8mm Forum: help with projector problem

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Posted by John C. Martin (Member # 2962) on February 22, 2012, 09:51 AM:

I am new here, but have worked with super 8 film since the early 70's. My problem is with a projector I have. it's a Keystone dual 8 with variable speed. I was using it to transfer my films to dvd. Literally overnight, the film will thread ok, but the picture is jumpy. Similar to when you need to push the loop former to stop it, but that doesn't work. I have cleaned the gate and film path. It's not the film itself because it does it with any movie. I am baffled. Can anyone please help? the projector works and has worked fine up until now.

Posted by Janice Glesser (Member # 2758) on February 22, 2012, 12:30 PM:

What is the specific model number of your projector? Many of the dual variable speed Keystones were made in Japan, so they have different designs then the ones made in the USA. There may not be a generic answer to your problem.

Posted by John C. Martin (Member # 2962) on February 22, 2012, 12:34 PM:

It's a Keystone 2500 Variable Speed

Posted by Janice Glesser (Member # 2758) on February 22, 2012, 01:40 PM:

That model looks very much like the Chinon 4000GL. Perhaps someone with a similar machine can provide some assistance. I know I was having a similar problem with my Sankyo. I was able to rotate a little rubber ring in the lower loop former, which did help. I'm sure it's not the same on the Chinon...but you might want to look in that area for any problems.

Posted by Jon Addams (Member # 816) on February 22, 2012, 02:31 PM:

John,

Your projector is not keeping the loop and the fact the loop restorer is not working points to a damaged section.

The Keystone 2500 is a clone of the Chinon 2500, except it has more plastic parts. You may have a pressure assembly problem as that section is mostly made out of plastic which tends to warp with the lamp's heat and nothing short of replacing it clear the issue.

There may also be a pull-down pin issue relating to proper penetration, or misalignment or both. It is difficult to find out which of these issues is causing your problems without first repairing one or the other (pin or pressure).

Jon

Posted by John C. Martin (Member # 2962) on February 23, 2012, 04:47 AM:

My thoughts were also that it was a problem somewhere with the loop or pressure on the film gate. I have run the projector with the front off so I can see what's going on, and pushed, pulled and held the loop restore mechanism by hand with no fix. The only glimmer of hope there is that for a split second the film stops jumping, but only for a second and then back to jumpy.someone mentiond a band, I do not see any kind of band on the loop restore. Only a metal arm and a spring. I have since purchased a new projector, but still want to fix this one if at all possible. I do appreciate all the comments and help.

Posted by frank arnstein (Member # 330) on February 23, 2012, 06:16 PM:

Hi John

I would check the claw penetration into the film. Sounds like it could need more depth into the film to prevent constant loss of loops. So you may need to loosen the grub screws in the shutter-hub and slide it forward just a whisker.

Good luck with fixing it.

dogtor frankarnstein
[Smile]

Posted by John C. Martin (Member # 2962) on February 24, 2012, 05:00 AM:

I also failed to mention, that the film doesn't "jump" like it normally does when the loop is gone, but it's rather like the film is rushing past the gate at a fast speed, to the point that you can't make out the image. There is also no clicking noise that normally happens when you lose the loop and need to push the loop restore. The film is at it's normal noise level, pretty quiet. It's as if each individual frame isn't being allowed to project before moving to the next frame giving it motion. Instead it's a blurred, constant image. Does this make sense otr complicate things?

Posted by Jon Addams (Member # 816) on February 24, 2012, 08:31 AM:

First, make sure the pressure plate is closed, at times I have forgotten to close it after cleaning.

If the plate is closed then, as Frank suggested, check the grub screw on the shutter, loosen it (you will need an Allen wrench) and slide it forward just a bit at a time testing it as you go.

If this doesn't solve your problem than you may have a bent or broken claw.

Jon

Posted by John C. Martin (Member # 2962) on February 24, 2012, 09:04 AM:

I know the gate is closed, so I will look into the shutter as you suggested. thanks.

Posted by Hugh Thompson Scott (Member # 2922) on February 24, 2012, 02:53 PM:

Hi John,not being familiar with this make of projector, but your
very good description of the fault leads me to think the claw is broken.Is there an inching knob that can be rotated by hand
so that the action can be observed to see if the claw is making
contact through the gate.If this can't be seen or even felt protruding, then I fear the claw has been damaged.

Posted by John C. Martin (Member # 2962) on February 25, 2012, 05:06 AM:

Hugh,
For my own understanding, is the "claw" you refer to something that is located near the film gate that passes through the sprocket holes and helps pull the film through the gate? Is it accessable and can it be repaired or replaced? How do I get to it? Is it something I could repair?I have a framer knob if that is what you mean by inching knob. Other than that I don't see anythng else. Thanks for the help

Posted by Andrew Long (Member # 2134) on May 05, 2012, 04:28 AM:

Hi,

I have a similar problem. Ran a film through a Cinerex 727 and due to a bad leader it rolled itself around the bottom cog. Managed to free it but everytime I play a film it now looks as though the film is wizzing through to quick and the frames are not visable.

Help!

Checked all the teeth in the cogs, film gate is shut and everything looks normal.

Cheers

Andy

Posted by Martin Jones (Member # 1163) on May 05, 2012, 04:37 AM:

This sounds suspiciously as if the bottom sprocket (Cog) is pulling the film through continuously. If so, you have damaged the claw which pulls the film through the gate. This results in the film not stopping on each frame; the bottom loop is lost ( and possibly even the top one).
The projector will thread normally because the loop formers guide it through properly. Once they are released the loop disappear.
On that machine the claw is a single very thin pin. You should be able to see it from inside the lamphouse.

Posted by Andrew Long (Member # 2134) on May 05, 2012, 04:51 AM:

Thanks. Is the pin an easy part to replace?

I will take a look tomorrow, but what you describe makes sense.

Thanks

Andy

Posted by Martin Jones (Member # 1163) on May 05, 2012, 05:11 AM:

In my humble opinion (and I do most of my own repairs on many different items I own) NO.
This one is very similar to the claws fitted in Eumigs. There does not appear to be a source of suitable spares, so it's down to the extent of one's expertise in dis-assembly, fabrication and fitting of a new part and re-assembly.
Not a job for the faint-hearted and probably much more satisfactory to obtain another complete machine... the Cinerexes are very common and pretty cheap.
Martin

Posted by Andrew Long (Member # 2134) on May 05, 2012, 05:18 AM:

Martin,

Might use this one as a donor for parts when I buy another.

Thanks for the advice.

Andy

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