8mm Forum: Question about eh Chinon 7500

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Posted by Andy Dorfman (Member # 6146) on October 31, 2017, 01:29 PM:

I have an old Chinon 7500 and the take up reel isn't turning. The spring belt seems to be in good condition, but I can't even understand what drives that pulley system.
It appears to not be connected to any of the drive mechanisms. The front-most shaft has gears, but they're a half an inch away from the nearest neighboring gear shaft. Is it supposed to somehow move into place when the projector is in forward mode?
Any help would be appreciated. I usually have a decent eye for figuring this stuff out, but I'm mystified.
Thanks in advance.
Andy

Posted by Paul Browning (Member # 2715) on October 31, 2017, 02:10 PM:

If its like the 1200 , then inertia throws the gear train in the correct direction to engage the take up. There is a clutch mechanism in there too, which does play up on the chinon 1200 machine, I suspect its the same mechanism on yours, get some pictures up here, lets have a look ......

Posted by Janice Glesser (Member # 2758) on October 31, 2017, 06:26 PM:

I have a Chinon 7800 Andy...Don't know how close it is to the 7500. I'll try and take a look at it sometime tomorrow after all my Halloween gear is cleaned up.

Posted by Andy Dorfman (Member # 6146) on November 01, 2017, 03:44 AM:

Thanks for your replies.
If the clutch mechanism is supposed to move the relative locations of the gears, it seems to me that, for some reason, it isn't functioning.
I'm uploading a picture of the inside of the projector. The spindle on the lower left is the one that would drive the take up reel, but it appears to be at a fixed location, so I imagine it's the one above it that's supposed to move down to drive it.
That one seems fixed as well though - I can't seem to budge it with my finger, although it spins fine and turns the feed reel (which just spills film onto the floor in forward mode).
If it's a clutch that's not working, how fixable is that?

Posted by frank arnstein (Member # 330) on November 01, 2017, 04:48 AM:

Yes Andy,
it's the one above it that's supposed to move down to drive it.

It's obviously stuck so you will have to free it up. Spray behind the gear or remove it to see why it won't slide down. Old grease gone hard is the usual reason for this. It's mounted on a swinging bracket that's attatched to the driving gear next to it.

See how you go.

dogtor frankarnstein [Smile]

Posted by Joe Taffis (Member # 4) on November 01, 2017, 04:56 AM:

Top photo in forward position, bottom photo reverse position [Smile]

Posted by Andy Dorfman (Member # 6146) on November 01, 2017, 12:05 PM:

Ah... thanks all. I'm stuck in reverse!
Frank - what would you recommend spraying back there as a first resort? DeoxIT, or something else?
I've tried to remove the nut holding that gear, but it only comes lose up to the point where the edge of the nut is flush with the edge of the spindle. Then everything turns together and it doesn't come off any further.
Because there's a spring behind it, there's nothing really to grab onto to hold the spindle in place.
Any suggestions?
Because my primary task is to transfer about 2000 feet of film, I may just operate the projector with the back off and manually move the clutch as needed (now that I know exactly which gear had to move and where, I was less timid about giving it more effort).

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