8mm Forum: Elmo ST-1200 focus knob question

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Topic: Elmo ST-1200 focus knob question

Barry Fritz
Phenomenal Film Handler

Posts: 1061
From: Burnsville, MN, USA
Registered: Dec 2009

posted January 14, 2011 11:16 PM

I just got this projector for 5 bucks. Needs lamp and motor belt, otherwise appears in good shape. Came with case and User Manual. However, when I opened the front cover, I discovered that the focus knob would come right off, and did not move the lens when it was on. The knob was stuck on via some grease. Below are some pics of the knob and what it sits on. The white part is screwed into the lens holder barrel. What is missing here? It doesn't appear that anything broke. There are threads on the inside of the square white piece that is in the knob, but no threads seem to be in the corresponding white piece on the right. Are these parts still available if I need to replace them? Thanks in advance.

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Roy Neil
Expert Film Handler

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

posted January 15, 2011 01:10 AM

The flipside of the small white plastic piece should have a spiral groove - this is what the pin on the lens rides in so when you rotate knob the lens moves in/out.

There is a small piece of aluminum trim on the outside of the black knob that obscures the screw/hole, and unless you remove both the trim and then the screw, you cannot remove the knob.

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Jean-Christophe Deblock
Jedi Master Film Handler

Posts: 693
From: Grimbergen, Brabant, Belgium.
Registered: Mar 2007

posted January 15, 2011 07:52 AM

Hi,

I've got these problem once.

I've repair this with super Glue 3.

That's all.

Best regards,

JC.

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Barry Fritz
Phenomenal Film Handler

Posts: 1061
From: Burnsville, MN, USA
Registered: Dec 2009

posted January 15, 2011 09:24 AM

Thanks for replies. Roy, You are correct, the backside of the white piece does have that grove. So, is this a broken piece, or is the black knob suppose to be attached to the white piece with a screw that is missing? It seems that would be the case. The knob has to be able to be separated from the white piece otherwise you would not be able to get to the three screws that hold the unit onto the lens barrel.

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Roy Neil
Expert Film Handler

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

posted January 15, 2011 09:44 AM

Yes - you are missing the small screw and the thin round piece of metal that is glued onto the knob to hide the screw. I hope you have the three screws that hold the assembly in place, otherwise you need those too. Make sure you properly mate the white piece with the knob ( see square inset on knob and square protrusion on white plastic )

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Barry Fritz
Phenomenal Film Handler

Posts: 1061
From: Burnsville, MN, USA
Registered: Dec 2009

posted January 15, 2011 10:32 AM

Thanks Roy: I do have the three screws you mentioned. I took the part off of the barrel myself. I'm a little confused about how the thin piece of metal and screw you mention work. Are you talking about The metal piece on the front shown here?

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Chip Gelmini
Phenomenal Film Handler

Posts: 1733
From: Brooksville, FL
Registered: Jun 2003

posted January 15, 2011 11:46 AM

I had this happen to me once and it was a royal pain in the butt.

However, I happened to have a spare unit for parts. I swapped the entire front gate assembly which included the focus knob assembly. So it was fixed in less than 10 minutes. But still a pain.

I wonder if this happens because a user trys to remove the lens and thinks they must pull on the knob to slip the lens in/out. In some models such as Bell & Howell that would be the correct method.

On the Elmo ST series, you rotate the knob to the 3:00 position clockwise until it stops. Then pull the lens in/out.

Never ever pull on the knob. Always rotate it.

The only other reason I suppose would be factory glue goes bad over time and it just comes loose.

-cg-

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Claus Harding
Phenomenal Film Handler

Posts: 1149
From: Washington DC
Registered: Oct 2006

posted January 15, 2011 12:22 PM

Barry,

If you find the knob business is too troublesome, I do have a complete lens mount/focus assembly available.

Claus.

--------------------
"Why are there shots of deserts in a scene that's supposed to take place in Belgium during the winter?" (Review of 'Battle of the Bulge'.)

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Barry Fritz
Phenomenal Film Handler

Posts: 1061
From: Burnsville, MN, USA
Registered: Dec 2009

posted January 15, 2011 12:24 PM

Well, I removed the silver plate on the top of the knob and found that the screw was there and holding the little bit of square white nylon. If that screw was longer and went down into the nylon part with the channel, that part would not break off. I fashioned a tiny stud to go into the nylon parts and put appoxy on it and the small area where it broke off. Will see if it holds. I think you may be correct that users pull on it, and that is what causes the break. Not the best design. Thanks for the input.

Edit addition: Thanks for the offer Claus. Belts and lamp are on order. Once I get it running, and am able to test it out for other problems, I may take you up on your offer if it is working ok but the apoxy doesn't hold. PM me at barryfritz at hotmail dot com with a price. I tried to PM you but couldn't.

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