8mm Forum: How can deal with this "light problem" (ST1200)

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Posted by Winbert Hutahaean (Member # 58) on February 13, 2008, 11:02 PM:

I have 2 identical ST 1200s.

One is normal, but the other one has an issue on projecting the film. Everytime I played a movie which had a lot of dark scenes then some light from brighter objects would spill out to the dark area making such paths/lines (look at the below picture and the arrows given). It was really disturbing

How to deal with this?

First time, I thought it was the issue on lens. But when Idid swap between the other projector's lens, the problem was still there!.

What I haven't done is swapping the bulb, but do yuo think it is the problem?

thanks,

Posted by Brad Miller (Member # 2) on February 14, 2008, 05:05 AM:

I can't tell too well from your picture (a picture of the same image from the other projector would be a good comparison), but is that vertical smearing you are seeing? If so, it sounds like you have a hole(s) in your shutter.

Posted by Paul Adsett (Member # 25) on February 14, 2008, 10:00 AM:

I don't know about a hole in the shutter - seems unlikely, but it could be that the shutter is out of phase with the claw. If so, that is easily corrected by loosening the screws on the shutter and making the appropriate adjustment so that the shutter is totally blocking the aperture for the full down movemnt of the claw.

Posted by Graham Ritchie (Member # 559) on February 14, 2008, 11:47 AM:

I agree with Paul what it looks like is a bad case of "Ghosting" your shutter timing is miles out.

Graham.

Posted by Winbert Hutahaean (Member # 58) on February 14, 2008, 08:16 PM:

Last night, I changed the bulb witht he other projector... and the problem was still there!.

So this is not the bulb issue.

Paul, thanks for the input, due to my poor english and not a tech guy, can you give a picture (or other who has the inside picture) where is the part that I should fix.

thanks,

Posted by Brad Miller (Member # 2) on February 14, 2008, 11:00 PM:

Whoops, yeah that's right it is possible to have a shutter physically out of alignment with the claw on an ST1200. That is probably moreso what it is than a hole in the shutter. (Too much cinema work on my part.)

Posted by Graham Ritchie (Member # 559) on February 15, 2008, 02:21 AM:

Winbert
Just check the claw first, make sure you dont have a broken spring before doing anything with the shutter, does the film go through the projector OK? although the shutter timing is out its the "why" I have never seen a shutter come loose, anyway check your claw springs first.

Regarding the shutter and what it does, simply put, it stops the light from the lamp reaching the film and therefore the lens while the claw pulls the film down through the gate, this is from the moment the claw starts at the top until it is finished at the bottom. Once the film has fully stopped thats when the shutter allows light to pass through the film.

If light hits the film while its still in motion thats where the "Ghosting" image will come from. To quickly check your projector with it "unpluged" the lens holder swung open and with a magnifying glass slowly manually turn the projector in the fwd direction, watch the claw see what it does, and at the same time look through the aperture plate, so you can watch the shutter at the same time, both claw and shutter should work as described, well thats roughly what it does.

Graham.

Posted by James E. Stubbs (Member # 817) on February 16, 2008, 08:07 PM:

The second I saw that picture and descriptions I remember a section in my ST1200HD Service Manual on exactly what the problem is and how to fix it. See the attached scans on shutter/claw timing/alignment. Good luck. (Picture comming shortly.)
Cheers,

Posted by Winbert Hutahaean (Member # 58) on February 17, 2008, 09:46 PM:

James,

I am waiting for your scan, as I tried what Graham mentioned previously, it did not succed. I found that claws and shutter were working perfectly.

cheers,

Posted by James E. Stubbs (Member # 817) on February 18, 2008, 02:46 PM:

I couldn't get it to upload to save my life. I emailed it to admin to post but it's not been put up yet. I can email it to you directly if you'd like. It's instructions from the service manual as to how to properly align the claw/shutter and eliminate ghosting.
Cheers,

Posted by Winbert Hutahaean (Member # 58) on February 19, 2008, 01:10 AM:

Moderator...please!

Or James, you can also email me at winbert <at> hotmail.com

thanks

Posted by Kevin Faulkner (Member # 6) on February 19, 2008, 07:45 AM:

Any pic being uploaded will fail if the file size is bigger than 200KB or the Physical size is larger than 550Pixels in width.

If that criteria is applied you shouldn't get any problems uploading pics.

Your more than welcome to send me a copy of your file(s) and I will try for you.

Kev.
(super8 at mrelmo dot co dot uk)

Posted by James E. Stubbs (Member # 817) on February 19, 2008, 07:38 PM:

I made sure it was a jpeg and less than 200k and less than 500 pixles wide. It just came up w/ an internal server error. I've emailed the orignal tiff scan to you. In any case here's the instructions:
B-3, Shutter, (17)
Incorrect postion of the shutter; Shutter flows (Picture trails).
Flaws on shutter or deflection; Flutter
1. Attach the shutter to see that it covers teh aperture mask whenver the claw transports film. Refer to Fig.8.
2.After Attaching the machine frame to the projector, Check the shutter postion again as following procedure.
Load the filmand turn the motor knob to still projection.
Turn the threading knob in foward direction and observe a picture. In this case, it is nomal that the picture does not move. If picture moves just before going out, change the shutter postion in forward projection direction. If picture moves just after appearing, move the shutter in reverse projection direction. (They're reffering the the adjustments on the shutter held w/ three screws. Also can be rotated about axes of shaft to correct claw/shutter timing.)

Cheers,

Posted by Winbert Hutahaean (Member # 58) on February 19, 2008, 08:10 PM:

Thanks James,

I have received them and will post the pictures below for the benefit of others:

and this is the illustration:

Again thanks and I will try it tonight. Hopefully it will be fixed. I will keep you guys informed.

cheers,

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