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Author
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Topic: Elmo ST-1200 issues Help!
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Norman R. Fisher
Junior
Posts: 5
From: Dallas, TX, USA
Registered: Sep 2016
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posted September 07, 2016 12:51 AM
Hello all, I know from the past reading of posts here, there are a lot of knowledgeable film buffs on this board. My Elmo ST-1200, which I have had since 1976, has started to develop issues. It's only been serviced once since that time amazingly enough, and that was about 6 years ago.
When playing films, there is a noticeable and very slight bouncing up and down on the image. An up and down "jittering" as it were. I know it's not the films, as I have an ST-800 and they play perfectly on it. That's issue #1. Issue #2 is the projector seems to be running fast. There is a sped up sound to the voices, again not noticeable on my 800 model. I have read about folks Elmo's running slow, but never fast. I know the belts seem to be correct for US voltage. But wondering if anyone else had this fast playing issue? I thought maybe the belts might need replacing? I have had them in there for a few years, and bought them from a dealer on Ebay. Who is making belts for the Elmo now? I suppose I could try a new set of them to see if that stops the issues. Any dealer recommendations? Thanks everyone!
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Steve Klare
Film Guy
Posts: 7016
From: Long Island, NY, USA
Registered: Jun 2003
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posted September 07, 2016 08:14 AM
Hi Norman,
Welcome to the 8mm Forum!
The ST-1200 is a machine built around mathematics done a long, long time ago. All decently designed machines start with calculation, but this is doubly true here. For example, your ST-800 (and mine) have DC motors where the speed follows the applied voltage. There are adjustment pots inside to change the motor voltages, so you can set the frame rate dead on.
The ST-1200 is different. It's got an AC motor, which follows the line frequency instead of the voltage. This means that the frame rate is the result of some long multiplication of ratios of pulley diameters and gear ratios and the line frequency with fudge factors for stuff like friction and temperature variations. It (for example) means if the boys down at the power plant shovel in too much coal one night, your frame rate will be too high. It also means there's not a huge amount you can do about it when the variables are a little TOO variable.
On my ST-1200 the motor pulley wore down, and my frame rate was noticeably low. (Actresses started to sound a touch too masculine...They can't all be Beatrice Arthur!). I replaced it with a new pulley and all of a sudden the pitch seemed just a touch too high!
It's possible the problem isn't so much your ST-1200, but the fact that you also run an ST-800 (my main pair too.) When you run a film on one and then switch to the other, your ear notices the difference and your brain fixates on it. (-been there). You could tweak the speed on the ST-800 to match, but if everybody sounds like Alvin and the Chipmunks you've only masked the problem.
My favorite belt seller is isellprojectorbelts on E-bay, but I can't imagine how a belt could make a machine run too fast.
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All I ask is a wide screen and a projector to light her by...
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