Film-Tech Forum ARCHIVE: Christie 35GPS aperture and turret motor timing

This is topic Christie 35GPS aperture and turret motor timing in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Michael Schaffer (Member # 1204) on 01-21-2006, 03:21 AM:

According to the manual, the motor on-times are set with trimpots on the PCB on the non-operating side. I have a relatively new location in Mexico (1 1/2) years which complained about the aperture not going up and down far enough.
This looks like something which should be quick and easy to adjust. But - since the location is several hours away and I will only have time to go there for one day, I want to take all potentially needed spare parts with me.
So, in your experience, is this a problem that is usually cured by adjusting the trimpots or are there potential other problems? When the motors are overtimed the first time, does this lead to deterioration of the drive wheels because they overrun for too long and wear down too much? Could the motors be timed correctly but the drive wheels are slipping because of mechanincal misalignment?
I don't think I will find problems like excessive dirt build-up in the aperture area which would jam the plate since the operators in that location usually clean really well. But I will still check that, of course.
BTW, how are the motors timed on older versions of the Christie projector?

Posted by Frank Dubrois (Member # 3042) on 01-21-2006, 09:37 AM:

I found that it was nothing more than a small turn of a trimpot. I adjusted ours about 6 months ago and haven't noticed any negative effects. Ours "overrun" about one second, in my experience, not much more is needed, and if it is, perhaps the aperature plate is sticking?!?

Posted by Mark Gulbrandsen (Member # 72) on 01-21-2006, 12:10 PM:

Be sure to adjust the timming with the gate hot after a normal feature film is run. Allowing the projector to get to operating temperature matters alot with this adjustment. When its hot the parts expand and the aperature generally slows down even more.... I believe this is a 555 timer circuit who's timming is also greatly effected by heat.

Happy timming adjustment!

Mark