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Author Topic: Spots developing on Osram bulbs Mark J. Marshall Film God Posts: 3188 From: New Castle, DE, USA Registered: Aug 2002 posted 03-14-2003 08:10 PM                    We're noticing a phenomenon here, and we're not sure what's causing it. We're running the Osram XBO HOFR 2K and 3K bulbs, and we're noticing small spots developing on the envelope, usually near the back end (the cathode?). We've called around to several other theaters in the area, and they're noticing it on some of their bulbs too. I'm not sure about the other theaters off hand, but we're using Strong consoles. At first we were thinking someone was touching them when they put them in, but that appears to not be the case. I did a forum search and found that we should order the "Technology & Applications" book from Osram. In the mean time, does anyone have anythin they can offer off the top of their head that may clue us in to what the problem is? Also, has anyone else noticed any spotting on Osram bulbs recently? Thanks!  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 03-14-2003 10:42 PM                     The best thing to do is to NOT use Osram lamps. They're no where near as good as they used to be.....Go with a brand name like Christie, LTI, or Superior Quartz. You'll have alot less trouble. Mark @ CLACO  |  IP: Logged Adam Martin I'm not even gonna point out the irony. Posts: 3686 From: Dallas, TX Registered: Nov 2000 posted 03-14-2003 10:55 PM                     What kind of spotting is it? A discoloration of the quartz, black residue, milky white or blue residue? That last one is from a gas leak. Can you post a photo?  |  IP: Logged Paul G. Thompson The Weenie Man Posts: 4718 From: Mount Vernon WA USA Registered: Nov 2000 posted 03-14-2003 10:59 PM                     Adam beat me to it. Post a picture. Maybe some of us can tell you what they are.  |  IP: Logged John Hawkinson Film God Posts: 2273 From: Cambridge, MA, USA Registered: Feb 2002 posted 03-14-2003 11:27 PM                     You don't need to order it, Osram's document Technology and Applications: XBO Theatre Lamps is up on their web site (linked to from the discharge lamps section). --jhawk  |  IP: Logged Larry Shaw Expert Film Handler Posts: 238 From: Boston, MA, USA Registered: Mar 2000 posted 03-15-2003 04:50 PM                        Mark, I have a couple bulbs that look like this: Is this the same damage you're getting?  |  IP: Logged Michael Schaffer "Where is the Boardwalk Hotel?" Posts: 4143 From: Boston, MA Registered: Apr 2002 posted 03-16-2003 07:08 AM                        That lamp is obviously overheated. Probably from bad electrode connections.  |  IP: Logged Rick Long Jedi Master Film Handler Posts: 759 From: Toronto, Ontario, Canada Registered: Nov 1999 posted 03-16-2003 08:48 AM                     I too, have noticed similar discoloration on some of our bulbs. Mark, which Strong Console Model is this?  |  IP: Logged Tim Reed Better Projection Pays Posts: 5246 From: Northampton, PA Registered: Sep 1999 posted 03-16-2003 01:00 PM                       I used to get that, too, years ago at a particular theatre. Never did figure out what it was. Just concluded it must have been the Osrams, since they began to fail more than Christies did.  |  IP: Logged Paul G. Thompson The Weenie Man Posts: 4718 From: Mount Vernon WA USA Registered: Nov 2000 posted 03-16-2003 01:05 PM                     I think it is defective manufacturing and quality control. If you recall correctly, the metal ends of the xenon bulbs are designed to turn yellow if the temperature parameters are exceeded. I forgot what the figure was, but as far as I know, it is still being done that way by bulb manufacturers. Larry, that looks like a "High Milage" bulb, and by looking at the anode, it might have been driven too hard. Is there a possibility some crud and corruption may be falling out of a dirty stack onto the bulb and burning its way into the envelope? Just a thought...  |  IP: Logged Rick Long Jedi Master Film Handler Posts: 759 From: Toronto, Ontario, Canada Registered: Nov 1999 posted 03-16-2003 11:14 PM                     The reason that I asked about the type of Strong console being used, has to do with our experience at a couple of theatres using used equipment. The older Highlight models brought air in through a relatively small fan at the back of the lamp and used it to cool the ends of the lamp. Mind you, these lamps were designed for a 3K maximum not for the higher watage bulbs that we were forced to put in them. The Highlight II, on the other hand, uses a large fan forcing plenty of booth air into the "dog-house" behind the reflector. This has two advantages; the reflector is cooled by the heat-sinking effect of the pressurized air (pointed out by John Pytlak in another post) and the air rushing through the hole in the reflector around the bulb. This air with a horizontal forward vector, meets the heat being reflected from the perpindicular heat filter. Fans, mounted at the front of the lamp and blowing up, just in front of the bulb, combine to send this hot air up the stack (which by the way, is much better placed than the one on the older Highlight). During the X-90 phase of Strong's manufacturing, it appears that they elected to use the same philosophy in these lamps as well, at least in later phases of manufacturing. Earlier X-90's did not have the dog-house behind the reflector that the later ones did. On my next service visits, I will pay attention to see if there is any relationship between lamphouse design and the discoloration Mark mentioned.  |  IP: Logged Robert Golding Film Handler Posts: 65 From: Sutter, CA, USA Registered: Jan 2001 posted 03-17-2003 03:11 AM                     I've had this problem with Osrams. I use to run 4k bulbs years ago and had this problem start at around 900 hrs. It's caused by overheating or in my case a bad ground to the lamphouse. I've since stopped using osrams and will only use Christie's. They haven't given me a problem for over 10 years.  |  IP: Logged Mark J. Marshall Film God Posts: 3188 From: New Castle, DE, USA Registered: Aug 2002 posted 03-17-2003 09:17 AM                    Wow. Once again, I ask a question and go away for two days only to find tons of responses! Thanks for the help guys. To answer a few of the questions posed here... quote: What kind of spotting is it? It's a milky white sometimes speckled spotting usually about the size of a small fingerprint (which is what we originally thought it was until we took extreme measures to ensure no one was touching them - only to have the spots show up anyway). Our engineer noticed that the spots are actually on the INSIDE of the envelope under the Cathode (not sure how I missed that before). The best way I can describe it is to quote our engineer: "It looks like a drop of milk fell off the back of the cathode and landed inside the quartz envelope." quote: Can you post a photo? Good idea... I'm working on that. I'll get back to you. quote: which Strong Console Model is this? I'll be at the theater tonight, and I can give you an exact model number. Off the top of my head, they are Strong Super Highlights, and they're about 12 years old. I'm not sure about the other theaters that our manager called, but I'll find out. Thanks again! Mark  |  IP: Logged John Pytlak Film God Posts: 9987 From: Rochester, NY 14650-1922 Registered: Jan 2000 posted 03-17-2003 10:48 AM                        Either something is subliming and depositing itself on the inside of the quartz envelope, or it is a type of vitrification (recrystalization) of the quartz. In either case, it looks like the lamp will be more prone to catastrophic failure.  |  IP: Logged Tim Reed Better Projection Pays Posts: 5246 From: Northampton, PA Registered: Sep 1999 posted 03-17-2003 11:43 AM                       Yes, any dark spots on the envelope also conduct more heat. It's a chain-reaction.  |  IP: Logged

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