Film-Tech Forum ARCHIVE: Chinon 2500GL projector, loosing loops

This is topic Chinon 2500GL projector, loosing loops in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Michael Gerrity (Member # 7734) on 07-01-2013, 01:12 AM:

I have a Chinon 2500GL Dual 8 Projector, however, I am having some issues with the film slipping through the gate. As far as I can tell what's happening is the film is loosing it's lower loop. Does anyone know of a good solution to fix this? If I can I'd really like to hold onto this projector since it does dual 8.

Thanks!

Posted by Leo Enticknap (Member # 534) on 07-01-2013, 04:51 AM:

There are a number of possible causes.

I'd guess that the most likely one is an issue with the mechanism that drives the claw in the side of the gate, which inserts through a perforation in the film and pulls it down. If that's not doing its job properly, but the sprocket below it is still rotating, the sprocket will in effect be dragging the film through the gate, thereby causing the loss of a loop.

Try opening the back cover of the projector (with the power disconnected, obviously), lacing up some film in it and then advancing the mechanism manually, by rotating the inching handle (if there is one) or drive shaft. Does it occasionally miss a frame as it moves intermittently through the gate? If so, that's your culprit, and you possibly need to adjust the claw mechanism so that it extends further on each cycle.

If not, worn belts is another thing to check for, especially if any of them are toothed.

Another possibility could be a broken tooth on the lower sprocket, in which case you're probably looking at trying to get another projector on Ebay to use for spares.

Posted by Bruce McGee (Member # 131) on 07-01-2013, 02:10 PM:

Excessive take-up tension can cause lower loop loss.