Film-Tech Forum ARCHIVE: Lamphouse "welds" thru its negative lead

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Posted by Kenny Thies (Member # 1551) on 05-08-2005, 09:04 AM:

Hello all,

Last night during a late show of Amityville Horror, a person comes out and says that the "video" is no longer visable on the screen. Lucking I was still in the building and was able to move the remainder of the print to an open house and show the rest of the movie.

After we closed, I thought that it was just a bad bulb and went to replace it and when I opened the lamphouse up (CFS 2000) I noticed that the negative lead wire from the rectifier to the base of the bulb was just dangling in the wind. Upon further inspection, I noticed that the remainder of the wire in the connector on the rectifier was completely "welded" inside the connector. Luckily I had an old rectifier we use for parts and I was able to get the same connector to replaced the welded one. I also stripped back part of the wire that goes to the bulb to get a clean wire. I put it all back together and now it works.

My question is... was this caused by the bolt not being tight enough on that connection to cause it to have resistance and build up heat, creating the weld? Or should I be looking for something else? Everything else looked fine. I inspected all other connections and they were tight. This lamphouse has 14,000 hours on it, and is the first problem we have had with it.

Thanks for the input.

Kenny Thies

Posted by Mark Gulbrandsen (Member # 72) on 05-08-2005, 10:30 AM:

quote: Kenny Thies
Or should I be looking for something else?

This is not uncommon on these lamphouses. I've geard of this happenning several times from our customers that choose to drive the dam things. Just be sure that all the bolts are tightened. This should be done once a year or when you change your lamp which seems to be once a year in many locations.

Should you be looking for something else? Absolutely YES! Replace that CFS pos with something that is better built and more efficient at getting the light from the arc to the screen. The cfs's were always light wasters......

Mark

Posted by Monte L Fullmer (Member # 2797) on 05-08-2005, 04:38 PM:

Mark, did the ORC consoles have the same basic problem being that basement loaded vertical mounted bulb setup? (gut getting better?)

I'll get the focal length on that lens, we may do the loaner thing from you.

thx-Monte

Posted by Aaron Sisemore (Member # 145) on 05-09-2005, 12:41 AM:

I have had the same happen on three CFS rectifiers and one early Christie.

I strongly recommend replacing the entire negative cable rather than using the overheated cable, as even though it appears clean and shiny, it will have enough oxidation within it to potentially cause another 'meltdown' again.

-Aaron