Film-Tech Forum ARCHIVE: Picture shakes left to right, Christie pw35

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Posted by Michael J. Barr (Member # 976) on 01-09-2002, 03:08 AM:

The picture is shaking left to right but in like a little bit of a rythem. It's like two quick shakes for a second and then it skakes just a little for a second. It just repeats this from when it starts to when it stops.

Posted by Brad Miller (Member # 2) on 01-09-2002, 03:17 AM:

Your lateral guide rollers are most probably out of alignment. First thing, remove the gate and make sure the inboard side of both guide rollers snap back into place as you pull them apart.

By the way, does this happen on all prints, or just some?

Posted by Michael J. Barr (Member # 976) on 01-09-2002, 03:27 AM:

My lateral guides are oiled and work fine, how would I check the alignment. Also, my proj. are p35gps, I just forgot for a min.

Posted by Michael J. Barr (Member # 976) on 01-09-2002, 03:30 AM:

Sorry Brad, it shakes on all prints.

Posted by Brad Miller (Member # 2) on 01-09-2002, 04:39 AM:

First thing I would do is swap gates with another projector and verify the problem follows the gate. I am 99% sure it will. (All you will need to do is run a trailer through each projector to verify this.) Assuming the problem follows the gate, read on.

Christie sells a little tool to align those properly. However in a pinch you can get a somewhat decent alignment by aligning them against the trap rails. Note this is NOT the recommended way of aligning these (you really need that alignment tool), but it sounds like you are in a bit of an emergency situation and this definitely helps. Let me describe this from memory as best I can in the simplest way possible.

Remove the gate assembly from the projector.

Close the trap. Do both rollers spin freely? Odds are one of them is hitting up against the rails or is too far outward toward the operator (usually the top one). Take an allen wrench and insert it into the inboard side of the gate and turn counter clockwise (loosening) the set screw of one of the lateral guide rollers. Do NOT loosen it more than about 1 turn! If you do so, the tiny ball jewel could fall out and you will suddenly have a BIG problem.

Note: each lateral guide roller allen screw adjustment has a locking allen screw. You will have to loosen this just a tad (maybe 1/4 turn) in order to be able to freely tighten/loosen the adjustment.

Now turn the allen wrench on the outboard side clockwise (inward) so that you are in essence moving the entire lateral guide roller (the stationary side) up against the rails. Note you will only be able to do this for about one turn, because that is all you loosened the other side. Now go back to the inboard side and loosen it another turn and repeat on the outboard side by turning it inward another turn. You want to do this until the lateral guide roller freezes up against the trap rails and can no longer spin freely. Now loosen the outboard side exactly 1/4 of a turn and lock it back down with the locking allen screw. At this point, tighten the inboard side allen screw so that you freeze up the spinning of the lateral guide roller, then back of 1/4 turn (or the minimum required to allow the roller to spin freely) and lock that adjustment down. Repeat for the other lateral guide roller.

Basically this trick utilizes the trap rails as a guide for adjusting the lateral guide rollers. The biggest downside to this is that your picture may no longer be exactly centered after doing this (assuming it was centered in the first place). Note this will not affect the aperture alignment, but may alter the film position on screen slightly. (Green bands may appear off center just a tad.) If it is off bad enough that you can see the edge of the picture (doubtful), you can cheat a bit by loosening the outboard side of both lateral guide roller adjustments 1/4 turn at a time (don't forget to re-adjust the inboard side if you do this) until the picture is back centered, but remember there comes a point where if you back it off too far that the inboard side can no longer *snap* back up against the film because it will be riding on the trap rails. Still, this will get you through an emergency until your tech can come with the proper tool.

Before I finish, I am going to say this one more time...be careful when you loosen the allen set screws!!! If you loosen them more than 1 turn at a time you WILL lose those tiny ball jewels and your gate will be useless! If you are not 100% understanding of this procedure, do not do it! I can try to get some pictures of how to do this if you need, but there are some explosion diagrams of this in the tips section that will probably show you what you need to know under "Christie projectors".

Posted by Mark Gulbrandsen (Member # 72) on 01-10-2002, 11:42 AM:

Yea, don't loose the ball jewels, those are mined in the basement of the Christie Plant and ground to exacting specifications in the attic of the Christie plant. They cost 500.00 a carat to replace! Also they are not supposed to be oiled. Thats the reason for the ruby in the first place. Almost any oil will dry up(evaporate) quickly from the heat. Even LaVezzi super oil won't withstand the relentless heat in the trap for very long.
Mark @ GTS