8mm Forum: Chinon C-300 judder problem

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Posted by Warton Parfitt (Member # 1730) on September 23, 2009, 10:24 AM:

I have a Chinon C-300 Dual gauge silent machine in almost new condition in the original carton with instructions. Unfortunately when projecting film there is an intermittent audible judder visible on the screen at about 1 second intervals.It occurs on both gauges with film that is perfectly OK on other machines. I wondered if the sprockets were loose on the shafts but found that not to be the case. Has anyone any ideas ? [Confused]

Thanks.

Posted by frank arnstein (Member # 330) on September 23, 2009, 10:03 PM:

Hi Warton
I recently serviced 3 of these projectors so I remember them well.
Have you made sure the film gate, claw tip & all associated parts are spotlessly clean? These parts are difficult to get to, so they often are left by their owners to build up dust & other debris till they wont play properly.
I would suggest you spray an evaporative spray all down the film gate, aperture and side guide rails. Then a light spray of lubricant & a careful wipe down. Look for a fluff ball on the claw tip & flush off if there is one.
Try it out again & let us know if that makes any difference.
See if it is able to maintain a good loop both top and bottom.
Tell us if it looses any loops when it judders.
Good luck with it.
dogtor pufferfish
[Smile]

Posted by Warton Parfitt (Member # 1730) on September 24, 2009, 05:31 AM:

Thanks for the quick response. I have now tried that & no improvement ! There is a momentary slight loss of loop causing film to touch the loop-former every second and it is this that causes the noise.I have also tried WD40 on the sprockets and brushing them.The fault appears on both gauges , forward and reverse and in normal & slow motion ( though in that case at about every 4 seconds).The cyclical nature of the fault made me suspect the sprockets but now I am not so sure since they seem to rotate about twice a second. Still baffled [Confused]

Posted by John Whittle (Member # 22) on September 24, 2009, 11:03 AM:

This sound a lot like a claw that isn't going deep enough into the film perforation so occassionally it missed and drops a frame. I'm not familiar with this machine, but see if you can manually advance the film and then try it with multiple pieces of film in the gate and see how many it will pull at a time. In the case of the 16mm Eiki, the claw protrusion should pull 6 pieces of acetate film in manual advance.

I don't know if there is an adjustment for this or not. With a new in box projector that's 20 years old, lubrication can turn hard and it might not let the cam follower move close in as it should. But it sound like a claw protrusion setting now to me.

John

Posted by frank arnstein (Member # 330) on September 30, 2009, 05:01 AM:

Hi Warton & John,

I have got a Chinon C-200 here in front of me.
It has been sent in because it has a judder in forwards project. If it drops a loop while projecting it won't respond to the loop resetter, but it runs Ok in reverse.

After a very thorough look at this very clean looking machine, I discovered that it has a bowed film pressure plate. These are a light plate & can be easily bent or bowed.
I suspect its had the lens holder slammed shut at some stage & it wont sit flat in the gate as its distorted now.
Easy enough to straighten in your fingers and check against a rule to make sure its flat again.

Make sure the claw tip retreats just beneath the aperture plate surface, before resuming its upward travel. Observe it by hand rotating the shuttershaft. If it needs adjusting for more depth, a small pair of screws holds the shutter to the shuttershaft.
If you loosen them, the shutter can then be slid along the shuttershaft to give more or less claw penetration into the film.

Let us know whether you find anything amiss or awry..

dogtor pufferfish [Roll Eyes]

Post Operative report Sunday 4th on the Chinon C-200.

After straightening the bowed pressure plate, the faulty loop restorer is now functioning again beautifully. No more judder at all. The picture is sharp and it projects well at all speeds & in both directions without loosing a loop during a whole 400' reel.

Yippee.....

I have conquered this beast by using my brain & feel very satisfied over the victory. Hope you win too.

dogtor pufferfish
[Wink]

[ October 04, 2009, 07:46 AM: Message edited by: frank arnstein ]

Posted by Warton Parfitt (Member # 1730) on October 06, 2009, 05:50 AM:

Thanks for all these tips and advice. After some delay at getting at this due to family health problems, I have now had another go.No improvement ! I agree lubricant could set hard after so long, so cleaned off the cam and used first penetrating oil and then machine oil. Also used WD40 on the works side.Had pressure plate out and could detect nothing but a slight bowing - soon rectified.Could not move shutter forward as it appears to have gone as far as it can.I also noticed drive belt was slightly loose and when removed noticed it had developed a kink but replacing with new belt made no difference.What puzzles is the regular 1 sec rythmic judder. I remain at a loss. [Confused]

Posted by frank arnstein (Member # 330) on October 08, 2009, 05:08 AM:

Hi Warton,
you say.....

"Could not move shutter forward as it appears to have gone as far as it can."

The shutter must be able to move further forward on its shaft.
Its held in place by 2 tiny grub screws on the hub, so loosen them both then slide the shutter forwards. It must move if its loosened properly.
If you slide it forward too far, the claw will jam, so be ready to slide it back again if needed. Marking its position with black felt tip pen before you move it will make it easier to do slight adjustments. Rotate & recheck the claw tip penetration before locking the grub screws.
It could take hours of careful work to get it right but don't give up till you do.

Once you have it moving on the shutter shaft, its a matter of getting the claw to penetrate the film sprocket holes deep enough.
Yet it must completely retreat to below the level of the aperture plate before moving up for another pulldown.
I set them up by eye & then rotate film through manually.
Adjust sideways if needed by using the eccentric cam near the claw pivot.

As for the 1 sec interval between juddering, try applying some grease to all the Spiral steel drive belts behind the rear cover. They deliver drive to the spindles.
If they are too dry, they won't slip properly on their hubs, causing a judder as the belt finally slips. It should be smooth slippage. So try lubing them.
Not too much though or it may not rewind full reels properly.

Give it another try and report back with any progress to us here in the forum.

dogtor pufferfish [Roll Eyes]

[ October 08, 2009, 10:44 AM: Message edited by: frank arnstein ]

Posted by Warton Parfitt (Member # 1730) on October 13, 2009, 06:24 AM:

Thanks for further advice.I suspect components of my machine not identical to some others.By not being able to move shutter forward I mean it was almost as far forward on the shaft as to be touching the bearing housing.Also the shaft does not protrude rearwad beyond the shutter itself.However on further inspection I note the whole shaft and shutter move backwards from the bearing at the point in the cycle where the cam begins to move out the claw.This now appears to be the cause of the original sympton.I then noticed that when this occurs there is a judder on the helical gear buried inside the works at the other end of the main shaft (front). Whether this causes the shaft to move backwards or is itself caused by something else I cannot say. In either evvent I think dissmantling the gears at that end would be beyond me ! [Confused]

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