8mm Forum: Elmo ST-1200 issues Help!

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Posted by Norman R. Fisher (Member # 5557) on 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!

Posted by Steve Klare (Member # 12) on 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.

Posted by Andrew Woodcock (Member # 3260) on September 07, 2016, 08:23 AM:

Me neither Steve. As you say, typically on these the issue is with the speed running slower than designated not faster, or varying excessively.
It's also hard to imagine without some oversized drive wheel being fitted, how one of these could ever possibly run fast??
I think your explanation regarding comparisons made to another machine ring true here.
Certainly no change of drive belt would ever make one of these run faster than designated speed thats for sure.

Posted by Steve Klare (Member # 12) on September 07, 2016, 08:29 AM:

I've noticed with mine, the pitch seems higher in the opening minute of a film and then settles down.

Is the machine slowing down as it warms up or is my nervous system adjusting to the pitch and calling it "normal"?

-I've made my bets!

For all I know, my ST-800 is really running slow and the ST-1200 is dead nuts!

I want to build an optical frame rate detector. I have the schematic drawn. I have the parts list worked out.

Where does the time to build it come from?

Posted by Andrew Woodcock (Member # 3260) on September 07, 2016, 08:32 AM:

Expect to see considerable variation Steve, once built.
I would be interested in that schematic though Steve in order to accurately match my Bauer visually to start off with, with my variable speed digital source for recording purposes.

It would certainly give me a head start to know the precise frame rate to match to on any given day.

As things stand, it's something I have to trial on each occasion before beginning the work, just to get the two in sync to begin with.

Even an optical tachometer would do me in fact with a piece of reflective tape on one of the shutter blades.
I'd just need to keep removing the lamp house cover though to obtain an initial reading I suppose.

Much better I guess if I could fit a precise digital frequency meter from a built in permanent optical sensor.

Time to peruse the old RS website me thinks. [Wink]

Posted by Steve Meyer (Member # 5197) on September 07, 2016, 09:06 AM:

Hi Norman R. Fisher,

Leon Norris is definitely the man to reach out to on fixing Elmo projectors. He has many parts for them too. He lives in PA.
His number is 610-272-3205.

It sounds like the claw assembly to me. But of course I don't know. I had a jittery picture, not a sold picture at all on one of my Elmo's. Leon put in a new claw assemble and the picture now is rock solid no jitters in any direction.

Good Luck

Posted by Jim Schrader (Member # 9) on September 07, 2016, 09:47 PM:

It may take several tries to get ahold of Leon his fax kicks in often just keep trying. He's a real friendly guy.

Posted by Norman R. Fisher (Member # 5557) on September 11, 2016, 05:49 PM:

Thank you Andrew, Steve and Jim. You made me realize how much I love my Elmo ST 800 over the 1200! Ha! Seriously though, I do need someone to look at it. The jumping up and down of the image is getting so bad now, I can't even watch anything anymore. I will try to get in touch in Leon about it.

On mine Steve the "sped up" pitch doesn't get better when warming up, it stays consistent. Hopefully both can be resolved by Leon. Cosmetically I like the 1200 over the 800 when screening for friends.

Posted by Steve Klare (Member # 12) on September 11, 2016, 08:44 PM:

The ST-800 is a respectable machine. It puts up a decent image and has nice sound. The joy of it is the simplicity, and the reliability that comes with it.

Still the same, my ST-1200HD is on the injured list until my new lower guide gets here. Wouldn't you know it? -now every time I decide I want to watch a film it turns out to be on 1200 Foot reels or has stereo sound!

Posted by Tom Photiou (Member # 130) on September 12, 2016, 06:58 AM:

I've never heard of a 1200 running too fast either, unless one of the pulleys or drive clutches has been replaced with one the wrong size.
As for picture image jump, this could be many things including a orn claw cam or film guide or a worn film aperture.
The claw cam is a part that does wear on these and as it gets hotter jumps even more. [Wink]

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