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Author Topic: Mysterious scratches Mike Beerbower Film Handler Posts: 12 From: Erie, PA, USA Registered: Feb 2000 posted 03-09-2001 12:28 AM                     I need some help tracking down the source of some mysterious film scratches. Four prints have gotten scratched in the past two months, all in a similar manner, and all in the same projector. The obvious conclusion is a mechanical problem of some sort, but we've been unable to find any physical cause for these scratches. There are two vertical scratches, right next to each other, that run throughout the print from beginning to end. They do not waver or stop. On the film, the scratches are about 7/16 of an inch from the inboard (opposite the soundtrack) edge. They're on the emulsion side of the film, but are light enough to appear black on screen instead of green or yellow. On the base side of the film, there's a vertical "band" of tiny horizontal scratches. This band is about 1/4 of an inch from the inboard edge, and is about 1/16 of an inch wide. Three prints have been scratched this way, but it never happens on the first run. We have Speco LP-270 platters, Century 35mm heads and soundheads, and Component Engineering FM-35 cue detectors. Anybody got any ideas? Thanks! Mike thespian99@hotmail.com Paul G. Thompson The Weenie Man Posts: 4718 From: Mount Vernon WA USA Registered: Nov 2000 posted 03-09-2001 01:00 AM                     Mike-What kind of projector and sound head do you have? Brad Miller Administrator Posts: 17775 From: Plano, TX (36.2 miles NW of Rockwall) Registered: May 99 posted 03-09-2001 02:05 AM                     Without knowing the specific type of projector and a picture of the damaged film, I'd say it's due to pad rollers. Make sure they spin freely with 2 thicknesses of film clamped between the pad roller and sprocket, but there should be a light amount of drag with 3 thicknesses of film. Also, make sure they have not developed rough edges. The newer pad rollers (say, the last 10 years or so) do not have the inside guide, but the older ones do and are notorious for making scratches once they become misaligned. Can you email me a picture or send me a damaged trailer I can take pics off of to post here for others to offer suggestions? Darryl Spicer Film God Posts: 3250 From: Lexington, KY, USA Registered: Dec 2000 posted 03-09-2001 02:50 AM                    You say that the scratches are not present on the first run. I am asuming that you are screening the prints and nothing is visable but on the next run you have scratches. If this is so then your scratch problem is somewhere after the film gate. With there being horizontal scratches on the base side check and make sure that the film is not running to close to the platter surface. If the picture area is running to close to the platter it can cause horizontal scratching. Also check and make sure that all the rollers are lined up correctly. Film should not be riding up on the flangs. Make a loop of film and thread the entire projector and sound heads. Turn motor on and allow to run for a minute. Unthread the heads and check the loop for any identical scratches. Tom Kroening Expert Film Handler Posts: 214 From: Janesville, WI USA Registered: Oct 1999 posted 03-09-2001 03:46 AM                     I'll have to agree with brad about the pad rollers.. make sure there arent any flat spots on them. Also, when testing for the location of scratching its probably best to use brand new trailer. Dont loop it but run run it to the floor for 10 - 15 seconds. Turn the motor off and unthread the film from the top down, carefully inspecting for where the scratches start. John Pytlak Film God Posts: 9987 From: Rochester, NY 14650-1922 Registered: Jan 2000 posted 03-09-2001 07:17 AM                        I would agree that for the vertical scratches, the pad rollers would be most suspect, and the fine horizontal ones are likely the film surface rubbing on the platter or riding up on a roller. Often there is a bit of debris near the site of the abrading "culprit", so if you find a roller that consistently has a buildup of emulsion, it may be the cause. In addition to running a "virgin" trailer and looking for where the damage starts, I'd take a close look at the entire film path from platter feed to takeup. Be sure all rollers are turning, and that the film isn't riding up or being pinched by something. ------------------ John P. Pytlak, Senior Technical Specialist Worldwide Technical Services, Entertainment Imaging Eastman Kodak Company Research Labs, Building 69, Room 7419 Rochester, New York, 14650-1922 USA Tel: 716-477-5325 Cell: 716-781-4036 Fax: 716-722-7243 E-Mail: john.pytlak@kodak.com Web site: http://www.kodak.com/go/motion Mike Beerbower Film Handler Posts: 12 From: Erie, PA, USA Registered: Feb 2000 posted 03-09-2001 02:43 PM                     Brad - pad rollers were the first thing we checked. No film-bearing surface on the roller is far enough in from the edge to cause these scratches. And to answer Darryl's question, the scratches actually may not show up for days or weeks after the print moves into that house. The film will look perfect for a while, then one day somebody will notice scratches running though the print. The scratching seems to be a random event that doesn't happen on every run, which makes it even harder to track down. Mike Beerbower Film Handler Posts: 12 From: Erie, PA, USA Registered: Feb 2000 posted 03-09-2001 02:44 PM                     Brad - if we can't find the cause over the weekend, I'll try to get a piece of damaged film to mail you. Brad Miller Administrator Posts: 17775 From: Plano, TX (36.2 miles NW of Rockwall) Registered: May 99 posted 03-09-2001 03:07 PM                     My next guess would've been the cue detectors, but since you have CE FM-35s, that's not the problem. Try and mail a sample and I'll get pictures and post them here. The address is on the "contact us" link at the bottom. Ethan Harper E-dawggg!!! Posts: 325 From: Plano, TX, USA Registered: May 2000 posted 03-09-2001 03:22 PM                     I would check to see if you have free spin on your soundhead and for other obvious causes such as knicks on the soundrum. I would almost wonder if the film is riding along the bar behind the takeup rollers. I would also check to see that the moveable takeup roller is aligned with with whichever platter is taking up. Are you using keepers? Are you making your loop sizes correct? These are just my guesses from out of the blue but without an visual aid of some sort that is all I can come up with. ------------------ --"That's my story and i'm sticking to it!"-- Tom Sauter Expert Film Handler Posts: 163 From: Buffalo, NY, USA Registered: Sep 2000 posted 03-09-2001 04:05 PM                        I'll second Ethan's suggestion, the sound drum. I have Centuries with Component Engineering reverse scan LED's installed and had vertical base side scratches. Turned out the drum bearing pressure spring gave up and the drum seized against the soundhead. Its a very very tight tolerance in there! Darryl Spicer Film God Posts: 3250 From: Lexington, KY, USA Registered: Dec 2000 posted 03-09-2001 06:05 PM                    That is why you need to make a loop and run it thru the projector heads. One pass is not enough. let it run for a couple of minutes. This will eaqual about a months worth of runs thru the head. If you see the comon scratches that you are refering to then the problem is in the heads if you do not then the problem is elsewhere. Believe me this works. The fly wheel should spin smoothly you should be able to turn it without it grabbing or feeling any resistance. Gordon McLeod Film God Posts: 9532 From: Toronto Ontario Canada Registered: Jun 99 posted 03-09-2001 09:02 PM                     First the emulsion only contacts the padrollers in a century soundhead. If it was a scanner (sound drum) problem there would be a lot of wow and flutter. I would bet on the failsafe or the platter. Straight lines usually come from rubbing on a non moveing part Paul G. Thompson The Weenie Man Posts: 4718 From: Mount Vernon WA USA Registered: Nov 2000 posted 03-09-2001 09:39 PM                     Check your film stripper on the intermittent sprocket. If loose and cocked, It'll scratch the emulsion side of the film. As mentioned, the only pad roller that comes in contact with the emulsion side of the film is the Century CS (or holdback, whatever you want to call it)sprocket. The rest do not in a Simplex, or RCA. If you are using proxsemity detectors in the cue detector/fail safe, check those, too. I have seen that happen just recently. Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 03-10-2001 11:40 AM                     Guys, The thing to do is order a SDS kit from ACE in Portland. This is called the "Scratch Detection System" and utilizes a special powder that floreses under a UV light(included in the kit). You take an old trailer and coat the film with the powder. Run it through the machine and look for a small pile up of powder glowing at the scratch point. Quite ingenious if you ask me. Mark @ GTS

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