Film-Tech Forum ARCHIVE: AW3 "Sparkle" Scratch mystery

This is topic AW3 "Sparkle" Scratch mystery in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Mike Olpin (Member # 1115) on 08-14-2008, 03:36 PM:

To the right of Norm, please note the tiny emulsion side "sparkles". The positioning is horiontally constant, but vertically random across the frame. This is not noticeble at all until about two days in to a run, but by the end of one or two weeks, it has become very distracting.

This only happens to prints we run from the platter. Changeover shows do not seem to be affected by this.

Each roller is spinning freely, and the film is riding between the flanges properly.

Equiptment:
Christy AW3, "V" style legs, plastic roller brackets.
Kinoton FP50D projectors
Kelmar media cleaner

Additional images of the film path:

*The wrap detector was removed as it was my first suspect, but the scratches continued...

Posted by Joe Redifer (Member # 3) on 08-14-2008, 05:24 PM:

What I would try is to build up a reel of junk film that has no damage. Run it several times but alternate the emulsion/base orientation on the first roller. If the scratch still appears in the same fashion, then that's not it. Get more new junk film. Try the next roller, then the next. You will eventually find the roller. Also check that each keeper is clean and smooth.

Posted by Scott Norwood (Member # 30) on 08-14-2008, 05:35 PM:

What is that round metal thing on the front of the sound head (just above the gate tension knob in these pictures)?

Posted by Brad Miller (Member # 2) on 08-14-2008, 06:04 PM:

Do you have anyone running soundtrack up on the platter BUT with the soundtrack away from the tree on takeup? If so, that's probably your problem. If not, I would take a look at the left white stripper roller in the brain for an abrasion. The fix in that instance is simply to loosen the screw and rotate the post a bit so the abrasive part no longer touches the film.

Posted by John Wilson (Member # 269) on 08-14-2008, 07:23 PM:

quote: Scott Norwood
What is that round metal thing on the front of the sound head (just above the gate tension knob in these pictures)?

It's a keeper. When the machine is stopped and the film loose around the drum, it keeps the print in the rollers above and below.

Actually, I don't think it does much good as I'm pretty sure the film would stay anyway and a few times I've thought of removing them to test that theory...but never have. I figure if Kinoton put it there, there must be a perceived issue.

Posted by Tim Asten (Member # 4051) on 08-15-2008, 06:39 AM:

That metal thing keeps the film in close proximity to the pulse reader which is normally fitted within the sound head cowling. You can see the hole where it fits. The Kinoton pulse readers are very accurate, hardly ever missing a pulse. Also they would not cause any film damage as the guide bar barely touches the film and even then only on the sprocket hole area of the film. It is hard to see if Mike's machines have them fitted though.

Tim.

Posted by Steve Guttag (Member # 268) on 08-15-2008, 07:18 AM:

It is actually a delrin piece, not metal. It should ONLY be on machines with prox cue sensors mounted in the soundhead. For non-automated machines (or ones with alternate cue detection), there should be no "skate" and a cover plate is mounted on the soundhead to cover the exposed hole.

The cue skate DOES wear and it is possible, especially with older films that have significant curl, to have the middle of the image rub the middle of the skate (it is a very deep recess but the film is not under any real tension there so all of the film's curl will be present...they should be changed if the film is coming close to rubbing in the picture area....they can be rotated once to pick up the "fresh" side.

Of course, the solution to this problem is to stop using the platter and just run on reels! [Wink]

Steve

Posted by Mike Olpin (Member # 1115) on 08-15-2008, 02:56 PM:

I've rotated the left stripper roller, however there doesn't seem to be any evidence of an abrasion on it. I will follow up with the other projectionists, but I don't think any of them are threading soundtrack out on the take up.

Posted by Brian Guckian (Member # 1678) on 08-15-2008, 05:02 PM:

As the film passes between the fixed posts immediately prior to the three rollers in the brain is it vertically centred, i.e. positioned so that the broad parts of the posts are clear of the picture area?

If the base of the posts are (slightly) contacting the film in the picture area, that could account for the scratching, which is happening on the non-soundtrack side and therefore would be running down side if the soundtrack is up as it passes through the brain.

IIRC the film position can be raised or lowered via shim washers (inserted under the rollers? - can't recall the details).

Posted by Brad Miller (Member # 2) on 08-15-2008, 06:13 PM:

I actually said that backwards, it would be the right post. Regardless, check the alignment like Brian wrote above in his first paragraph...and yes you can shim it with a washer or two.

Posted by Joe Redifer (Member # 3) on 08-15-2008, 07:38 PM:

Just adjust anything white in the brain to be safe.

Posted by Adam Fraser (Member # 1074) on 08-17-2008, 01:38 PM:

Do you work at the State Theatre Mike? I would guess they are the only ones with Kinotons and changeover capability in TC. Sorry to get off topic.

Posted by Mike Olpin (Member # 1115) on 08-31-2008, 12:31 PM:

Replaced the brain with a new one, problem appears to be solved. I think it probably was the striper rollers. the beveled area looked like it was too high. Thanks guys!

Yep, Adam, I'm at the State.