Film-Tech Forum ARCHIVE: Christie H20 bulb arcing

This is topic Christie H20 bulb arcing in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Richard May (Member # 2627) on 04-05-2010, 10:00 PM:

Not sure if I have a bulb issue or lamphouse issue here. The projectionist changed the bulb because of age and ongoing flicker. Right away he had trouble lighting the new bulb. It would light after a few strikes, but was kind of hard striking. He then told me that when he put the new bulb in, he put the front clamp on too close to the screw the holds the glass cooling tube in place and it welded to it upon ignition. He broke it off and repositioned the clamp and lit the bulb. It was from THAT POINT ON that he had hard striking. I went down and checked it out. Whats happening is the bulb will light sometimes right away. Other times, it arcs across the electrodes, then from the ignition wire to the reflector. All cables are tight. I didn't have another bulb to try. Could the initial short from the clamp have damaged the bulb? He said there was never a problem before this?

Posted by Gordon McLeod (Member # 33) on 04-06-2010, 12:36 AM:

You may need to remove the small nichrome wire across the lamp

Posted by Monte L Fullmer (Member # 2797) on 04-06-2010, 01:05 AM:

Yea, those old CH20 consoles were known for this due to the high elliptical curve of the reflector where the bulb sits so far back into it that the nichrome wire arcs across the inner rim of the reflector.