Richard May Phenomenal Film Handler Posts: 1057 From: Floral Park, NY USA Registered: Aug 2004 posted 09-23-2009 09:45 PM                     I have a Xenex lamp with an Irem rectifier. They had an overheating issue over the summer. The lamp exhaust failed for about a week before they fixed it. I'm not 100% sure, but I think the problem happened right after that. Now it takes forever to light. I went there tonight to check it out. Turn the lamp switch on and it stikes instantly but will not light. I changed bulbs with a new one. Same thing. It's jumpimg the gap fine in the bulb. It doesn't seem to be arcing anywhere else. Keep turning it on and off. Same thing. Eventually it will light. The igniter sounds "normal". Does the igniter either "work" or not "work"? Could it be weak? Or does it sound like a rectifier issue? Once or twice tonight it lit on the first strike, but 99% of the time it took a few minutes.  |  IP: Logged Gordon McLeod Film God Posts: 9532 From: Toronto Ontario Canada Registered: Jun 99 posted 09-23-2009 10:42 PM                     Have you measured the noload voltage of the rectifier  |  IP: Logged Louis Bornwasser Film God Posts: 4441 From: prospect ky usa Registered: Mar 2005 posted 09-24-2009 04:29 PM                        Nothing to do with heat would hurt the rectifier. IF it is heat related. you may have a bad bulb or igniter, Try the spare (new) bulb first. (You do keep a new spare, don't you?) Louis  |  IP: Logged Richard May Phenomenal Film Handler Posts: 1057 From: Floral Park, NY USA Registered: Aug 2004 posted 09-26-2009 07:21 PM                     Tried a brand new bulb that night. It took about 20 tries to get it lit. It seemed like a nice strong zap but still took forever. I saw the arc across the electrodes and it looked fine. I'll check the no load voltage.  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 09-27-2009 08:31 AM                     Then verify the no-load DC voltage and if it's say at least 110 volts then the rectifier is probably ok. If it is low... around 85 to 90volts DC you may have an open diode or you may have a rectifier thats wound for 380 volts AC as many were up into the early 90s. If thats the case a booster box is in order and will mnake the lamp ignite on the first strike every time. Also check the insulator in the center of the mirror. If that insulator is alumnium you've found the problem as they like to conduct the high voltage right to ground, if it's the white teflon version then you're ok there and the ignitor is next in line to check. P.S. Louis... Heat is a semiconductors biggest enemy!! Its thermal cycling that kills the majority of diodes... power surges and lightning are next in line. Mark  |  IP: Logged Tim Reed Better Projection Pays Posts: 5246 From: Northampton, PA Registered: Sep 1999 posted 09-27-2009 08:54 AM                       He's talking about heat in the lamphouse. That affects the rectifier nil.  |  IP: Logged Gordon McLeod Film God Posts: 9532 From: Toronto Ontario Canada Registered: Jun 99 posted 09-27-2009 09:09 AM                     Tim i am also a little suspisius of the rectifier Kniesley has never been noted for their supression of HV and if it has been doing repeated multiple spikes I have seen the HV take out a diode Also be aware that the older IREMS had a much lower no load voltage around 85volts which was originally what OSRAM speced  |  IP: Logged Tim Reed Better Projection Pays Posts: 5246 From: Northampton, PA Registered: Sep 1999 posted 09-27-2009 09:22 AM                       Oh, I think it's entirely a rectifier problem - the RA relay in particular. I was referring to Louis' comment addressing the original post, which suggested the lamphouse heat might have affected the rectifier.  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 09-27-2009 01:08 PM                     quote: Gordon McLeod Also be aware that the older IREMS had a much lower no load voltage around 85volts which was originally what OSRAM speced Gord, No xenon lamp is going to reliably light on 85 volts DC!!! I was told by both the people at IREM (in an e-mail) and at Neumade(who manufactures the booster box)that the Irems made before about 1987 were wound for 380 volts three phase AC which is whats found in Europe and other contenents where the IREMs were the most popular. Irems manufactured after 1987 for export to North America were wound for 208 volts AC three phase and indeed they typically do about 120+ volts DC. John Walsh will also confirm this... I've bought qwuite a few boosters from him. The other very important item in Xenex-1's is that insulator in the center of the mirror. Has to be the teflon version as the anodize which insulated the alumnium versions has broken down over the years and no longer insulates correctly. Fire one in a dark room some time!!! Mark  |  IP: Logged Louis Bornwasser Film God Posts: 4441 From: prospect ky usa Registered: Mar 2005 posted 09-27-2009 08:33 PM                        Strange. . . the (dreaded) Osram bulbs work just fine at 85 volts. All of my pre 1985 IREM rectifiers are still in daily use and light just fine on the first try. Over 200 in use nearby; all with Osram. I have never installed a boost kit in my life, even with the 208 down to 190 volts. Louis  |  IP: Logged Gordon McLeod Film God Posts: 9532 From: Toronto Ontario Canada Registered: Jun 99 posted 09-27-2009 09:51 PM                     All IREMS sold in canada from day one were wound for 208 volts and had the standard 85 volt no load which was the spect no load voltage for many years Originally it wa by the way 65 volts which the early JOVY rectifers used  |  IP: Logged Tim Reed Better Projection Pays Posts: 5246 From: Northampton, PA Registered: Sep 1999 posted 09-27-2009 11:07 PM                       Same here.. no load is abt. 85VDC. I have several 1985-vintage XCN consoles still running as is. Although, they don't seem to like particular brand bulbs, they have been running fine on whatever Theatre Bulb Supply sends out. Osrams, too.  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 09-27-2009 11:37 PM                     I've seen many bulbs work just fine for the first few hundred hours life and ignition gets harder and harder the older the lamp gets. All of the problems I've experienced were with Irems on Xetron lamphouses of varying sizes and models. At any rate the booster solved the problem in every case. Even immediately lighting up lamps with many thousands of hours on them. I guess were there not a rectifier problem to begin with the booster wouldn't exist and all manufacturers would be building rectifiers with 85 volts no load instead of the typical 120 to 140 volts. Mark  |  IP: Logged John Hawkinson Film God Posts: 2273 From: Cambridge, MA, USA Registered: Feb 2002 posted 09-28-2009 12:47 AM                     Mark, we have some of those IREMs. (A pair of P1-X80s.) They are indeed intended for 220V (nameplate) operation, and while you can push them some, their components are certainly not rated for 380V (or even 280V), and you would be overvoltaging caps and transformers (and an 80V zener, I think...) and generally redlining components far beyond their design if you were to do so. (We've modified one by (1) Adding a variac/buck-boost in front to allow continuously variable current adjustment during operation (2) Adding two fans, which cool down the whole thing dramatically and makes me feel a lot better (3) Adding a boost circuit+cap+diode. We really need to finish the mods on the other one...) --jhawk  |  IP: Logged Monte L Fullmer Film God Posts: 8367 From: Nampa, Idaho, USA Registered: Nov 2004 posted 09-28-2009 02:28 AM                     Talking about boosting... I have a STRONG "suitcase" switcher which gives me over 140vdc on no load, but can't strike the bulb on the first pulse. Sometimes it takes a good 4 to 8 pulses to finally get the bulb to ignite..even on a new bulb (CXL-20R). I've even changed out igniters (DC type) and no change with this poor striking. Other consoles in this six-plex have no problems of igniting. Would a booster do justice for this, or just live with it? -Monte  |  IP: Logged

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