This is topic Help needed determining a scratch origination in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.
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Posted by Cory Johnson (Member # 103) on 05-07-2001, 12:23 AM:
Pro 35 projector with a DTS reader mounted on top. I am 100% sure it is something on the projector itself, so I will leave the platters out of this. What is basically happening is we are getting a faint, vertical scratch(es) on the very right side of the film, (the side opposite of the sound track). Now, the projector has been doing this for as long as I can remember, however, it was never a big issue before because the size of the screen cropped it off so it was not noticeable. However, we got stadium seating and a bigger screen as of late and know the screen is the correct aspect ratio and the scratches are visible. I will try and describe them as best as I can.
- Only seem to appears after a couple of showings, but always "develop" over time.
- Once they are there, they don't really get any worse.
- Appear about a foot from the right hand of the screen on a descent sized screen (50ft ish).
- Are vertical and vary from a single, vertical scratch about 8 inches long to a bunch of smaller vertical scratches lined up very close to each other.
- Are patterned. What I mean is they appear in the same location on each film. Always towards the middle of the frame seems the worse.
- If you look physically at the film, you have to look VERY closely at it and you can see some "buff" marks at the spot of the scratches. Almost like a very light contact with a harsh object.
- I have tried a different film gate and it didn't change the scratch nor its characteristics.
- doesn't cover the entire film evenly, nor the frame evenly. Some reels you can't see the faint scratch, others it is very visible.
I have check every possible thing I can think of for this so any help is appreciate. Our techs don't know what could be causing it because all of the equipment looks good when inspected. Thanks in advance.
Posted by Joe Redifer (Member # 3) on 05-07-2001, 01:06 AM:
Making the bottom loop too big perhaps? Just a guess.
Posted by Randy Stankey (Member # 64) on 05-07-2001, 02:00 AM:
I second that guess and I'll raise you a "spitball". 
Posted by Darryl Spicer (Member # 711) on 05-07-2001, 03:26 AM:
ok here is a posability. two things could be happening first the pad rollers may be set to close to film. that would cause ones close to edge of picture.Second there is a roller between the intermittent sprocket and the lower feed sprocket of the projector head. check this roller for wear or for that matter go ahead and replace it this damn thing does not like to turn and can wear the roller down causing film the inner part of roller.
Posted by Dustin Mitchell (Member # 372) on 05-07-2001, 03:32 AM:
I had a very similar problem (still have occasionaly actually). Check the alignment of the upper and lower magazine rollers, the ones that feed the film to the platter. If these are not lined up perfect, the film can ride up on the edge of one of these rollers and this will cause exactly the kind of damage you are describing.
Posted by Brad Miller (Member # 2) on 05-07-2001, 04:04 AM:
Cory, I am reading conflicting descriptions in your post. At one point you said that the scratches are only visible now because you got a new screen and the edges are not being masked off like they were before. If this is the case, then all of the scratches should be on the right edge. This is most probably a pad roller scratch. They should be aligned so that the roller spins freely with 2 layers of film in between the closed pad roller and the sprocket, but the roller should not be able to spin with 3 layers of film.On another part of your post you mentioned "always towards the middle of the frame seems the worse", which seems to directly contradict your earlier statement about the masking and "appear about a foot from the right hand of the screen on a descent sized screen (50ft ish)". Please clarify so we can be of better help.
Posted by Joe Redifer (Member # 3) on 05-07-2001, 04:17 AM:
It is my guess that by "middle" he meant on the right side, but towards the center from top to bottom.
Posted by Brad Miller (Member # 2) on 05-07-2001, 04:23 AM:
Then if Joe read it correctly and the scratch does not extend completely from top to bottom of the projected image, it is either a loop scratch or an aperture scratch.
Posted by John Pytlak (Member # 331) on 05-07-2001, 06:27 AM:
Like the others, I vote for a loop scratch. Check those loop sizes.------------------
John P. Pytlak, Senior Technical Specialist
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Eastman Kodak Company
Research Labs, Building 69, Room 7419
Rochester, New York, 14650-1922 USA
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Posted by Aaron Sisemore (Member # 145) on 05-07-2001, 01:30 PM:
I KNOW you said that you don't think the platters are not involved, but I MUST know what platters you are using there?Aaron
Posted by Marc Jones (Member # 29) on 05-07-2001, 04:56 PM:
I have seen some thing simular on the older Potts type platter The film comes off the roller as the film goes onto the rewind platter.The scratches this would make were from one side and goes to center at a little bit of an angle, and it only take one time.
Posted by Joe Redifer (Member # 3) on 05-07-2001, 05:06 PM:
If I am understanding it correctly, the scratches are always in the same place on each frame. It does not move or wander. That basically eliminates the possibility of a roller scratch.Cory, are you using the same aperature as before, or was a new one cut when the new screen was put in? You say that the scratches were there before the new screen was put in.
Posted by Paul G. Thompson (Member # 655) on 05-07-2001, 05:41 PM:
Emusion side scratch? or non-emulsion side scratch?If it is a non-emulsion scratch, check the runner plate of the trap. It may have been dropped. Take the film trap out, and look for a "polished" surface on the curve that holds the intermittent sprocket shoe. It it is, chances are you found the problem. Very common with the Pro-35.
Just spring it back a little, and you should be ok.
If it is diagonal scratches on the emulsion side, the loops are probably too big and it is hitting the framing shaft, or that stupid roller the film lays on between the intermittent sprocket and hold-back sprocket. Take it off, shaft and all, and 99% of your emulsion scratches will go away.
I have taken all of mine off 15 years ago, and threw them away. The machine will run perfectly fine without them.
Posted by Darryl Spicer (Member # 711) on 05-07-2001, 06:38 PM:
I agree with Paul just get rid of that stupid roller between the intermittent sprocket and hold back sprocket. The older style pro 35's did not have these rollers if memory serves me correctly. What the hell they were thinking about when they added it is beyond me.
Posted by John Wilson (Member # 269) on 05-07-2001, 07:05 PM:
Cory,When you bypass the dts reader (when not needing to use it), does the film rub on the top guide roller of the dts reader? Even lightly touch it?
If it does (even more-so when it only just touches it,) that roller will not move and a 'green' print will see light scratches appear over time. dts readers are sometimes mis-aligned to the film path and use the fact that they are actually running through the reader to get 'on track', but when bypassing, the film is on another trajectory and this will put the right side of the image onto the roller.
That's my take...
Posted by Gordon McLeod (Member # 33) on 05-07-2001, 09:18 PM:
Do not remove the roller between the bottom of the intermitent and the lower sprocket. Excessive flutter in the sound will develop
THe problem is usually the wrong sized lower loop
Position the word Picture Start in the apperture and adjust the lower loop until the sound diamond is didectly across fromthe optical slit. If that is correc the lower roller will not cause scratching unless it is worn.
It was put there for a very important reason, just like it is there on the JJ
Posted by Tim Sherman (Member # 569) on 05-07-2001, 10:10 PM:
I just wish that you had this problem taken care of eairler. You said that with the old screen it was on you knew the scratches were there but didn't care because you couldn't see them. But don't forget these prints don't get shown in just one theater. so think about what happend to the next theater that received your scratched print. I know we have all had prints come in we needed to get replacements for, and it is alot more of a pain to have to go through , then it the film was taken care of at the previous theater. So all i am sayng to everyone is that if you are doing damage to prints get that problem fixed, and get it fixed fast. Most problems from scratches in my opinion are something that is very eaisly fixed without the need to call in a tech.
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Posted by Cory Johnson (Member # 103) on 05-08-2001, 12:03 AM:
I will try and answer as best I can. here goes:
Definitely not caused by a loop too big. I threaded it myself for the first 4 showings on a feature and the marking showed up.
Joe is right in that the "Middle" I mean the very right of the screen, but the markings tend to migrate towards the middle, and they always seem to happen the worse at the same spot: towards the middle on the very right side.
As far as the pad roller goes between the intermittent sprocket and lower feed sprocket, yes there is one there. Should I just remove it entirely? The sound flutter issue doesn't really apply(?) as the theatre has DTS.
I know it is not the DTS reader - it is less than a year old and the markings were there when the old one was in use. There were also times when we skipped the reader (non-DTS film) and the markings still appeared.
I believe it isn't the platters (Strong Auto programming platter), I am also on the same lines as Joe. If the markings are in a pattern, always at the same spot, it can't be a circular motion roller. I has to be something else.
I will check on the emusion side. I actually put a different film gate and shoe in the projector, but the markings still showed up.
Heres something else to consider: The projector actually froze up last Thurs (for no apparent reason) and we ended up having to have the intermittent replaced with a rebuilt, along with the usual coupler replacement to go along with it. Now, the marking appear further in on the film and are more noticeable. What could they have altered to cause this? Something in the alignment of the intermittent sprocket and shoe on the film gate?
We have been going around on this issue for years and we get no where because our techs don't know what to say because everything checks out perfectly on inspections. Yes, we have turned the blind eye for a while, but you are right that it is noticeable when moving the print to a different theatre. We are just hoping to throw the 35's out the window anyways and go with simplexes. The 35's are a large pain the ass along with our 1 remaining Xetron lamp house.
I will remove the roller as suggested, unless someone has a specific reasoning why not to. I will check the guide rollers, but am 99% that they are also correct. Keep the suggestions coming - hopefully we can nail it down to something... Thanks for all the input.
Posted by Joe Redifer (Member # 3) on 05-08-2001, 12:44 AM:
Replace every single component in the projector.
Posted by Paul G. Thompson (Member # 655) on 05-08-2001, 01:04 AM:
Gordon, Those rollers on the Ballentyne have caused more scratches than you can shake a stick at, even when they were new. Strong international FINALLY modified those rollers so that on pulldown, the film "cupping" will not come in contact with the center of the roller, which caused nasty horizontal scratches as the film slams against the center of the roller. Even the new ones raised cain with film scratching, but not nearly as bad as the older style. The newer rollers were cut out deeper in the center than it was on the edges. (It was not straight across).I was told by Strong International people that the only reason for that roller is to reduce loop noise, but that machine is still very quiet without it.
I have not noticed any change in sound flutter during tune-ups without that roller.
If the projectionist threads up his machine and the loop passes equally above and below the shaft hole by observation when the machine is inched forward, the lower loop will be the correct size. It isn't any bigger than a Brenkert or a Century.
The model VII Ballentyne soundhead is not the greatest soundhead in the world. Most of the flutter I have seen is caused by the scanner bearings being rough, the damper assy is shot, or there are major build-ups of crud and corruption on the timing belt pulleys or the belt tensioner, improper belt tension, a faulty timing belt, not to mention the friction "O" ring deterioration on the sound head stabilizer flywheel.
Other flutter problems were caused by the projector not running at a constant speed for one reason or another.
Posted by Brad Miller (Member # 2) on 05-08-2001, 04:32 AM:
Cory,Three things to test. First, take a brand new trailer and run it yourself without the aperture plate in the machine 8 times in a row (double what it took for the scratch to show up on a brand new print). If the scratch is not there, you have just found your problem.
Next, if the scratch is still there it sounds like either a loop scratch (from making the loop too big or too small). Try performing the same test with larger or smaller loops.
Finally, if that still isn't it, then I would look for a misalignment on the shoe or a rough spot. I can't think of anything else that it could be since you clarified that the scratches do not run continuously from top to bottom of the picture.
Posted by Gordon McLeod (Member # 33) on 05-08-2001, 08:06 AM:
Also with out that roller there is a far less steady image on the screen as a gen rule.
I have never had that roller cause a scratch in any of the pro35's we service.
Posted by Darryl Spicer (Member # 711) on 05-08-2001, 10:03 AM:
I have had that roller cause scratches do to the edges of the part of roller that the sprockets run across becoming worn. I replaced it with the newer typ of roller at the time. one question. Is the trap a straight gate or curved gate. Those straight gates have to be set tp allow just a piece of 35 mm film to pass thru with splice. if it is too close film will buckle a little.
Posted by Gordon McLeod (Member # 33) on 05-08-2001, 01:26 PM:
Even though the Pro35 trap looks straight it is actually curved. They copied the old Motiograph curved gate that curved the film laterally instead of the usual curve gate.
With out that lower roller it is not uncommon to have a unstable image.
Also because of the gate curvature it is not uncommon for a badly focused lamp to be the root of the problem causeing buckling that hits the apperture plate
Posted by Paul G. Thompson (Member # 655) on 05-08-2001, 01:38 PM:
Gordon is correct about the lateral curve in the gate. There are two gate gauges - a "77" and a "75". Using the wrong gauge in the wrong film trap will present problems.
It is not a good idea to change the intermittent sprocket without the correct gauge.
Unstable picture with or without the "lay-on" roller is common in the older machines because of a poor trap design, and the coupler bobbins are all hammered to shit because the outboard bearing was grossly mis-adjusted and made too tight, or the outboard bearing is shot.
The new trap Ballentyne designed is much more superior to anything they had.
Place your fingers on the outboard bearing assembly and start the machine. If you can feel it throbbing, the bearing and/or coupler is shot. Then, walk up to the screen, eyeball the picture, and you will probably see a slightly unstable image.
Posted by Joe Redifer (Member # 3) on 05-08-2001, 03:31 PM:
Man, if only we could see a short 1 second video of the projector manually advancing threaded up the way everyone always threads it. It would answer a lot of questions.It might be easier to run a film loop of something rather than an entire trailer. That way you can 100% eliminate the possibility that it is caused by the platter. You didn't answer the question about the aperature, though. Is it the same one you used before you got the new screen?
Posted by Cory Johnson (Member # 103) on 05-08-2001, 06:46 PM:
In answer to the plate: No, it is a new plate. Yes, the markings were still there from the previous plate. Will removed the roller and run some green preview stock through continuously to see what happens. Thanks.
Posted by Gordon McLeod (Member # 33) on 05-08-2001, 07:48 PM:
Dumb question
Does the roller have a flat spot on it?
look closely at the edges where the perf contact it
Posted by John Wilson (Member # 269) on 05-13-2001, 04:04 AM:
Take a piece of film you know to be scratched already and thread it in the projector. Take a close look at what parts of the projector touch the image of the print. My guys were saying our problem was a misthread on the platter, but I found it to be a light touch on the dts reader roller that did exactly as you are describing.