8mm Forum: Frame gate and sprockets are moving in opposite directions!

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Topic: Frame gate and sprockets are moving in opposite directions!

David Rebman
Junior
Posts: 1
From: Orlando, FL, USA
Registered: Nov 2015

posted November 22, 2015 08:00 PM

My kids got me a DeJur 750 8mm projectors. l'm looking forward to a new hobby. It appears to be in good working order except one thing. When I thread the film in from the top reel both sprockets, top and lower, rotate clockwise while the frame gate is moving the film up. The film through the frame gate and sprockets are moving in opposite directions! I would appreciate help from someone that has this projector or is familiar with my problem.

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Jim Schrader
Phenomenal Film Handler

Posts: 1628
From: Savage, MN, USA
Registered: Jun 2003

posted November 22, 2015 10:29 PM

Generally on these type of units the top and bottom spindles would spin clockwise the top sprocket should spin counterclockwise and the bottom should spin clockwise. Is the unit in rewind? Or normal projection mode? Is it the kind with 3 switches? And with variable speed?

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jim schrader
"Let's see “do I have that title already?"

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Winbert Hutahaean
Film God

Posts: 5468
From: Nouméa, New Caledonia
Registered: Jun 2003

posted November 22, 2015 10:49 PM

There is a possibility that the belt was installed in a wrong way. Belt should be seen like a 0 shape between the gears (front and rear). If it is an 8 shape than the two rollers will turn in the opposite direction one to the other.

Good luck!

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Winbert

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William Olson
Master Film Handler

Posts: 287
From: Poughkeepsie, NY USA
Registered: Jun 2010

posted December 16, 2015 05:52 PM

I know this machine. When projecting forward, both sprockets should be rotating clockwise. The supply spindle shouldn't rotate by itself except in reverse mode. The take up spindle should rotate clockwise. Make sure both sprockets engage the sprocket holes of the film and that the sprocket gates are closed. Be sure you have a good loop at the top and bottom of the film gate - at least an inch or so for both. If the film is moving up the film gate during forward projection (and causing the top loop size to increase while decreasing the bottom loop size), this could be a claw problem. The claw causes the intermittent pull down of one frame of film at a time in the film gate. Poor film condition might also cause this.
As for belts, I know the supply and take-up spindles use chains (instead of traditional belts) which are concealed within the arms. As for the main drive belt, it doesn't sound like this is the problem. Believe me, you wouldn't want to mess with that anyway.
There are YouTube videos that show this model in action. I notice that some of these videos show the film being fed to the top sprocket counterclockwise and some clockwise. I always feed film into a projector clockwise. If you don't know what I mean, watching these videos will illustrate what I mean.
Good luck.

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