This is topic Nasty vertical scratch in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.


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Posted by Jon P. Inghram (Member # 4125) on 05-30-2008, 04:03 PM:
 
This morning I discovered that our print of Iron Man has been scratched rather badly:



The scratch is a set of uninterrupted dark vertical lines at or near the center of the screen that move left and right a bit at a frequency of maybe 2 Hz and slowly vary in severity, sometimes as obvious as in that drawing, other times barely visible. During the first show it there was debris scattered next to the lines as well, but that cleaned up after running Film-Guard on it. The scratch wasn't visible at the beginning of the trailer reel, and gradually became worse.

The platter is an AW3, the projector a Century SA with a Dolby Cat. 702 digital reader. The AW3 has the guide posts with the deep, beveled collars. Neither the projector nor the projectionists who worked yesterday are prone to scratching prints. The print is otherwise in excellent condition. The film is always soundtrack-up on the platter.
 

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Posted by Justin Hamaker (Member # 2165) on 05-30-2008, 04:17 PM:
 
I would think the film was not properly seated in a roller or there was some kind of foreign matter on one of the rollers or guides. Or maybe a barb on one of the posts around the brain.
 

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Posted by Jack Theakston (Member # 4484) on 05-30-2008, 04:23 PM:
 
Run some blank leader that is scratch-free through and inspect the results on the screen. While it's running, keep an eye out in the gate for the starting point of the scratch.

Also, check any rollers on your bench the film might pass through.
 

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Posted by Brad Miller (Member # 2) on 05-30-2008, 05:42 PM:
 
Is the scratch almost steady or does it wiggle from side to side noticeably at the same rate as a platter roller spinning?

Emulsion or base side?

Do you use the black or green rollers on your AW3. If green, do you have the metal keeper brackets with the white pegs, or are your keepers plastic and green?
 

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Posted by Jon P. Inghram (Member # 4125) on 05-30-2008, 09:12 PM:
 
Scratch is on the base.
Sometimes it fades to being almost invisible then suddenly gets worse again.
At the end of the credits it gets so bad you can feel the scratch on the print.
The print ran on that screen for over a week before it happened.
It weaves at a steady pace, I'm guessing maybe one and a half or two times a second, over a short distance (roughly the width of the scratches in the drawing I made.)
This AW3 has both green and black rollers. The black ones use the metal bar with the white pegs, the green ones use the big green plastic keeper that covers a quarter of the roller.
The guide posts (the two before the brain rollers and the two on the speed control arm) don't have any gouges or nicks that could have done that to the print.
I couldn't find any piles of film "crud" where it could have been scraped off at, but it's possible it could have happened on an earlier show and got cleaned without being noticed.

I'm guessing it was either just a misthread on the platter or maybe something sharp got stuck somewhere and fell out after the show dropped.
 

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Posted by Michael Wheable (Member # 3327) on 05-31-2008, 03:21 PM:
 
Looks like the same problem we had with our 702. The tension rollers closed when a splice went through one of the trailers, around 15 minutes into prog. Scratching didn't visually show up on screen until main film was on.
 

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Posted by Jack Theakston (Member # 4484) on 05-31-2008, 05:09 PM:
 
Slather it with FilmGuard as best you can.
 

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Posted by Randy Stankey (Member # 64) on 05-31-2008, 07:39 PM:
 
You have a Century SA projector and that has a glass window on the door to the sound head. Right?

Open the door to the sound head and look inside at the edges of the glass. I bet you'll find a chip out of the corner of the glass is missing.

What I think has happened is that a chip has broken off the glass and it fell down into the sound head and lodged there as the film was rolling by.

I've seen this happen on more than one occasion.

Do you have the FM-35 failsafe?

If so, the glass rolled down and wedged between the film and the edge of the failsafe. You might find the piece of broken glass on the floor under the projector.

This has happened on more than one occasion in booths where I have worked.

Here's the scenario:
1) The hinges on the sound head doors get loose because people slam them too hard.

2) The doors won't open and close correctly once the hinges come loose and the door link starts to break.

3) People start to slam the door harder and harder to get it to close.

4) After enough slamming, the doors are so beat that the glass starts to chip and break.

5) The chips fall down into the film path and destroy the film.

Solution: Remove the glass from the sound head doors on all your projectors. Or you could just take the whole door off. If you have changed all your projectors over to read or near-infrared LEDs you don't really need it anyway.
 

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Posted by Jon Cleary (Member # 4272) on 07-06-2008, 01:29 PM:
 
Been having similar marks with one of my simplex projectors running with an Alpha Platter system. Although the line/lines stay steady and don't weave and change in pressure. I have also gone for a couple of weeks without any marking at all. Talked to some Engineer friends and a couple of suppliers and we seem to have narrowed it down to the analogue sound drum not getting up to full steam or at least intermittently. Have ordered replacement bearings. Trouble being I have been given that many theories it's all spinning around in my head and wondered if any one else had come across the same problem/symptoms?
 

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Posted by Jeremy Weigel (Member # 4208) on 07-06-2008, 01:57 PM:
 
A common threading mistake with AP platters is to hook the film on the spring loaded hold pin on the take-up elevator instead of on the film guide that is just above it. This will give several vertical scratches at each point the film comes in contact with the spring coils.

For trouble shooting vertical scratches I usually thread the damaged film back up and stop it when the scratches appear on screen and carefully inspect each contact point of the film path paying special attention to where the scratches are in relation to those contact points. Vertical scratches most commonly occur because the film is being dragged over a stationary or almost stationary objection.
 

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Posted by Thomas Dieter (Member # 2507) on 07-09-2008, 07:58 PM:
 
We just recently have had a problem with one of our auditoriums scratching just about every print that is played in that auditorium. Only thing is, the scratches are intermittently happening. After a splice goes through, the scratch disappears, but ends up coming back. They are on the emulsion side, vertical, and waver on screen, sometimes going off screen. We are using Christie AW3 Platters and Cinemecannica V-4s.

I ran a test loop, about 13 seconds, for over 20 minutes and nothing showed up. I then ran 3 trailers through as a trailer pack on each deck. Nothing showed up until the 4 run.

1st Run was from Top Deck to Middle Deck
2nd Run was from Middle Deck to Bottom Deck
3rd Run was from Bottom Deck to Top Deck
4th Run was from Top Deck to Bottom Deck

On the 3rd run, the film started to jump vertically on the screen, but no scratches showed up on screen.

On the 4th run, the scratches showed up, emulsion side dead center of screen, and just about off center to the left (sound track side). I stopped the film, checked the take up and the scratches were on the emulsion side (black). I then checked the payout, and there were scratches there too before it went through the payout assembly.

I cleaned out the gate previously that night completely, and i checked it again there was nothing in the gate. I checked the aperture plate for any burs that might be rubbing on the film, and nothing. I've checked the failsafe to make sure that nothing is hanging loose. I've checked the entire film path and the only thing that touches the film where the scratches are showing up would be in the gate. Everything else runs on the sprockets or edges of the film.

What could be causing this?

--Tom
 

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Posted by Jeremy Weigel (Member # 4208) on 07-09-2008, 11:05 PM:
 

quote: Thomas Dieter

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I then checked the payout, and there were scratches there too before it went through the payout assembly.

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quote: Jeremy Weigel

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In order for you to have "black" scratches on the emulsion side, whatever it is is cutting fairly deep thru all 3 color layers down the base.

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quote: Jeremy Weigel

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What kind of fail safe and platters do you use?

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quote: Thomas Dieter

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We are using Christie AW3 Platters and Cinemecannica V-4s.

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quote: Thomas Dieter

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We just recently have had a problem with one of our auditoriums scratching just about every print that is played in that auditorium.

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quote: Thomas Dieter

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Having to stop the film in the projector would be very tedious, and seems like a waste of time. Inspecting all the way from the gate to the take up would be very difficult unless I un-thread the trailers.

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quote: Thomas Dieter

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From all the scratches that I've ever seen emulsion side, Black is the first color you get, followed by Green, Yellow, and finally White. Am I correct about this or are all my emulsion scratches going through the base and working their way through the emulsion?

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quote: Thomas Dieter

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Having to stop the film in the projector would be very tedious, and seems like a waste of time. Inspecting all the way from the gate to the take up would be very difficult unless I un-thread the trailers. I would take and lye down on the floor and watch the film pass over me as the film is running with a flashlight above my head, but the film moves to fast to catch the fine emulsion scratches that they start out as. Along with that, I don't know if it's in the projector or on the platter.

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quote: John Hawkinson

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And...your conclusion was?

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