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Author Topic: Xenon Bulbs Exploding after about 1200 Hours Timothy Eiler Expert Film Handler Posts: 126 From: Litchfield , Minnesota, USA Registered: Mar 2000 posted 10-27-2003 12:34 PM                        I have seen a couple cases over the years where after an explosion The reflector directs light right back on the the bulb itself and causes overheating and premature failure.  |  IP: Logged John Pytlak Film God Posts: 9987 From: Rochester, NY 14650-1922 Registered: Jan 2000 posted 10-27-2003 12:42 PM                        quote: I have seen a couple cases over the years where after an explosion The reflector directs light right back on the the bulb itself and causes overheating and premature failure Are you sure the explosion caused the reflector to change? I suspect if the heat is being reflected back onto the lamp, the problem was there all along. The IR heat energy removed by the heat filter(s) does have to go somewhere. Be sure that a metal mirror with a dichroic coating is well cooled by sufficient airflow, and that any additional heat filters reflect the infrared energy to a well-cooled heat sink, and not back into the optical system.  |  IP: Logged Gordon McLeod Film God Posts: 9532 From: Toronto Ontario Canada Registered: Jun 99 posted 10-27-2003 01:06 PM                     In the older verticle lamphouses that had 2 reflectors it was possible to focus back on the lamp The rear reflector is an ellipitacl one so its second focus is past the apperture plate but the front one was spherical and it reflected back on the lamp all the energy that was projecting forward directly from the lamp and being wasted on the interior of the lamphouse The arc image was also inverted so it tended to smooth out the light field extensively It was important to focus the secondary inverted image to be just inside the arc gap to prevent the reflected image burning the electrod or a hole in the quartz  |  IP: Logged Timothy Eiler Expert Film Handler Posts: 126 From: Litchfield , Minnesota, USA Registered: Mar 2000 posted 10-27-2003 01:43 PM                        quote: Are you sure the explosion caused the reflector to change? As the reflector look perfect before the explosion and there several big dings in it afterwards I would say yes. Running the xetron Lamp with 2k bulbs for 3,000 to 3,200 (per company policy) for 7 years With no problems. Then one explodes. The next 3 bulbs only get 700-800 hours with visable overheating. New Reflector is install and there are no more problems  |  IP: Logged John Pytlak Film God Posts: 9987 From: Rochester, NY 14650-1922 Registered: Jan 2000 posted 10-27-2003 02:48 PM                        quote: Running the xetron Lamp with 2k bulbs for 3,000 to 3,200 (per company policy) for 7 years With no problems. Then one explodes. The next 3 bulbs only get 700-800 hours with visable overheating. New Reflector is install and there are no more problems Wow! Seems like a chance in a million that those "dings" would reshape the reflector to re-reflect the energy back to the lamp. Any chance the explosion did something else, like change the lamp mounts such that there was some physical stress being put on the lamp?  |  IP: Logged

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