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Topic: Oscillating AW3 takeup troubles :(

Aaron Sisemore
Flaming Ribs beat Reeses Peanut Butter Cups any day!

Posts: 3061
From: Rockwall TX USA
Registered: Sep 1999

posted 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

Aaron Sisemore
Flaming Ribs beat Reeses Peanut Butter Cups any day!

Posts: 3061
From: Rockwall TX USA
Registered: Sep 1999

posted 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

Darryl Spicer
Film God

Posts: 3250
From: Lexington, KY, USA
Registered: Dec 2000

posted 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.

Aaron Sisemore
Flaming Ribs beat Reeses Peanut Butter Cups any day!

Posts: 3061
From: Rockwall TX USA
Registered: Sep 1999

posted 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

Adam Martin
I'm not even gonna point out the irony.

Posts: 3686
From: Dallas, TX
Registered: Nov 2000

posted 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.

Randy Stankey
Film God

Posts: 6539
From: Erie, Pennsylvania
Registered: Jun 99

posted 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.)

Brad Miller
Administrator

Posts: 17775
From: Plano, TX (36.2 miles NW of Rockwall)
Registered: May 99

posted 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.)

Steve Guttag
We forgot the crackers Gromit!!!

Posts: 12814
From: Annapolis, MD
Registered: Dec 1999

posted 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

------------------
"Old projectionists never die, they just changeover!"

Paul G. Thompson
The Weenie Man

Posts: 4718
From: Mount Vernon WA USA
Registered: Nov 2000

posted 03-19-2001 09:21 PM

Aaron, I think you have a motor control card ready to take a vacation.

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