8mm Forum: Chinon SS1200 Rewind Problem-I'm stumped

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Topic: Chinon SS1200 Rewind Problem-I'm stumped

Alan Rik
Film God

Posts: 2211
From: New York City, NY, USA
Registered: Jun 2003

posted August 15, 2017 05:56 PM

Unfortunately I threw the towel in on this one. It was NOT designed to be worked on as the electronics were buried..buried..buried in the machine. I had to take apart the entire thing and still there were more to remove. When it became apparent that I would have to get it down to the bare bones to work on it I decided against it. Life is too short! [Smile]

Good luck! It really is a nice machine and if you can get that sorted that would be great.

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Andrew Woodcock
Film God

Posts: 7477
From: Manchester Uk
Registered: Aug 2012

posted August 15, 2017 06:16 PM

Can't say I blame you Alan in any way regarding this one. [Wink]

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"C'mon Baggy..Get with the beat"

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frank arnstein
Jedi Master Film Handler

Posts: 534
From: Gold Coast. Australia
Registered: Jan 2005

posted August 21, 2017 07:43 AM

Greetings to the forum members who followed this interesting thread,

It seems this problem effects nearly every Chinon 1200 in the world.

After some careful study I have arrived at the root cause of this conundrum and will happily share the fix with anyone that asks me.

Dogtor Frankarnstein.

[ September 10, 2017, 06:31 AM: Message edited by: frank arnstein ]

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Andrew Woodcock
Film God

Posts: 7477
From: Manchester Uk
Registered: Aug 2012

posted August 21, 2017 08:25 AM

Yet another great addition to add to the "Index of Technical Topics" here.

Well done Frank for sharing and well done too for discovering the root cause in the first instance! [Smile]

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"C'mon Baggy..Get with the beat"

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Paul Browning
Phenomenal Film Handler

Posts: 1006
From: West Midlands United Kingdom
Registered: Aug 2011

posted August 21, 2017 12:42 PM

Thanks Frank, i'll check this out. I have a new machine and this is also present on this, but not as bad as some, like Alan Riks machine, but perhaps in my case it could be solidified grease in there. I do know the gear trains are greased up, but I will renew this now, to reduce friction between the gears. Thanks again for some great information.

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Mark L Barton
Jedi Master Film Handler

Posts: 621
From: Bristol, South Glos, England
Registered: Mar 2009

posted June 24, 2018 06:19 AM

I have a Chinon S1200 Stereo with exactly the same issue, in rewind, and down to the last 300 odd foot the rewind goes from powerful to sluggish to stop, I love this projector and in all other respects its superb ( I have several ST1200s and GS1200's, but always reach for the Chinon for a quick play of a new title) So, did any one find a cure, was it too much hardened grease, or electronic issues (if its that I wont even go there)

Thank you

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frank arnstein
Jedi Master Film Handler

Posts: 534
From: Gold Coast. Australia
Registered: Jan 2005

posted June 27, 2018 07:27 AM

Hi Mark,

The actual cause is the sticking pawl of a rewind Sprag clutch. This clutch is inside the big plastic gear which the toothed belt drives. It's behind the big plastic washer on the take-up drive shaft.
This small mechanical clutch ratchet/pawl is now stuck in one position due to hardened old grease. It won’t allow the free-wheeling in one direction needed for fast easy rewinding. Instead it drives the toothed belt and gear unnecessarily. This causes a lot of unwanted load and extra noise which forces the rewind to slow and then end prematurely.

To free up this "Sprag Clutch" I would spray Isopropyl alcohol or some other evaporative spray onto the sticking clutch parts to dissolve and wash away the old grease and dirt.

You may need to partially dismantle behind the washer to get to the little ratchet parts. Watch out you don't loose any tiny springs or other bits there.

When working properly, it must allow slip of the shaft when rewinding film and lock up when projecting film. Observe the clutch working then reassemble and test again by hand, rotating the take-up spindle in both directions by hand, to test the lock and release of the ratchet pawl.

If you are successful, the normal fast rewind ability of your machine will return and it will be quieter in rewind as well. Lubing the gear train axles in both arms will reduce friction even further. Dry plastic is noisy and drags.

So see how you go and let us know.

Dogtor Frankarnstein

[Wink]

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At Projector Heaven the Focus is always on Detail.

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[o:/o]<|=- dogtor@projectorheaven.com.au
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