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Author Topic: Scratch Problems Mike Lauber Film Handler Posts: 19 From: Fond du Lac, WI, USA Registered: Nov 2002 posted 02-21-2003 07:15 PM                     I'm having problems with scratches on two of my screens. They both are using simplex projectors and soundheads, with Potts Alpha platters. The scratches are appearing on the extreme right hand side of the screen. They are very thin continual black vertical scratches. I can't seem to track the source down. Any ideas? Mike  |  IP: Logged Brad Miller Administrator Posts: 17775 From: Plano, TX (36.2 miles NW of Rockwall) Registered: May 99 posted 02-21-2003 07:46 PM                     Most commonly that is your pad roller(s) being out of alignment. When there is film running, are the pad rollers spinning (they shouldn't be) and can you reach in and freely spin the pad rollers by hand? Have you inspected the film to verify if it is happening on the base side or the emulsion?  |  IP: Logged John Westlund Expert Film Handler Posts: 204 From: Burney, CA, USA Registered: Jun 2001 posted 02-21-2003 07:47 PM                     I have seen the same type of scratches you are describing. Im using a Century SA, RCA soundhead, and AW3R platter. Are you using any type of film cleaner and are you using film guard on it? The only other thing I can say is to check the alignment of all of your rollers. I did that and have been changing my cleaner pads more often and havent seen the scratch but it hasnt been very long since I did this. Im sure someone else will have some more ideas that may help us both. John Looks like Brad just beat me with his reply. I will check what he said when I go in tonight.  |  IP: Logged Brad Miller Administrator Posts: 17775 From: Plano, TX (36.2 miles NW of Rockwall) Registered: May 99 posted 02-21-2003 08:06 PM                     The second thing to check is your failsafe. The older style failsafes with the drop down "dog ears" were notorious for this. What kind of failsafe do you have? John, from his description I am 99% sure any film cleaner is not making those scratches and I am equally sure it is not the platter either. (Do make sure you remove those evil brain springs on your AW3 though.)  |  IP: Logged Don Bruechert Mmmmmmmmm, bird! Posts: 340 From: Manitowoc, WI, USA Registered: Jan 2003 posted 02-21-2003 08:08 PM                        We were having this problem when I first started. I went on a major cleaning mission (besides the toothbrush I use between every show) and I found that several of the pad rollers were tight and did not spin. I cleaned them all and lubed them up really good (don't remember the name of the stuff right now, but it was for that purpose). Now they spin free, but I didn't know about that alignment thing Brad said. I know they don't spin because I thought something was wrong because of that and that's what led me to find out they were tight - but they still don't spin.... Anyway, haven't noticed the scratches since I cleaned things up.  |  IP: Logged Brad Miller Administrator Posts: 17775 From: Plano, TX (36.2 miles NW of Rockwall) Registered: May 99 posted 02-21-2003 08:20 PM                     There are two arguments on setting pad roller clearance. Both agree that the pad rollers should spin effortlessly with one film's thickness on the sprocket (this does not mean they will spin during normal operation, just that they can be manually spun with a finger and 1 layer of film). However there is a split when it comes to whether there should be noticeable drag with 2 or 3 layers. Personally I set them so that there is a drag against the film with 3 layers. If you set it to 2 layers, every time a splice goes through you will basically be giving the pad rollers a "kick" and if you have any shedding going on, it will only stir up dirt at the reel changes worse than the gate will kick up. Also if you go back and run some acetate film stock, that film is thicker than today's polyester.  |  IP: Logged Jacob Huber Expert Film Handler Posts: 172 From: Evansville, IN, USA Registered: Feb 2002 posted 02-21-2003 09:23 PM                     We have this exact same problem going on with 5 of our projectors. The five in question are all Simplex XLs with SH-1000 soundheads and have either the Potts Aplha platters or the old Neumades (with the takeup elevators). There is only one other XL in the building, and it has none of this kind of scratching. The main difference is that this one is mounted on a 5-star soundhead. I just chalked up the scratching to being with the lateral guide roller on the SH-1000 soundhead. With the recommended "2 sprocket holes back off", there is some play that would allow the film to slide out and get caught between the metal of the LGR and the "corner" of the impedence drum. However, it could be our pad rollers, but then again, almost none of them spin right on any of our projectors, and we don't have scratching but on the 5 XLs.  |  IP: Logged Andrew Duggan Expert Film Handler Posts: 127 From: Albany, NY, USA Registered: Jun 2002 posted 02-22-2003 01:53 AM                        I'm using pretty much the same setup as the afrementioned for all of my houses, and I can only echo the same things that have already been stated. Check every guide roller for movement, and check all of their surfaces for any abrasions that might cause it. Also check your soundheads and the surrounding areas to make sure the film is going through without any sort of resistance or obstructions. Be sure to check the film path between the platter & projector as well, to make sure that the film isn't dragging on anything, like a sound rack, etc., on the way, since these platters are not exactly the crowned princes of keeping quality tension between platter/projector. Sorry to sound like a broken record here. Hope this helps you out.  |  IP: Logged John Westlund Expert Film Handler Posts: 204 From: Burney, CA, USA Registered: Jun 2001 posted 02-22-2003 02:08 AM                     Brad - The only thing that made me think possibly that the cleaner was doing it was that the scratch comes and goes and I thought I had checked everything. After what you said about the pad rollers that made perfect sense. I checked tonight and there is a roller in the soundhead that will spin sometimes and the it stops which could explain why the scratch comes and goes. I also realized that I havent noticed the scratch on the first run of the print which would rule out the cleaner anyway. Another thing I thought of that could possibly cause this on an AW3R is that if you havent put the washers under the rollers in the brain to raise the film up so that only the sprockets are touching the stationary guide bars. If anyone needs that procedure it is under tips in Christie AW3 Platter Tweeking. John P.S. I have removed the springs from the brains.  |  IP: Logged Brad Miller Administrator Posts: 17775 From: Plano, TX (36.2 miles NW of Rockwall) Registered: May 99 posted 02-22-2003 02:41 AM                     Not only adding the washers below the rollers, but make sure you don't have those evil 90 degree squared off rollers. Make sure you are using the ones with tapered edges. Otherwise if someone threads too fast you will lay a nice emulsion scratch on the projected right edge of the picture. (Almost always first degree "black" scratch.) I'll get some pics of this and post it next week. Hard to explain.  |  IP: Logged John Westlund Expert Film Handler Posts: 204 From: Burney, CA, USA Registered: Jun 2001 posted 02-24-2003 01:00 AM                     I tracked down my scratch problem this afternoon. Like Brad said it was on one of the rollers on the failsafe drop down arm. It had a bad bearing and was spinning and then hanging up. I changed the bearing today so time will tell. Thanks Brad. John  |  IP: Logged Chris Byrne Expert Film Handler Posts: 102 From: Kirwan, Australia Registered: Jan 2003 posted 02-24-2003 02:06 AM                     Michael, I had similar scratching, caused by slight burring on the flanged roller of the pay-out unit. Once you have narrowed down which cinema is to blame, focus on the film's thread path starting from the feed. Identify if it is base or emulsion scratching. Since you already know the scratching is happening opposite soundtrack - you have nullified a few variables already.  |  IP: Logged Dave Callaghan Film Handler Posts: 60 From: Toronto, Ontario, Canada Registered: Jan 2003 posted 02-24-2003 04:02 AM                     1) Another thing you need to check on pad roller clearance on a Simplex is the adjustment of an eccentric shaft pad roller. The 2 roller pad roller arms have an arm adjustment screw that sets clearance for the roller on the end of the arm. The other roller can be on an eccentric shaft - if you loosen the shaft screw, you can turn the shaft, and if it is eccentric, the roller will move towards and away from the sprocket. If things are really off, you may have to set the eccentric, then reset the arm adjustment again. 2) Thin black scratches sound like base side scratches, but it is worth verifying whether they are just on the base side or also on the emulsion side. Scratches could be happening at more than one place in the film path. To determine if the projector head or sound head is the source, you can run a loop for 5 minutes then check base and emulsion for scratches. If a pad roller is scratching, bear in mind that if you see a scratch on the right side of the screen, you are probably also picking up a scratch on the opposite side in the sound track area that of course you won't be seeing on screen. If the projector head and/or sound head turn out to be the source, the projector head pad rollers are on the base side. The pad rollers in a 5 Star sound head are also on the base side. If you have a sound head with a gear box / constant speed and hold back sprockets, the constant speed pad roller is on the base side. The hold back pad rollers are on the emulsion side.  |  IP: Logged System Notices Forum Watchdog / Soup Nazi Posts: 215 Registered: Apr 2004 posted 12-28-2004 06:51 AM                 It has been 673 days since the last post.  |  IP: Logged Carl Martin Phenomenal Film Handler Posts: 1424 From: Oakland, CA, USA Registered: Feb 2002 posted 12-28-2004 06:51 AM                        we've been plagued recently with scratches like these on 2 screens. there have been lots of red herrings but i think i've narrowed it to the pad rollers on the upper feed sprocket (century jj & msa). they both have flat spots which cause them to sometimes turn, and sometimes hang up in one position. a tech will be coming in to look at/replace these. now, i've seen here and heard from others that these pad rollers should not be turning while film is running (except possibly for splices), as the film isn't in contact with the roller. but the pad rollers close onto the sprocket at about the place where the film separates from it to form the upper loop, and it appears that, for at least part of the cycle of the loop, film does contact the roller. how else could a flat spot have developed? the pad rollers do clear by 2 film thicknesses or more. our upper loops certainly are not too small; any bigger and that jj loop really starts to flap around--though, come to think of it, maybe i should verify that there isn't somebody making the loops too small. anyways, any further thoughts on this are welcome. carl  |  IP: Logged

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