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This topic comprises 2 pages: 1 2
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Author
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Topic: Nasty vertical scratch
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Thomas Dieter
Expert Film Handler
Posts: 234
From: Yakima, WA
Registered: Jun 2004
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posted 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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Thomas Dieter
Expert Film Handler
Posts: 234
From: Yakima, WA
Registered: Jun 2004
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posted 07-10-2008 09:14 PM
quote: Jeremy Weigel
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.
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?
quote: Jeremy Weigel
What kind of fail safe and platters do you use?
Need I quote myself about the platters.
quote: Thomas Dieter
We are using Christie AW3 Platters and Cinemecannica V-4s.
The failsafe is a generic National Cinema Supply Corporation inboard/outboard failsafe.
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.
I took again last night and ran a trailer pack multiple times through the projector and nothing has shown up. Only thing I did different was run the trailers through on a flat aperture, and then run them through a scope aperture. 6 passes latter, nothing showed. This is how intermittent it is and it's so frustrating.
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Jaime Tuzzio
Film Handler
Posts: 50
From: Salem, OR, USA
Registered: Apr 2008
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posted 07-10-2008 11:22 PM
quote: Thomas Dieter
We just recently have had a problem with one of our auditoriums scratching just about every print that is played in that auditorium.
quote: Thomas Dieter
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 spent months and months trying to figure out where a horizontal or slightly diagonal "platter" scratch was coming from as it never occured on or just after my shifts, so there wasn't anything I seemed to be doing wrong. At my prior two theatres it had never happened. When I'd think a pattern was developing (who built it, who's working projection, which house, etc.) everything would change. I tried mis-threading in every way I could imagine possible but could not reproduce the scratch anywhere. Tedious, difficult, and just plain annoying as it all was, I would only have welcomed whatever suggestions others had to try and stop the scratches. The damage was beyond embarrassing (we were the new theatre in town and everyone was coming to check us out) and replacing print after print after print took up time I would rather have applied elsewhere.
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