8mm Forum: ST-1200 Belt Adjustment

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Topic: ST-1200 Belt Adjustment

Steve Klare
Film Guy

Posts: 7016
From: Long Island, NY, USA
Registered: Jun 2003

posted January 12, 2010 07:20 PM

I'm adjusting to life with my new Elmo ST-1200. It's my first and only my second Elmo. The last couple of reels I noticed the tones were a little bassy. The men sound more baritone than I expect and even the women seem a little masculine.

So it's a new projector, time to pop off the cover and see what's going on inside.

I figured it wasn't a matter of adjustment since this machine has a synchronous motor and the speed should reflect line frequency. It had to be some kind of slippage.

The motor belt is on the smaller motor pulley, which makes sense for 60 Hz. (more motor revolutions for a given belt speed.)

I did notice a tensioner pulley for the motor belt that wasn't actually resting against the belt (Ah Hah!).

This doesn't seem to have a spring for preset tension, but looks like it's supposed to be manually adjusted and then fixed in place with a set screw. The machine was delivered with a new set of belts. It looks like the last owner just forgot to readjust.

The question is what is the proper way to adjust this idler pulley? Obviously too tight or too loose are both making for trouble, but what's tight enough?

Thanks!

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All I ask is a wide screen and a projector to light her by...

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Josef Grassmann
Expert Film Handler

Posts: 190
From: Hennef-Sieg, Germany
Registered: Apr 2005

posted January 13, 2010 08:51 AM

It is´nt a critical adjustment (if the belt hardness is not too high).
There is about 3 to 4 mm mm shift, only.
If there is no slip in middle postion, leave it there.
So you have the choice for a further adjustment in future.

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