Film-Tech Forum ARCHIVE: Christie AWM3's brain problem

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Posted by German Marin (Member # 918) on 01-20-2002, 03:58 PM:

I'm working with 4 AW3M platters. I have a problem on one of it: when the platter is taking the film (middle platter) the brain doesn't let the platter stop until I remove the brain or turn off its switch (If I don't do this the platter still running and the arm will crash against the platter's motor). Maybe it need calibration on the mechanism where lie the brain but I'm not sure about what's the problem.

Posted by Aaron Sisemore (Member # 145) on 01-20-2002, 04:57 PM:

First thing you need to check is if it happens with a different brain. If changing brains fixes the trouble, then check to make sure that the feed arm on the 'bad' brain is not bent causing it to hit the rollers as the swing arm reaches toward the motor.

If changing brains does not cure the problem (however you say removing the brain does cure the trouble) then mechanical adjustments and.or timing adjustments are in order.

This is a common trouble with fixed-brain AW3s.

-Aaron

Posted by German Marin (Member # 918) on 01-20-2002, 05:45 PM:

I tried to use the brain in another platter: the other brain from same platter, same problem. I changed with other platter (change from auditorium #2 to #3) still the problem, however It work fine in the platter of auditorium #1. How can I calibrate the brains? in the bottom of it i can see a pin and a screw...The problem was fixed by easy way but I would like to know how to fix it without change brains....

Thank you very much Aaron I'm to far from the city and the way to came here is to long for technicians. (I really feel like in family with all you, my teachers!)

Posted by Jim Ziegler (Member # 86) on 01-21-2002, 01:48 AM:

I have this problem all the time. Most likely, you have a broken piece on the takeup arm. To check this, remove the entire take up arm assembly (4 bolts) and pull it out. On the inside of that assembly is a white piece which is basically a hook to move the light filter to a stop position. You problem is, most likely, that this hook has either broken or bent out of shape. Replacing them is tedious, but not overly difficult. I believe the part is called a "clamp-lever". I have been told that, if you don't want to do the repair yourself, you can "repair-exchange" the entire assembly.

Posted by German Marin (Member # 918) on 01-23-2002, 12:47 AM:

Jim, I will try to do what you say, I'll repair it. Thank you for help me to fix the problem

Posted by Brad Miller (Member # 2) on 01-23-2002, 01:18 AM:

I'll try and be a bit more clear and talk in as plain of English as I can here. (I've never had to remove the actual arm assembly on the side of the arm to fix this.)

Turn off the power to the platter.

Remove the brain.

Remove the platter deck (it just pulls straight up, but it's easier if you pull the motor back from the edge of the deck first)

Remove the two screws holding the end cap of the arm on.

Remove the screw underneath the end of the arm, next to the platter work lamp. Notice that this will free up the led assembly inside. Now you can remove the led assembly completely by just unplugging it. (This will be obvious.)

Get a flashlight and look in there. While looking inside the arm, move the takeup arm back and forth and see if it isn't catching. This will be very obvious if it is.

At this point there are two ways for you to go. (Since you noted that removing the brain solves your problem, you can bet you need to go with the second option, but I offer it here for other viewers.) First if NOTHING is binding, odds are you have a motor speed control card that has gone crazy. Try swapping the card with another deck for verification (but put them back where they were when you finish troubleshooting or you will screw up the speed timing). If that doesn't work, which I doubt is the problem in your case, try swapping the led assembly with another known good one (I'll explain how in a minute). Now if you DO see two parts binding, read on.

Once you see where it is binding, remove the 4 bolts just above the end of the arm where the platter axle is and with a bit of careful maneuvering, you will be able to pull the entire assembly out of there. Do not force! You must angle it a little bit one way and then another for it to come out.

Now that you have the axle out of the platter's arm you can do whatever needs to be done. Sometimes I see the two little black flat posts that stop up against the screw (located on the underside of the axle) have been bent and simply bending them back straight will solve your problem. Sometimes the problem is more severe and you can wrap 1/2" masking tape around the second post (the one that comes into contact with the screw when the axle is at rest) to in essence "extend" that just enough so the arm will not bind. Other times you can loosen the allen screw that holds the light filter (clear plastic moon shaped piece with black marks on it) and raise or lower it just a touch so it will not bind.

Basically once you get in there the problem should be obvious and a few minutes of common sense will get you fixed. I've yet to actually see a situation where the part was physically broken, but as Jim points out I have heard of it. You can always compare another arm to this one to verify if anything is broken. Good luck.

Posted by Jim Ziegler (Member # 86) on 01-23-2002, 02:20 AM:

You have better luck than I do, Brad... We manage to break one of these every couple of months..

Posted by Brad Miller (Member # 2) on 01-23-2002, 04:35 AM:

Next time you have one break on you Jim, see if anyone at the theater has a digital camera you could email me a couple of pictures of it. I'm actually curious as to how they are breaking. Like I said, you are not the only person who has reported this, I've just not seen it yet.

Posted by Jim Ziegler (Member # 86) on 01-23-2002, 02:26 PM:

Basically, all that is happening is that the "hook" part is breaking off from the rest of the part. I know our sister theatre breaks quite a few too, as I have to give them some occasionally...