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Author Topic: Burning aperture plate Rob van Ede Film Handler Posts: 25 From: Zeist, The Netherlands Registered: Sep 2002 posted 07-11-2003 10:18 AM                        Hi, about a week ago, one of our projectors started getting real hot around the gate. First, the aperture plate was blackened a bit, but it's getting worse: now the plates are getting so hot that pieces come off and the little window on the side got so hot that it cracked. The first plate is almost "burned up", so to say. The strange thing here is that there was nothing changed on this projector, light output on the screen is good and the light falling on the shutter seems to have no hot spots either. I realize that this is quite a problem and hope that the tech will come very soon as i don't know how to solve this and of course this is happening on our largest screen. What could be the cause for a problem like this that starts so suddenly? Projector: Ernemann 15 Lamphouse: Xenosol 2000 Lamp: Osram 2K Thanks, Rob  |  IP: Logged Ken Layton Phenomenal Film Handler Posts: 1452 From: Olympia, Wash. USA Registered: Sep 1999 posted 07-11-2003 10:29 AM                     Is there a heat filter on your lamphouse?  |  IP: Logged John Spooner Expert Film Handler Posts: 186 From: South Australia, Australia Registered: Jan 2003 posted 07-11-2003 11:18 AM                     Dear Rob and Ken. I also would tend to suspect the heat filter as these types of lamps use a glass mirror and a dichroic heat filter of Jena glass mounted at an angle just before the dowser. If the glass filter has broken or is missing, then the aperture will receive too much heat as you are experiencing. At the very least, reduce your lamp current to as low as practically possible until your tech arrives. John Spooner. South Australia.  |  IP: Logged Aaron Sisemore Flaming Ribs beat Reeses Peanut Butter Cups any day! Posts: 3061 From: Rockwall TX USA Registered: Sep 1999 posted 07-11-2003 11:59 AM                     Not being familiar with the Ernemann 15, I cannot know for sure... Is the gate liquid cooled? If so, has your cooling circulator failed or coolant level become low? You may also want to check the exhaust fan as well- you would be suprised how much heat they actually take away from the lamp and projector gate. -Aaron  |  IP: Logged Rob van Ede Film Handler Posts: 25 From: Zeist, The Netherlands Registered: Sep 2002 posted 07-11-2003 12:48 PM                        The projector used to have a heat filter in front of the douser. Last year it fell off and our tech assured the manager that this was no problem, so the machine now runs for about a year without heat filter. There have been no problems until last week, when this heat issue started. I must add that about a month ago, a new bulb was fitted (not by me). For tree weeks after that, there were no problems. This afternoon, i talked to the tech (who is on holiday at the moment ), and now he wants me to put the heat filter back in. Never done such a thing but i have to try, there's no backup so i'm pretty much on my own. Yesterday i already lowered the current by about 5 A an it didn't really help. The problem is that crappy, uncalibrated current meter on the lamphouse: it tells nothing, so i don't know what i'm doing and i hate that. I now have a current measuring device to put over a cable (don't know the English word) but i have no idea on what cable i should measure. It should carry a one-way current according to the manual. Any suggestions? The gate is not water cooled, and air intake is working (new air filter last week, so that shouldn't be a problem). Thanks, Rob  |  IP: Logged John Hawkinson Film God Posts: 2273 From: Cambridge, MA, USA Registered: Feb 2002 posted 07-11-2003 01:39 PM                     Rob, the current going in to the lamp should be the same as the current going out, so it shouldn't matter which cable you measure. Just make sure you have a clamp ammeter that can measure DC current, not just AC. --jhawk  |  IP: Logged Rob van Ede Film Handler Posts: 25 From: Zeist, The Netherlands Registered: Sep 2002 posted 07-11-2003 06:34 PM                        update: i've managed to stop the burning by placing a blower very close to the gate, generating a lot of airflow. This way, there are no longer (strong) signs of burning on the aperture plate after a show. Will be able to keep the machine running till our tech is back in a few days. I'm still wondering what might have caused this sudden temperature increase... Rob  |  IP: Logged Bill Carter Expert Film Handler Posts: 162 From: Minneapolis, Minnesota Registered: Sep 1999 posted 07-11-2003 09:04 PM                     My first guess would still be that something has changed in your exhaust system.  |  IP: Logged Gordon McLeod Film God Posts: 9532 From: Toronto Ontario Canada Registered: Jun 99 posted 07-11-2003 09:10 PM                     On the back of many 15's is a pancake mufin fan check to see it is working it cools the shutter box  |  IP: Logged John Pytlak Film God Posts: 9987 From: Rochester, NY 14650-1922 Registered: Jan 2000 posted 07-11-2003 10:10 PM                        If you are burning the aperture plate, it's very likely you also have so much heat that you are damaging your prints: http://www.kodak.com/US/en/motion/newsletters/pytlak/fall97.shtml http://www.kodak.com/US/en/motion/newsletters/pytlak/winter97.shtml A dichroic heat filter (or "cold" mirror) is usually required for power levels above 2000 watts. Since this just started happening and the heat filter has been gone for quite a while, I suspect the lamp alignment/focus has changed, or you are overpowering the lamp.  |  IP: Logged Jason Burroughs Jedi Master Film Handler Posts: 654 From: Allen, TX Registered: Jun 99 posted 07-12-2003 01:00 AM                     I too think it could be a malfunction of the exhaust system. Lack of proper exhaust will not only shorten bulb life, but result in a very hot projector, as well as a hot booth.  |  IP: Logged Rob van Ede Film Handler Posts: 25 From: Zeist, The Netherlands Registered: Sep 2002 posted 07-12-2003 04:13 AM                        The day after the small green glass broke, i ran a loop of 5 m trough the projector for 20 minutes and the image looked the same all the time. Upon inspection of the film afterwards, there was a very light "deformation" visible in every frame, no signs of color change though. I guess that with the extra fan and the lowered lamp current, i'm at the safe side (well, i hope). Gordon, where exactly should i look for that pancake mufin fan? I know of two fans: one intake on the back of the lamphouse and one on top of the lamphouse for exhaust. Rob  |  IP: Logged John Walsh Film God Posts: 2490 From: Connecticut, USA, Earth, Milky Way Registered: Oct 1999 posted 07-12-2003 09:45 AM                     This is the fan on the front: This is the fan in the back: Like several other things on an Ernamann 15, it looks like their engineers took all of 10 min. to design in the cooling system. There is no water cooling option avaiable for this projector.  |  IP: Logged Rob van Ede Film Handler Posts: 25 From: Zeist, The Netherlands Registered: Sep 2002 posted 07-12-2003 10:08 AM                        John, thanks for the photos. We don't have the fan in front, just some passive cooling over there. I've now run three shows with a large table fan next to the projector and without burning anything. I'll post what the cause for this al was when it's sorted out, i hope later this week. Rob  |  IP: Logged Gordon McLeod Film God Posts: 9532 From: Toronto Ontario Canada Registered: Jun 99 posted 07-12-2003 06:29 PM                     I have several 15's with both fans running on xetron consoles with 6k lamps and they stay nice and cool Also the ernaman lamphouse has a cold light reflector (same as te kinoton) so the light shoul be fairly cold to start with  |  IP: Logged

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