8mm Forum: Elmo st-1200 jitter

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Topic: Elmo st-1200 jitter

Norman Fisher
Junior
Posts: 18
From: Irvine, CA USA
Registered: Oct 2005

posted July 19, 2009 09:48 PM

Hi gang, My ST-1200HD picture has started to "jitter" up and down during projection, and it's getting a bit annoying. I replaced the belts and it didn't seem to help. Cleaned the guides, and still nothing. Never have had this problem before. I have an ST-800 too, and the films play perfect on it. Any ideas what might be the culprit and how to fix it? Much appreciated! Thx!

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Dino Everette
Phenomenal Film Handler

Posts: 1535
From: Long Beach, CA USA
Registered: Dec 2008

posted July 20, 2009 02:20 AM

Have you checked gate tension or your loop size since those usually are the first things I think of regarding jitter? I actually had a similar problem with an ST-1200 HD that I recently acquired and it was caused by the latch for the lens/gate assembly when it swings and snaps into place. It was just loose enough that it wasn't keeping the film smooth and tight as it passed through. I bent it back a tiny bit so it would provide a tighter grab and that was all it took on mine, hope yours is an easy fix like that.

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"You're too Far Out Miss Lawrence"

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Norman Fisher
Junior
Posts: 18
From: Irvine, CA USA
Registered: Oct 2005

posted July 21, 2009 09:07 AM

Thanks Dino! No I have not checked the gate tension. I will do so when I get home from work tonight. [Smile]

Hope that's the answer!

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Kevin Faulkner
Film God

Posts: 4071
From: Essex UK
Registered: Jun 2003

posted July 21, 2009 05:18 PM

There is one or two other possibilities which spring to mind but try the easy one from Dino first.

One is that the cam itself needs greasing and the other is that the plastic round piece that runs in the cam has got worn. But thats another story and not until you have checked the obvious.

Did this suddenly start to happen and does putting any lube on the film itself help? The Elmo's dont like dry or green film. Try running the film through a cloth with some film lube while the film is running to see if it stops the problem. I know you say the same films run on the ST800 ok but these machines all have their own inbuilt personalities.

Kev.

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GS1200 Xenon with Elmo 1.0...great combo along with a 16-CL Xenon for that super bright white light.

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Tony Stucchio
Jedi Master Film Handler

Posts: 625
From: New Jersey
Registered: Dec 2005

posted July 21, 2009 07:12 PM

I would also decrease the tension on the take-up reel. This is sometimes a problem -- if it is too strong the lower loop is lost very easily.

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Roy Neil
Expert Film Handler

Posts: 203
From: Menlo Park, CA
Registered: Sep 2007

posted July 22, 2009 04:47 PM

Tony - I had a similar problem with losing the lower loop on autothread with an ST-1200HD I was repairing.

Decreasing the takeup tension will prevent the film from being 'yanked' and cure the symptom but introduces a new problem with takeup on 1200' reels due to insufficient tension.

The 'real' problem is the small torsion spring that pushes the green plastic guide against the lower sprocket - if this spring is out of its 'slot' or not providing sufficient tension, the film can be 'yanked' through the sprocket causing the lower loop to be lost. Tensioning the spring tighter will eliminate the problem and allow for a firm takeup tension.

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Jon Addams
Jedi Master Film Handler

Posts: 638
From: New York, NY, USA
Registered: Apr 2007

posted July 22, 2009 11:41 PM

Hi,

Just how one does decreases the take-up’s tension?

Thanks

Jon

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Tony Stucchio
Jedi Master Film Handler

Posts: 625
From: New Jersey
Registered: Dec 2005

posted July 23, 2009 07:06 PM

Take the back cover off. While holding the takeup spindle, on the outside of the machine, rotate the knob (connected to the gear that turns the spindle) on the inside of the machine counter-clockwise.
It takes some trial and error to get it to where there is not too much tension, but not too little that you wind up with a floor full of film for a 1200 footer.

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