Film-Tech Forum ARCHIVE: Preview Whirr...

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Posted by Andrew Bangs (Member # 4938) on 11-01-2008, 10:58 PM:

Hello... I have an interesting case of a whirring noise but only during particular Previews. I am assuming this is the preview and not the projector although it could be a combination of both as we just noticed this problem and we just moved it to a new projector. Any Ideas??? Can this develop while the print is being run over two to three weeks?

Posted by Monte L Fullmer (Member # 2797) on 11-01-2008, 11:02 PM:

Any specfic areas of the machinery that you can pinpoint this "whirring" noise to?

Kinda need more specifics to help you out on this one. Sorry...

Posted by John Wilson (Member # 269) on 11-02-2008, 03:03 AM:

Does it sound like the sprocket holes catching on the sprockets?

Posted by Andrew Bangs (Member # 4938) on 11-03-2008, 12:23 AM:

Ok sorry I meant that their is a whirring noise comming through the speakers.

Posted by Andrew Bangs (Member # 4938) on 11-03-2008, 12:24 AM:

But now that you mention it I have noticed a buzzing coming from the Dampening Sprocket. not on this particular film but on others that also comes and goes with different previews. Sometimes If I squeeze the clamp on the Dampening sprocket I can get the noise to go away and I also see the film shift it's tracking laterally by a minute amount. but I never see any film dust in the projectors so I know it is not scratching the film. I figured just bad film.

P.S. sorry for the double post... My connection has been funky lately.
[dlp]

Posted by Monte L Fullmer (Member # 2797) on 11-03-2008, 12:54 AM:

Are we talking about the sprocket after the INT sprocket, or the final holdback sprocket after the scanner drum?

K, sounds like the sprocket itself is beginning to have hooking problems as the base of the teeth. Any way to take the sprocket out and reverse it to begin the wear on the opposite side of the teeth?

What kind of platter system do you have?

Posted by Richard Hamilton (Member # 321) on 11-03-2008, 03:13 AM:

Andrew,
I just had a nice long conversation with the projector company in Harbin and your theater came to mind. We decided that your problems are not equipment related, but rather operator error [Razz]

Just kidding. She was interested in hearing about your problems.

What sound format are you playing your trailers in?

Rick

Posted by Mark Strube (Member # 4190) on 11-03-2008, 11:50 AM:

It this in a DTS or a DD house? (Or neither? Both?)

If it's DTS, have you monitored the DTS player to see if the whirr happens when a given trailer must run in SR or SRD?

Posted by Michael Brown (Member # 890) on 11-03-2008, 02:30 PM:

It could be an SRD house where everything is fine in digital but the SR is picking up the DTS track.

Posted by Monte L Fullmer (Member # 2797) on 11-04-2008, 12:46 AM:

True, he does have basement SRD readers attached to that thing. It's quite easy for a lateral guide to come out of adjustment just a hair and the optical reader picking up that timecode.

If he can do the adjustment to that lateral guide, any loop of film with DTS timecode can act like buzz track in a way - for one side can be the audible uneven squall buzz of timecode and the other side can be the steady sprocket buzz.

It's a band-aid fix if one doesn't have any genuine buzz track test film.

Posted by Andrew Bangs (Member # 4938) on 11-04-2008, 12:57 AM:

quote: Richard Hamilton
What sound format are you playing your trailers in?

Rick,
We are trying to run everything in Dolby digital but this particular projector (along with two or three others) is playing in Reverted Optical (aka Analog). The problem only occurs when the sound is reverted but for all the previews the sound is reverted only a couple have the Whirr. We have tried to re align the digital head as best we can however without the proper equipment it is a Crap shoot. It used to be as easy as looking for the Green LED on the camera mount but those have long since been responsive. Yet we can still have digital output. Just the other day a reader that usually pops between Digital and Analog due to faults in the digital around 6/7 (without any adjustment) was reading digital with 1/2 faults which I have never seen here (usually around 3/4). But still the LED on the Camera Mount was red. I am to the point of calling in a witch doctor because this just looks like VooDoo to me. Any help you can pass our way would be most appreciated.

I love movies and I love the movie experience which is what I want to share with the people of our city. But every sound flip, stoppage, Brain wrap, Flicker of the screen just tears my heart as I have to go in and say I am so Sorry to these people that their Movie experience was ruined.

quote: Mark Strube
It this in a DTS or a DD house?

It's a DD.

Monte we are using Horizon Platters. Right now however Two are down and we have some old Strongs replacing them but the problems are consistent. right now our plan of attack is Getting all the platters up and running. then we are going to tackle sound issues. In the Mean time I am just looking to get a head start on diagnosing the issues so later the fixes will come with less wasted time on trouble shooting. and if their is something simple that can be done in the short term well then I will do it. Thanks for the suggestion of flipping the sprocket I think I can do that. I will run a test and let you know.

Again thank you all for the response. This has truly been an invaluable resource for for me. [thumbsup]

Posted by Monte L Fullmer (Member # 2797) on 11-04-2008, 01:54 AM:

quote: Andrew Bangs
we have some old Strongs replacing them

At least, those STRONG A(P)3 units are simple to operate and they can be very dependable.

quote: Monte L Fullmer
one side can be the audible uneven squall buzz of timecode and the other side can be the steady sprocket buzz.

..and forgot to add that when you don't hear any one of these two sounds, you're pretty well dead center of the optical track.

Posted by Michael Brown (Member # 890) on 11-04-2008, 08:42 AM:

quote:
We are trying to run everything in Dolby digital but this particular projector (along with two or three others) is playing in Reverted Optical (aka Analog). The problem only occurs when the sound is reverted but for all the previews the sound is reverted only a couple have the Whirr.

This does sound like it could be picking up the DTS timecode, if some trailers have the "whirr" and some don't, then some trailers have timecode but some don't.

Posted by Andrew Bangs (Member # 4938) on 11-05-2008, 01:46 AM:

I think I may have figured out some of the problem today. Their is a rocker arm that straddles the sound drum and while readjusting it today for the umpteenth time I noticed the film was tighter to one side than the other so I removed the Arm completely and the two arms were not parallel to each other. A quick squeeze and they were back in alignment (at least to the naked eye). I then replaced it and the film ran smooth. Unfortunately after that it did not run the rest of the night (as no one bought to it) so I will have to wait and see what happens the next time it runs. I am just keeping my fingers crossed on this one.