Film-Tech Forum ARCHIVE: Platter Problems

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Posted by William Phillips (Member # 1162) on 03-21-2007, 12:09 PM:

So this happened to me the other night. All ads and trailers went through fine, then on Dolby logo all hell broke loose.
There is no film in payout unit as broke the join to rey and sort it out.
Any ideas, Its got me stumpped.

Posted by Brad Miller (Member # 2) on 03-21-2007, 01:29 PM:

Looks like old sticky film to me. I don't see any actual tangling that wouldn't pull itself through, but it's just one picture from one angle.

Posted by Dominic Espinosa (Member # 2122) on 03-21-2007, 01:53 PM:

I saw something like that once with a single-sided splice on the logo trailer and sticky tape residue on the other side. Pulled another lap of film in, cinched tight, and with those lame brains the film can jump a roller and wedge the feed arm at full on infinitely!

Posted by Alex Cross (Member # 3520) on 03-22-2007, 12:20 PM:

Could be the potentiometer in the feed unit. When they're on the way out, it suddenly sends the feed unit into high speed. Does your alarm stop the platter?

Alex

Posted by William Phillips (Member # 1162) on 03-22-2007, 01:16 PM:

The platter carried on quite happy, projector also happy. It was just me that got scared so stopped and detangled it. Better safe than sorry.
Still a strange one, had many weird looking prints, turning to 50p`s, bulges etc but not this!

Posted by Alex Cross (Member # 3520) on 03-23-2007, 03:47 AM:

I can't really think of anything that wouldn't have pulled some film into the feed unit,other than the potentiometer. Static, adhesive, and odd bit of splicing tape would have tried to drag something through. I would imagine you've run that programe all week without any problems. I don't know of any tests you can do, short of changing the potentiometer, and they're £40-£90. The one thing I did find when mine started playing up, was that when lacing the film through the feed unit, moving the 'T' bar very slightly, the plate jerked, as if fast feeding. Hope this helps.

Alex

Posted by William Phillips (Member # 1162) on 03-23-2007, 05:09 PM:

Yea that print had played fine all week. No problems what so ever.
Swapped over the pay out unit to the other cinema and no problems in there at all.

Posted by Alex Cross (Member # 3520) on 03-23-2007, 05:56 PM:

If you find the problem moves to the other screen, then I would suggest replacing the potentiometer. I'd be more than happy to offer some form of assistance it that if you need it. Other than that, I can't really think of anything that might cause the initial problem.

Alex

Posted by Patrick Watkinson (Member # 4237) on 03-28-2007, 11:29 PM:

Wow, my very first post, I am so excited

William, I had a similar problem with a print. I think I see a similarity in where the problem occurred. You said it was at the Dolby Digital trailer portion of the film (and I recognize the acetate colour from the picture). My old cinema had ordered these little trailers to tag onto each film. They look cool and all but they have one problem: while manufacturing, dolby reels all of them on the “unconventional” way that prints are reeled onto collars. If you have been beside the platter system while the film reaches the first splice, you will notice that it has a tendency to curl in the opposite direction. I believe this, and perhaps some splicing tape resulted in your brain wrap.

My own experience with the darn Dolby trailers goes a little something like this:

It was the first showing of “field of our fathers” and I was on the floor in cinema #1 double checking the entire beginning of the print before the feature( all the corporate trailers, preview trailers and such). The film is now at the Dolby trailer, all is fine until it gets about 5 seconds from the end, the picture shifts upwards and then vibrates, and then the sound fails and I see the picture start to melt… Projector #1 alarm goes off, I dash upstairs…
- turns out, right at the splice, the dolby film had formed a loop and wedged itself in the potentiometer arm in the brain. After several wraps around the brain, this caused the film to jam, until the tension was great enough for the safety to engage and send the projector into alarm. Solution: remove the darn trailer.

Posted by Dominic Espinosa (Member # 2122) on 03-29-2007, 01:59 AM:

I highly doubt it's on acetate.
And the potentiometer is the extremely unlikely culprit.

The wind of the film is virtually irrelevant in this situation and a little Film-Guard will solve the issue.

Posted by William Phillips (Member # 1162) on 03-29-2007, 05:23 AM:

The dolby titler in question is 6years old(and still looking good). There is no curl to it whatsoever. It has been film-guarded for the last 5years.

Posted by Patrick Watkinson (Member # 4237) on 03-29-2007, 09:43 PM:

If the Dolby trailer is 6 years old I see no reason why it should have its opposition curl still in it (unless you have wound it back onto a collar in the “unconventional manner”. I am out of ideas...

Posted by William Phillips (Member # 1162) on 04-02-2007, 04:37 AM:

All my Dolbys get wound emulsion in onto 3inch bobbins.
Never had any curl problems with them. It takes a few weeks for them to settle down when they are new as they come in on stupidly small cores.