This is topic Elmo ST800 in forum 8mm Forum at 8mm Forum.
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Posted by David Hyde (Member # 4752) on April 05, 2015, 08:35 PM:
I was wondering if the pinch roller should be pressing against the film and flywheel roller at any stage. Mine does not and I'm wondering if not, how does the flywheel turn and stabilize the sound.
Posted by Steve Klare (Member # 12) on April 05, 2015, 09:20 PM:
When you turn the select knob clockwise until the lamp lights, you are now in normal projection mode. At this point the sound chute should clamp down on the film, the pinch roller should pinch, and you should have sound. This is the second forward position on the switch. The first has the chute lifted up to allow for threading film. Both reverse positions have it up too.
If you turn the knob back and forth, you should see the chute pivot up and down over the heads. (You don't even need to plug it in to do this: it's all mechanical.) It needs to clamp down fully to get the sound to work well.
Posted by David Hyde (Member # 4752) on April 05, 2015, 09:58 PM:
I thought as much. The pinch roller will not make contact with the film/flywheel roller in any condition so I will need to take a deep look. I can see that I need to remove the flywheel which I have done but looks like I need to remove the motor to get at the mechanics underneath, right?
Posted by Steve Klare (Member # 12) on April 05, 2015, 10:44 PM:
I think you can leave the motor where it is. The flywheel is easy to remove if you need to, the motor: not so much!
The flywheel is driven by the film itself on this model. When the pinch roller pinches down the film spins it and the flywheel through its shaft.
What you have is this kind of complex chain of levers and rods that starts way back at the selector knob. A cam on the knob pushes out for all positions except "forward, lamp". When you twist the knob into this position, the follower on the cam sinks in and the linkages allow the chute to sink down under sprint tension.
In your case, something is probably stuck and needs to be freed up.
One time on my machine some debris lodged between the cam and the follower and prevented it from falling fully into position. I lost sound until I got in there and cleaned it out.
Posted by frank arnstein (Member # 330) on April 05, 2015, 10:47 PM:
There is a long extension spring that pulls the pinch roller against the flywheel roller. Check if yours still has that spring in place.
If it has, then increase the tension on the spring using the adjustment provided at one end. Lube the pivot shaft if it's dry.
There should not be any need to remove the flywheel to fix this so concentrate on the obvious stuff at the front first.
Posted by Paul Browning (Member # 2715) on April 06, 2015, 06:04 AM:
Janice had this very same problem with her st800, I think she and another forum member found a make do and mend solution, never did like the main function switch idea on these projectors, so much to do for such a simple rotating switch, but if it goes wrong its starts a chain of events, and its buried in the depth of the machine, its very much like the heater matrix in your car, the whole thing is built around it, but like Steve says there is levers and cams in a chain before this bit so they have to be doing there job first. I do remember taking some photos for Janice to get some idea of where this should be when working correctly, and there not much in it, taking the back off with the mains lead unplugged shows you the actions, its a very good projector when working correctly.
Posted by Janice Glesser (Member # 2758) on April 06, 2015, 09:56 AM:
David take a look to this thread. It's lengthy, but has info and pics of the area you will need to gain access to troubleshoot your chute problem.
You do not have to remove the motor... just the flywheel and then the metal guard panel and gears behind the panel. There are photos and instructions in the above link.
Posted by David Hyde (Member # 4752) on April 06, 2015, 05:21 PM:
Thanks for all your help here. I have removed some debris around the lever mechanism and everything is working fine now. I'll get back to the forum as soon as something else goes wrong.
Posted by Andrew Woodcock (Member # 3260) on April 06, 2015, 05:48 PM:
And of course, thank Steve and Janice, Paul and Frank personally for their invaluable advice!
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