Film-Tech Forum ARCHIVE: Kelmar changeover sticking

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Posted by Joe Beres (Member # 678) on 09-04-2003, 05:03 PM:

I have a changeover booth with a pair of Century/Westar SA projectors with Kelmar changeovers. The changeover on the right projector is sticking periodically, but only when opening. It's happened twice during shows, but I can't figure out why. I can't seem to get it to happen consistently.

If I disconnect the shutter from the changeover, I can not get it to stick at all, so that would lead me to believe that it is a physical problem happening when the shutter is sliding upward in the casting. I have checked the shutter for any inconsistencies, and did not find any. I even gave the edges a light filing incase there were burrs or something else imperceptible. The shutter seems to sit in the track of the casting somewhat loosely, so I don't think it is binding in there. The casting that the shutter slides into sits somewhat loosely in the projector, but I can't seem to get it to stick consistently by holding it in any particular position. (Can this casting mount be tightened at all?) The tracks are free of debris. The steel wire that connects the shutter to the changeover seems to have a good amount of play. I have run out of places to look. Any more ideas? Please help.

Posted by Matthew Bailey (Member # 601) on 09-04-2003, 07:18 PM:

Maybe if can take the changeover solenoid off the proj. & disassemble it. There is a possibility there is some crud on the inside diameter of the coil spools & the solenoid plungers that fit inside them that can be removed with FG or alcohol.

Posted by Bill Carter (Member # 156) on 09-04-2003, 07:29 PM:

Joe,

When you say it only happens "during shows", do you mean a couple of reels in, after everything is nice and hot? Could the sticking be heat related?

Posted by Gordon McLeod (Member # 33) on 09-04-2003, 07:34 PM:

There is a leaf spring that pushes against the linkage rod in the changeover and locks the unit in the open close by snapping over a cap screw
I have had that spring bing and I usually just bend it out a very small amount
Also I have had the linkage rub against the top cover

Posted by Joe Beres (Member # 678) on 09-04-2003, 07:43 PM:

Thanks for the responses.

Bill, it's happened twice during a show, but I was able to get a failure today, when everything was fairly cool.

Posted by Mark Gulbrandsen (Member # 72) on 09-04-2003, 08:23 PM:

There are actually two springs in there. Be sure they are of equal tension and that all fastning screws are tight. If all looks well tear it down and clean everything up and re-assemble it. Should work ok then.
Mark @ Claco

Posted by Brad Miller (Member # 2) on 09-04-2003, 10:27 PM:

Joe, check the material your douser blade itself is made of. I have seen substitute douser plates that would slightly melt from the heat of the lamp from the xenon bulb. All it would take is several seconds in some cases to melt the blade just enough so that it would temporarily warp enough to cause the changeover to stick. It would always work fine at the end of the reel because it was out of the way of the heat.

Posted by Rick Long (Member # 213) on 09-04-2003, 11:33 PM:

I have had to file the edges of the cap screws that Gord mentioned to allow them to slide under the springs. Just create a small "ramp" for them to slide so's they dont bind against the springs.

Posted by Darryl Spicer (Member # 711) on 09-05-2003, 02:19 AM:

Also check the two screws that hold the coupler to the shaft mechanism. This part is tied into the selenoid pistons. I have had those screws become loose causing the unit to stick or not want to open.

Posted by Joe Beres (Member # 678) on 09-10-2003, 02:46 PM:

Well, once again, the Film-Tech members have saved the day. I opened up both changeover units, and both looked fine, but I cleaned everything up with a little alcohol, and wiped a bit of silicone lubricant on the moving parts, and voila, all is well again. Thanks for all of your help. [Big Grin]