This is topic Finding the Source Of A Scratch in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.
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Posted by Bernie Anderson Jr (Member # 410) on 08-08-2001, 12:16 AM:
How do you guys go about finding a source of a scratch in just the picture head and sound head. I'm running reel to reel using Kelmar reel arms and I'm finding weird verticle scratched in more to the center of the film. It comes and goes but it usually is in the same spot. Bernie
Posted by Brad Miller (Member # 2) on 08-08-2001, 01:15 AM:
You need to be as clear about this as you can be.#1 What kind of projector?
#2 What color is the scratch? Do you know if it is on the base or emulsion?
#3 Does the scratch extend from the top to bottom of the picture frame?
#4 Is the scratch stationary, or does it move around? Is there a pattern to it's movement?
#5 Is the scratch vertical, horizontal, diagonal, and at what approximate degree of tilt? Is it curved?
Posted by James R. Hammonds, Jr (Member # 673) on 08-09-2001, 12:31 AM:
Try threading up an old trailer and run it for a few seconds, stop the projector, and check to see where the scratch starts.
That helped me find out where one of my projectors was scratching.
Posted by John Pytlak (Member # 331) on 08-09-2001, 11:20 AM:
Here's an article on preventing and diagnosing film damage:
http://www.kodak.com/US/en/motion/newsletters/reel/may97/scratch.shtml ------------------
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
Posted by Dennis Atkinson (Member # 345) on 08-09-2001, 05:48 PM:
I run a loop of white or yellow leader that has emulsion.
What ever is scratching it usually shows up with emulsion on it.Dennis
Posted by Bernie Anderson Jr (Member # 410) on 08-10-2001, 08:36 AM:
The scratching I seem to be getting is from I believe the sound drum. Now they are not scratches per say but very light "rub" marks. If you look close at the film and turn it just right to reflect the light and you can see very light scratching, not enough that it would effect the image, but what happens when you run it many times and all of that adds up? The lines vary in different sizes and they're not going completely straight, some are on a slight angle, but not horizontal. They only thing that this leads me to think is that it is something with the sound drum, The sound drum seems smooth enough, but not like the 5 stars that I have at work. When you look at the film at face value it looks mint. But I'm going the next step. Now, am I being too critical and crazy? The kinds of equipment I'm using are Super Simplex with a RCA 9050 with Kelmar reel arms.
Posted by John Wilson (Member # 269) on 08-10-2001, 08:40 AM:
If it was the drum, I doubt there would be any horizontal scratches from it.Are the scratches on the emulsion or on the base?
If the scratches are on an angle you should perhaps be looking at the platter or a roller where the film turns a corner.
------------------
"It's not the years honey, it's the mileage' - Indiana Jones.
Posted by Bernie Anderson Jr (Member # 410) on 08-10-2001, 08:54 AM:
No no no,no platter. reel to reel. Sorry! The sracthces are not horizontal but they're not straight either. They're various different light light scratches that aren't seen unless you look for them on the film. The reason I think that it has to do with the drum is that the same kind of lines that you usually see on a leader at started up are almost the same kind of lines that I'm talking about, but they're much lighter and like I said you have to look for them on the print.
Posted by John Wilson (Member # 269) on 08-10-2001, 09:03 AM:
How long are the scratches, Bernie? Are they quite small or do they continue for extended lengths?
Posted by Jerry Chase (Member # 660) on 08-10-2001, 09:20 AM:
By any chance does the upper reel case have the little arm with the wheel riding on the film that clunks against the case to warn for a changeover when the diameter of the reel gets small?
Posted by Harry Robinson (Member # 265) on 08-10-2001, 10:03 AM:
Bernie, your problem sure sounds familiar to me. I've been trying to find the elusive scratches ever since I got into this hobby. There are a couple of tips the guys have given me that have proved quite helpful for base-side scratching.
1. Change out your pad rollers to some nice new nylon ones.
2. Check for any kind of drag on your sound drum shaft. The thing should spin more than a minute by itself. Also check for crowning on the sound drum surface. If it's an old unit you may want to have it reground.
3. Check all your loops. There are a couple of places on almost any system where you can cause base-side scratching.
4. Do the virgin film test. That's how I isolated mine to the sound drum.
Good luck!
Posted by Brad Miller (Member # 2) on 08-10-2001, 08:36 PM:
John already asked this, but didn't get an answer, soooooo...Emulsion side or base side? This question really is crucial for assistance.
Also I'm not completely clear on the scratches themselves. Please try and describe them more accurately.