Film-Tech Forum ARCHIVE: Damage to the SR.D track

This is topic Damage to the SR.D track in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

To visit this topic, use this URL:
https://ft-forum.com/ft/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=1;t=006240

Posted by Chris Byrne (Member # 1563) on 06-03-2004, 07:22 PM:

Forgive me for my ignorance, as I have a couple of questions relating to damage to the SR.D track.

1. Is the SR.D track printed on emulsion (as in picture) or base side of film (or both)?

I ask this to see if I can rule any factors out as to why a print might rise from say 2's and 3's in the first week to 5's and 6's after 4 weeks of play.

2. (Excluding LED / Soundhead performance), what are the most common problem areas which would cause a rise in a feature's digital error rate?

I am under the understanding that a rise of 1 in the error rate over a 12 week period (i.e. 4 to 5.) is the maximum a print should climb in an efficient .

EQUIPMENT used _ Kinoton FP30D projectors, Cinemmeccanica CNR3-35 Platters.

Posted by John Pytlak (Member # 331) on 06-03-2004, 08:58 PM:

ALL of the soundtracks are printed to form an image on the emulsion side. Severe abrasion on the emulsion side can actually remove chunks of one or more layers of the emulsion. But abrasion on EITHER side of the film can refract and scatter light or generate dirt particles that will increase the bit error rate of the Dolby Digital or Sony SDDS tracks. If you know you are severely abrading that area of the film, determine the cause and fix it.

Of historical note, 35mm and 70mm prints with MAGNETIC sound have the magnetic oxide coating on the base side of the print.

Posted by Stephen Jones (Member # 16) on 06-03-2004, 09:08 PM:

G'day Chris, If you have the skate set wrong you will cause abrasion on the SR.D track.The recomended setting is 2 thickneses of film on the intermittant.I have mine set a bit more about 1mil just enough so u can move skate up and dowm very slightly yet still be tight if you know what i mean.Guys at Atlab pointed this out to me recently and it will also reduce the wear on the Skate as well.I find the black type of skate seems to be more abrasive than the white nylon type which I understand you cant obtain anymore [Frown]

In regards to the platter are all rollers turning freely?also is payout adjusted as with my expierence with Cinemaccanica platters if it under feeds the film tends to drag around the rollers on the payout module.I find that with recon prints we recieve from the States the SR.D tracks seem to be worn in some cases and tend to start to fail after a couple weeks.With new prints it tends to last as we have had new prints at the end of thier season still reading low on about 2, when they first started they were reading 0-1 which is acceptable.

Cheers,
Steve [beer]

Posted by Michael Barry (Member # 237) on 06-03-2004, 11:43 PM:

Chris,

Check the entire film path after a session to check for any kind of excessive buildup or shedding, which is usually a giveaway as to where the problem might be. If everything is riding smoothly, then gate tension could be the culprit.

Another way to find ideal gate tension is to back it off while the film is running. When it starts to jitter in the gate (if you can perform this without an audience, so much the better), then nip up the tension just enough so that it doesn't. That is the perfect tension setting for that print.

One more word of advice: FilmGuard! Using filmguard will ensure that your DD error rates not only stay the same over time, but actually decrease! At the Randwick Ritz, we ran 'Moulin Rouge' over 300 times, and when it left the theatre, it ran 0's and 1's. When we received it, it was on 3's and 4's - no kidding. It achieves this by pulling off the dirt that gets in the way of a good read. You'd be surprised how much dirt there is on a NEW print, let alone a second hand one. Contact Ray Derrick at Panalogic, the Australian distributor for FilmGuard, and have a chat, then talk your boss into it. You'll never look back.

Posted by Paul G. Thompson (Member # 655) on 06-04-2004, 12:09 AM:

As far as I am concerned, Stephen Jones is 100% correct. The SR-D and SDDS tracks really catch hell because those tracks (when moving) are coming in contact with a stationary steel part.

If a hunk of crystalized wax or debree is present on the "skates," (as Stephen puts it) that crud can and will destroy a SR-D or SDDS track in one pass if that crud build-up is bad enough.

The DTS Time Code Track does not come in contact with the skates so it will fare much better.

Film Guard will reduce the damage to the SR-D and SDDS tracks. But the best thing, in addition to the use of Film Guard, is to keep the film traps, guides, skates, and rails clean!!!! If they are worn out, replace them. Don't use bubble gum to patch the super glue. Bad business.

Posted by Michael Barry (Member # 237) on 06-04-2004, 12:51 AM:

I agree with you, Paul. I did forget to add that the runners may be worn and might need replacing.

Of course, if FilmGuard is used, then the runners and film path WILL be clean! [Big Grin]

(Sorry, couldn't resist!)

Posted by Jack Ondracek (Member # 1466) on 06-04-2004, 01:47 AM:

I know this is no record, but we've had as many as 6 weeks out of a print with no SRD error increases. What the print & trailers start at is almost always what they end with when we ship 'em out.

We FilmGuard all our prints, which just might contriute to this somewhat! [Big Grin]

Posted by Ken Lackner (Member # 1002) on 06-04-2004, 11:10 AM:

quote: Paul G. Thompson
If a hunk of crystalized wax or debree is present on the "skates," (as Stephen puts it)....

Actually, Paul, Chis is running Kinoton projectors. Skate is the proper term for what most other projectors call the gate. [Smile]

Posted by Chris Byrne (Member # 1563) on 06-04-2004, 05:22 PM:

Thanks Guys,

All our gate tensions are set at 2 to 2.5 increments for a normal print (if there is such a thing.)

The bands have little to no wear (checked daily) and the skates (black) are adjusted to 2 thicknesses of movement (1 with film laced in projector.)

I bought a bottle of film guard off my own bat, however was told I could only use it to rejuvenate old ads if I couldn't get replacements, so I am a bit limited in that aspect.

I do find that if a print is shedding (leaving purple dust), I can use a cue tip (cotton bud) to rub a lining of film guard over the bands and lands of the skate.

I have added a set of washers to fit inside the sensor post on all projectors, as I noticed that the base side rubs on this quite significantly.

My other concern is that a couple of our payout units have one roller that isn't spinning consistently. It is the metal flange roller that sits on an angle feeding to the first platter roller. I ordered some new spindles in for these, however there must be some tolerance issues, as one of the two spindles I ordered was too large to fit into the roller.

Thanks for all your assistance [Smile]

Posted by Antonio Marcheselli (Member # 373) on 06-05-2004, 06:34 PM:

Chris

Actual prints are not the best I've seen but on a well maintaned projector the SRD track has no problem. I run an excellent copy of "Bruce Almight" for 10 weeks and the SRD error rate was 1.5.

Check physically the print. Do you see any damage that can be seen with your eyes?
I run Cinemeccanica projectors but I've been told that Kinotons are very gentle with prints.

About CNR's I can just say to be aware to the grey roller that is on the center feeder on the platter. It has to spin freely when the film is running.

Bye
A