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Author
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Topic: Century SA-W Speed Problem
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Frank Angel
Film God
![](http://www.film-tech.com/ubbmembers/248b.jpg)
Posts: 5305
From: Brooklyn NY USA
Registered: Dec 1999
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posted 06-19-2009 04:49 AM
Close, Gordon -- after playing around with this thing for hours today, listening intently to the motor with my ear up against it, running it with film, without film....film threaded thru the intermittent, not thru it, film reel on the takeup, nothing on the takeup, and then the revelation: let's see what happens with the yellow rollthane belt tension removed -- I slipped it off the takeup arm pulley. I didn't take the belt completely off, I just slipped it off the pulley and let it ride on the shaft, and it was actually still turning the takeup reel, With that, the motor goes from oscillating to perfectly running smoothly. Rollathan back on the pulley and the motor does its rhythmical speed oscillation, which, btw, is so bad that the sound drum won't even smooth it out....you can see the film in the sound head dancing with the rhythm of the motor sound.
Conclusion: the belt tightness (not the resistance of the takeup reel) was what was somehow loading the soundhead drive train and producing the drag on the motor.
As strange at is seemed to me, it WAS the yellow rollothan belt that's causing the motor to load, although I must say, feeling the taughtness of the belt, it seemed loose enough to the touch. Mind you, it's no tighter than it's ever been -- I mean, this same belt has been on this same machine for years. But there it is, cause and effect: with the projector running film with the rollthane belt engaged, the motor severely oscillates. With the belt taken off the takeup arm pulley, the motor immediately runs smoothly again. Stretching the belt in a kind of mad fit after wasting my time for hours -- I just pulled on the plastic belt with all my might trying to stretch it -- fixes the problem -- the motor's running normally and smooth as a baby's butt.
So WTF? This stuff SHRINKS? Changes with the humidity? -- we are outdoors and it has been raining nonstop since 1910 here in Brooklyn, but that seems unlikely, but there it is, cause and effect. Besides, I never argue with success.
Now I should have as much luck with getting rid of the IREM HUMMMMMMM.
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