Repairing a B&H Model 383A 8mm projector

[Leo Langston]

My old B&H Lumina 1.2 projector isn’t working correctly. The motor runs fine as do the the reel spindles in Fwd and Rev. what is not working is the lower toothed sprocket of the autothreading mechanism (see RED circle). I have removed the back cover and all gears on the back side seem to be rotating correctly but the lower sprocket is frozen. Can the clear plastic film trough that surrounds that sprocket be removed. If yes, then how do you remove it? Is it connected to the upper film trough such that both have to be removed together? I see one large head screw on both the upper and the lower feed troughs. I removed the one on the lower section bit it doesn’t come off and I don't want to force and break it.

[Nantawat Kittiwarakul]

I guess that you may have to remove the other screw on the right as well, and remove it as the whole assembly.

Caution - there might be coil spring/lock pin/other booby trap hidden behind.😨 All hell might break loose then.

On the second thought, please make sure that the drive gear is still secured to the shaft. It is possible that the grub screw may work loose and let the gear spin around the shaft instead of spin the shaft with it.

[Leo Langston]

I know the sprocket with the black knob is very hard to turn. The upper sprocket rotates freely when the projectornis projector is running. So it seems like that lower sprocket is frozen in place. I can see the dual gears on the back side turning when the projector is running.

[Shane C. Collins]

Could there be a large piece of film or leader stuck somewhere inside the sprocket assembly? Although I wouldn't think film would have the strength to stop this gear from rotating. Maybe a pin or something is loose and no forward motion.

[Leo Langston]

Anything is possible. That why I wanted to see if it was easy to remove the clear plastic parts that surround that sprocket so I could see if anything was jamming it. The plastic trough makes it impossible to see what’s happening to that sprocket. I posted a short video of the projector on youtube https://youtu.be/P1WV__tS7Lg

Any ideas for repair are welcome.

[Leo Langston]

I can now see that the lower sprocket ‘axle?’ Is not moving like the upper sprocket does. That what is making the loud rapid clicking sound in the video. Those axles have a slot and you can use anscrew driver to rotate them by hand and I can do that but the lower is much stiffer to move than the upper one. I see nothing in the film path that one bind it up. So my next questions are can someone tell me how to remove the clear plastic film paths from the sprockets. I have removed all the obvious screws and will not slide off. Is there some trick or hidden screws that need to be removed? Also is there an easy way to remove the large gears from those sprocket axles on the back side of the projector. See photo. I might be able to lube those axles if I can get better access to them. Is there a service manual on line that details the disassembly of these projectors?

[Leo Langston]

Does the little spring clip (RED circle)that appears to be holding this small metal plate need to come off before the entire film path can be removed from the projector body?

[Shane C. Collins]

Those gears in the back appear to have springs attached that probably keep them in place. Not sure what kind of tool you would need to remove those springs. You would need to be careful as not to damage those springs. There also appears to be washers just in front of those square plates. If you can remove this hardware those gears would release. Then the sprocket drive should slip out I'd imagine. What you really need is a service manual so you can see the exploded view of how these sprockets and gears are held together.

[Maurice Leakey]

Leo
I agree with Shane.
There seems to be no connection between the lower worm gear and its sprocket shaft. Compare it with the gear/shaft above and see where the difference lies.
Regarding the spring clip. The spring gives tension to the side of the gate and applies gentle pressure on the film as it goes through. There doesn't seem any need to touch it.


Maurice

[Leo Langston]

When running in gear both of the 2 rear gears on the lower sprocket turn freely on that worm gear. But the sprocket does not so that long flat metal spring/clutch (red arrows) stays in the same place and just makes that clicking sound as it rides over the yellow gear. On the upper sprocket gear that flat metal spring/clutch spins with the gear. I assume that is a safety feature that allows the gears to keep rotating if the sprockets get hung up by a film break. I can rotate the lower sprocket with a flat blade screwdriver but its a lot stiffer than the upper one so something is binding on the shaft.

[Leo Langston]

Well I guess I got lucky. Applying the penetrating oil to that lower sprocket mist have freed it up because the projector works fine now. The lower sprocket turns easily and rotates in sync with the upper one. I have watched a couple of small reels and everything seems to be working as well as expected. Thanks for all the comments and recommendations. Now to start resplicing broken film and leaders. I have new presstapes and a Quick Splicer that was clipped inside the projector cover. I just have to relearn how to use them.