This is topic Oscillating AW3 takeup troubles :( in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.
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Posted by Aaron Sisemore (Member # 145) on 03-16-2001, 10:59 PM:
OK... I have two AW3s in different locations that have the same problem: The awing arm refuses to remain steady and begins to oscillate. Sometimes to the point of the take-up disc coming to a complete stop at the maximum inward limit of the swing arm's travel (nearest the tree). Both these platters (as are all of the AW3s I service) are timed to the Film-Tech anti-print-throwing specs, and both the offending decks feed perfectly fine. What can this be? I have a couple of theatre managers that get very nervous when the disc starts to oscillate...Brad? Bevan? Anyone? Thanks for the help!
Aaron
Posted by Aaron Sisemore (Member # 145) on 03-16-2001, 11:04 PM:
Additional info: Only a single deck on each of the offending machines is oscillating. All the other decks work perfectly.-Aaron
Posted by Darryl Spicer (Member # 711) on 03-16-2001, 11:20 PM:
It has been a while since I worked with aw3's Could it be the three cards that controles the speeds for each funtion going bad. Maybe one of the little turn pots becoming defective. Did you try switching the card with one of the other cards to see if the problem moved.
Posted by Aaron Sisemore (Member # 145) on 03-16-2001, 11:56 PM:
I haven't tried swapping motor controller cards yet. That will be done monday when I service one of these theatres, as well as any other suggestions.-Aaron
Posted by Adam Martin (Member # 641) on 03-16-2001, 11:59 PM:
It's been a while, but I recall there's a problem that develops over time with the photocell or it's light source that controls take-up speed. It's located in the arm under the platter. Of course, Christie could've re-engineered the whole darn thing by now. 
Good luck.
Posted by Randy Stankey (Member # 64) on 03-17-2001, 03:19 AM:
Christie has reengineered the photocell units. You can now get ones with phototransistors in them instead of CdS cells.You'll have to replace the LED adjustment card as well, but once you do timing is a snap and they hold their timing a whole lot better. All you have to do is set the payout arm at 100% and set the motor speed control so the platter does 25 RPM. I like them a whole lot better.
Once I eliminated timing problems and possible malfunctions in the speed control cards I'd be looking in the area of the LED/CdS units. Either check for dirt and crud built up inside or replace the whole unit. If that didn't work, I'd look to make sure the take up arm and it's associated linkages moved freely. (ie: No caked-up grease in the joints, etc.)
Posted by Brad Miller (Member # 2) on 03-17-2001, 05:04 AM:
Some of the green leds exhibit this problem. Change them out and the problem will go away. It seems to be completely random, but fairly rare. If that doesn't solve your problem, change out the speed card, although I've only once had that as the culprit.Be careful on the newer design linear light filters. The ones I used were magnificently smooth in their operation from 20% to 100%, but had a nasty "bump" between 0-20%...which is precisely where long 2 1/2 hour+ movies will start to slide around. (Christie may have already fixed this minor design glitch, so it may not even be an issue at this point. The filters I got were manufactured about nine months ago.)
Posted by Steve Guttag (Member # 268) on 03-17-2001, 08:46 AM:
Since you say it is only the take-up that has the problem....
Look at the feed fingers....do they track with the take up arm SMOOTLY? Are they hitting anything in their travel (when in take-up).
Presumming that is ok....take the Take up arm assy out (the whole thing comes out via four mounting screws)...there should be a white nylon pawl (aka finger) is it there? Is it damaged? Does it move freely? Is it's return spring doing it's job (it is a little compression spring that resembles a ball-point pen return spring). If any of the above has a problem, it will cause the problem you describe.
A quick way to check without pulling the take up, is to swing the takeup roller towards the column and then try to move the feed fingers back towards "0"...you should feel the spring pushing back without ANY slop.
Finally, the ball bearings on the payout spindle (both removable and non-removable) may be binding, especially if crud has fallen down into them.
Steve
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"Old projectionists never die, they just changeover!"
Posted by Paul G. Thompson (Member # 655) on 03-19-2001, 09:21 PM:
Aaron, I think you have a motor control card ready to take a vacation.