This is topic Gate Focus problem on Century Model C Projector in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.


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Posted by Mark Farr-Nash (Member # 4233) on 04-29-2007, 05:15 PM:
 
New Guy with probable New Guy Problem:
I'm still getting my feet wet, but I've got a recurring problem with one of my projectors: the picture randomly goes out of focus when the reel change passes through the gate. It doesn't do it on every splice, but it will do it on the same splice from show to show. Then it will mysteriously change splices and go out of focus there for a couple of shows. It's driving me nuts. I thought it was a splice issue, but I've checked them all and they appear to be clean and not-too-big. Am I overlooking something really simple?

Thanks in advance,

Mark Farr-Nash
The Vernon Plaza Theater

[ 04-29-2007, 09:06 PM: Message edited by: Mark Farr-Nash ]
 

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Posted by Monte L Fullmer (Member # 2797) on 04-29-2007, 05:43 PM:
 
Welcome to Film-Tech ... what kind of projectors do you have for starters since there are so many variants of gate procedures per each machine to really pinpoint down your problem. So, let's begin there for starters then we can get down to the nitty-gritty of things.

..it's just like taking a car to the shop - mechanics need the make and model to get an idea of what to do ..

good luck - Monte
 

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Posted by Brad Miller (Member # 2) on 04-29-2007, 05:44 PM:
 
Read the rules before you post again. You have some repair work to do on your first post or you will be banned. #7 should be of specific interest to you.
 

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Posted by Monte L Fullmer (Member # 2797) on 04-29-2007, 05:48 PM:
 
(Yes, change your topic to "gate focus issue", or on that same line - make it more definite..)

..little help here...
 

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Posted by Paul Goulet (Member # 297) on 04-29-2007, 07:22 PM:
 
haha. i love how new members are welcomed here so warmly.....
 

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Posted by Mark Farr-Nash (Member # 4233) on 04-29-2007, 09:07 PM:
 
Sorry, should have realized.

It's a Century Model C, serial number C-9877. Is that what you're looking for?

Mark
 

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Posted by Carl Martin (Member # 1146) on 04-30-2007, 05:04 AM:
 
is the gate tension setting (the knob at the top of the operator side of the trap) on that machine higher than on your other machines? it could be compensating for an incorrect gate closure, resulting in too little contact between the gate rails/bands and the film, which is what holds the film flat (well, curved) in the gate. a splice going through could upset a delicate balance and change the focus.

that's the problem we were having a while back, anyways.
 

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Posted by John Wilson (Member # 269) on 04-30-2007, 05:09 AM:
 
Has it been doing this long? Does it do it on every film you play in that theatre?

Perhaps the gate runners are too close together and a slight difference in the film width (albeit small) is making the film buckle in the gate but not on every reel.

Just a thought.

Welcome to Film-Tech, BTW.
 

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Posted by Gordon McLeod (Member # 33) on 04-30-2007, 06:18 AM:
 
The century C typically has two versions of the straight gate
the older one has the top of the pressure skate curl backwards
the other it just stands upright like a fork
there are two gate tension knobs and they should be set close to the same
Also I have often seen buildup at the base of the studioguides cause focus issues
Also closely watch the splice go through and see if the film is twisting between the base of the trap and the intermittent sprocket
 

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Posted by Mark Farr-Nash (Member # 4233) on 05-01-2007, 09:14 AM:
 
Good suggestions, all, and thanks for the welcome.

My gates curl backwards like sled runners on both projectors. I watched the splice go through the gates, and it's definitely what's screwing it up. It also will get jittery when the manufactured seam goes through (is that what it's called? My vocabulary is still building).

I'm getting my booth serviced this Thursday, and so I will make sure that the tension is even on both ends of the gate.

Thanks again. I am positive I'll have other (correctly worded) questions in the coming weeks. Your combined expertise is much appreciated. I've already learned heaps just perusing the forums.

Mark
 

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Posted by Mark Gulbrandsen (Member # 72) on 05-01-2007, 10:10 AM:
 
You have the solid curved gate in your C Model. These are notoriously difficult to adjust and get right and is why Century eventually abandoned them. The biggest difficulty is getting the runners aligned with the curved skate. It is possible but can be time consumming...also don't take them apart unless you are well aware of how to re-align them again... and if they are badly worn they are all the more difficult to align properly. I'm not sure if Wolk even has parts for those any more. If they were my machines I would look for a pair of used model SA curved gates and traps and get rid of the old stuff, the SA gate automatically compensates as parts wear and takes splices much better than the old gate assy does.

Mark
 

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Posted by Gordon McLeod (Member # 33) on 05-01-2007, 07:15 PM:
 
Mark if it curls backwards towards the lamphouse it is a original straight gate century
The solid curve gate was in the H and retrofitted to C machines but I have never seen the pressure skate curve backwards
 

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Posted by Tim Reed (Member # 137) on 05-01-2007, 09:16 PM:
 
One thing to make sure your tech does: loosen the studio guides and shove them apart as far as they'll go, then lock them back down and forget about them. I'd also suspect emulsion build up on the trap rails, like Gordon said.
 

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Posted by Mark Farr-Nash (Member # 4233) on 05-02-2007, 09:12 AM:
 
Thanks again, all. I'll pass these bits along to my technician, and hopefully he can make all of the necessary adjustments. The good news is, everything will be running like a top when we premiere Spider-Man 3!

Best,

Mark
 

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Posted by John Hawkinson (Member # 1135) on 05-02-2007, 11:56 PM:
 
Tim said, "One thing to make sure your tech does: loosen the studio guides and shove them apart as far as they'll go, then lock them back down and forget about them."

I think we should be very careful giving advice that boils down to "modify the projector in a way the manufacturer does not intend." I believe there was an extensive thread on this topic at some point in the past, and several good justifications for making this change were offered. But it's probably a mistake to offer this kind of advice without the justifications...it can potentially cause confusion and misunderstanding.

Just my opinion...

--jhawk
 

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Posted by Steve Guttag (Member # 268) on 05-03-2007, 11:03 AM:
 
In this case John, the advice is good for all applications.

Steve
 

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Posted by Mark Gulbrandsen (Member # 72) on 05-03-2007, 11:18 AM:
 
Actually John.... Tim is correct on this post ... But the best thing to do is to completely remove those guides... but don't throw them away as the tech may need to use one of them to set the gate depth(on an SA). Not only do they do absolutely nothing they also make cleaning the trap very difficult. Removing them in every case has also improved lateral steadiness since the film is not bouncing off the rails. I rarely leave them on and cleaning things gets to be alot easier.

Mark
 

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Posted by John Hawkinson (Member # 1135) on 05-03-2007, 11:21 AM:
 
I see I was unclear...I wasn't suggesting it was wrong to remove them. I was trying to say that I think it's important to say WHY. Sorry about that.

So, why is it good to remove the studio guides? What changed such that their presence became a liability, or was it just a bad engineering decision?

--jhawk
 

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Posted by Scott Norwood (Member # 30) on 05-03-2007, 12:09 PM:
 
Should they be removed on SAs, too? And how does one use them to set the gate depth?
 

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Posted by Mark Gulbrandsen (Member # 72) on 05-03-2007, 02:38 PM:
 

quote: Scott Norwood

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Should they be removed on SAs, too? And how does one use them to set the gate depth?

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quote: Steve Guttag

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On straight gates, the studio guides form the stop for the gate mechanism.

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quote: Mark Gulbrandsen

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Actually John.... Tim is correct on this post

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...but not on any others?
 

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Posted by Mark Gulbrandsen (Member # 72) on 05-04-2007, 07:22 AM:
 

quote: Tim Reed

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...but not on any others?

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quote: Louis Bornwasser was the last to post

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Spreading them is good enough for me

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