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Topic: Christie AW3 Take-up Issue

Thomas Dieter
Expert Film Handler

Posts: 234
From: Yakima, WA
Registered: Jun 2004

posted 11-19-2005 02:29 PM

Recently I have been having a problem with 2 of our platters, and they are both happening on the bottem deck. The take-up is not able to keep up with the feed out of the projector, and so the show drops. All the decks are timed exactly the same, for all of our platter systems,and by the same person. We are not having any other problems except with these two. Here's the symptoms and solutions that our tech has gone through.

Problems

Platter won't keep up with projector feed out.

Only happens at the beginning of the show, usually end after first or second rolling stock ad.

The motor has a harsh grounding noise.

Solutions Attempted

Tried moving motor to see if problem would follow. Failed

Tried making sure the sodor for the LED and the solar cell were good. Failed

Made sure drive wheels were still good. Looks Good

Made sure the Drive wheel rim was clean. Looks Good

Tried changing out LED/Solar Cell Assembley. Failed

Tried retiming the decks. Failed

If there are any other possible solutions that have yet to be tried, this would be helpful. Thanks in advance.

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Monte L Fullmer
Film God

Posts: 8367
From: Nampa, Idaho, USA
Registered: Nov 2004

posted 11-19-2005 02:52 PM

Hi Thomas - did you swap out the sensor assembly? They may look good, but they can get tired and start to short out. This happens many-a-times with these sensors, especially where you have the older AW3 unit.

Is the notch in the filter wheel aligned to the edge of the PE cell with the mark on the "0" degree position? - as mentioned in the manual?

Motor grind-brushes are tired or even bad. Take the brush caps off and inspect the brushes (which they shouldn't be bad since the motor's RPM is so low), or could be the bearings. Do a motor swapout in such case.

Timing factor - even though the book mentions (do you have a "platter tachometer") a certain RPM setting for the HIGH and LOW pots in the tower, you have to make your own settings at times for unit to operate correctly. Do you know how to properly time a AW3 with a VOM meter and the proper procedures that is listed in the manual?

little tips to help you out. thx-Monte

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Dominic Espinosa
Phenomenal Film Handler

Posts: 1172
From: Boulder Creek, CA.
Registered: Jan 2004

posted 11-19-2005 02:52 PM

What kind of grinding noise?
They sound something aweful when they're not receiving enough current to run, but creep.

Try swapping the make switch card or the LED card (the one with the 3 pots on it).
There's not much else it could be if the motors run fine elsewhere.

EDIT: Monte, you beat me to it!
Check what Monte said, however, the Hi/Lo pots shouldn't be at fault if it's dying on takeup.
However, on the subject of timing sometimes you have to trim the resistance way down, i.e. instead of 25k some of our platters run perfectly at like... 12.6k or so.
Why this is I'm not sure but that could be a factor as well.

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Monte L Fullmer
Film God

Posts: 8367
From: Nampa, Idaho, USA
Registered: Nov 2004

posted 11-19-2005 03:11 PM

12.6K ohm on the LED resistance? (OUCH!) Should be down to 70 (-/+ 2) ohms with the pointer on the 70 degree mark..and use a digital VOM meter.

-Monte

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Brad Miller
Administrator

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

posted 11-19-2005 03:11 PM

Sounds like the led below the axle to me. Swap that with the middle deck and see if the problem doesn't follow.

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Dominic Espinosa
Phenomenal Film Handler

Posts: 1172
From: Boulder Creek, CA.
Registered: Jan 2004

posted 11-19-2005 04:50 PM

quote: Monte L Fullmer
12.6K ohm on the LED resistance? (OUCH!) Should be down to 70 (-/+ 2) ohms with the pointer on the 70 degree mark..and use a digital VOM meter.

Word, it seemed weird to me too. Some of them run that way though. I really can't explain it.

Anyhow, to clarify, Monte's suggested timing practice is ala the Christie manual.
The process I was referencing was the FT AW3 tweaking guide.
Feed arm at full, resistance should be 25k.
With the exception of a few oddball systems.

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Monte L Fullmer
Film God

Posts: 8367
From: Nampa, Idaho, USA
Registered: Nov 2004

posted 11-20-2005 01:18 AM

Oh, okey after reading this section in the "tips" area, I can see where you're coming from.

Yes, the Ohms will be that high with the shutter disc fully in the open position.

But, the shutter usually isn't in this position during normal payout and rewind operation is why of the manual's recommended timing factors for a smooth and steady payout and rewind.

There can be more room for error using this alternative method since the recommended factors can point out more areas of concern in a more precise method and corrective measures can be used in such areas needed for a smooth operation.

This all comes from my years of working on vehicles with ignition timings using feeler gauges for point gap settings, strobe lights and dwell meters. Plus, in doing belt changeouts for overhead cam vehicles (and belt changeout on projectors): there is no shortcut in making things run smoothly.

One must follow proper procedures for the vehile to perform most effective and efficently. And doing platter timings of any platter make is exactly the same as I have mentioned above.

But, I guess if this alternative method works for some, then so be it.

Not for me to say what is right or wrong.

thx-Monte

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Thomas Dieter
Expert Film Handler

Posts: 234
From: Yakima, WA
Registered: Jun 2004

posted 01-08-2006 11:12 AM

Okay, our tech and myself have tried just about everything to see if we can get this problem fixed. We got the problem fixed on one, but the other is just not cooperating. We have changed out the Solar Cell Assembly, We have Swapped out the Solar Cell Assembly, we have swapped out cards, we've tried new cards, we swapped out motors. The problem doesn't follow to another deck or system, rather just stays there. The tech says that we've just about everything cept gutting the system of it's wires and rewiring it. I really don't want to do that.

What's really confusing is that you would think that the fix for one of our platters would be the fix for the other as they are having the same problem and same symptoms. The other platter that is now working just needed to have the solar cell replaced, and no problems have occured. What else could be wrong? I'm going to be gone to Marietta, GA to help at our location there. I plan on getting pic and sending them, but when I get back, I want to see if any of the solutions that you guys post might work.

Like I've said, we've swapped motors, swapped cards, tried new cards, swapped solar cell assemblies, tried new solar cell assemblies. The problem doesn't follow or go away. What to do?

BTW: The grinding noise that I was talking about happened to be the Drive Wheel. It had gotten to the point that it was starting to stick to the hub of the deck and that's what that noise was. We put on new drive wheels, and the grinding went away.

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Michael Schaffer
"Where is the
Boardwalk Hotel?"

Posts: 4143
From: Boston, MA
Registered: Apr 2002

posted 01-08-2006 11:24 AM

Maybe the platter hub or the three washers it sits on are worn or just too dirty. Did you check if you have the right washers? The think one on the bottom, then the bearing washer and finally the thick washer on top. It might help to clean all the parts thoroughly and regrease them.
Another thing which often happens with Chrirtie platters is that the pin inside the axle which keeps the brain from spinning gets loose and starts wandering outside, biting in the bushing on the inside of the hub.

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Louis Bornwasser
Film God

Posts: 4441
From: prospect ky usa
Registered: Mar 2005

posted 01-08-2006 02:45 PM

Sounds like you have changed literally everything. The one thing not mentioned is the wires going to the motor. Remember they loop up through the makeup pushbutton switch. Try exchanging one of these plug in switches for another on another platter. Louis

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Steve Guttag
We forgot the crackers Gromit!!!

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

posted 01-08-2006 03:47 PM

Okay...hang on a second there.

Put a payout head in the platter with the problem...

Take the take up arm and move it briskly but not in a jerking fashion back and forth...look at the feed fingers on the payout...they should be swinging and tracking precisely with the take up arm (note they will be swinging in the opposite direction as they do on payout).

If they done move smoothly and track precisely with the take up arm you have several potential problems.

The bearings in the platter spindle (not the big flat ones, the ones that allow the variable density disc to spin) may be binding. If it is binding at all...you will need to pull the spindle assy and clean (and possibly replace) the bearings and set the return spring tension.

The take up "pawl" may be bent/broken. Take the take up arm assy off from the arm (just for 1/4-20 screws) and inspect this white nylon finger. It should be free from damage (and be completely there). If need be, look at one of the platters that works to see what it should look like). Now, move the take up arm while holding onto its mounting plate. The nylon finger (pawl) should be spring loaded and it too should be moving freely and forcably back to its rest position.

Steve

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Mark Gulbrandsen
Resident Trollmaster

Posts: 16657
From: Music City
Registered: Jun 99

posted 01-08-2006 07:12 PM

I agree with Louis on this one [Cool]

check the make up switch assy. I replace about a half dozen of these a year for various reasons.

Mark

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Brad Miller
Administrator

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

posted 01-08-2006 07:23 PM

Louis and Steve both have good ideas, but so far there is one thing that no one has mentioned.

I have seen this happen because of an incorrectly mounted light filter, such that when the takeup arm is at 100%, the takeup platter isn't actually able to go 100% speed, whereas the payout CAN. Why wasn't this noticed years ago? Odds are whoever was running the platters timed them to "Christie manual specs", which are faster than they need to run.

The fix is to break off the set point "stud" (whatever it's called) on the bottom of the led/cell assembly and twist it slightly so that it lines up properly with the markings *or* (better solution) change out the light filter. The easiest way to test this is to move the entire axle to a different deck and leave everything else alone. (Yeah you could just time that one deck faster too, but that kills some of the accuracy in troubleshooting.) If the problem follows the axle, it's the light filter.

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Monte L Fullmer
Film God

Posts: 8367
From: Nampa, Idaho, USA
Registered: Nov 2004

posted 01-09-2006 03:06 AM

Is the platter level - both areas of front an back and left and right with a bubble level? Units with decks willing to pitch itself towards the front (and the lower deck is usually the culprit at times...as with STRONG and other makes) will do goofy things with the payout.

-Monte

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Thomas Dieter
Expert Film Handler

Posts: 234
From: Yakima, WA
Registered: Jun 2004

posted 01-10-2006 12:16 AM

quote: Michael Schaffer
Maybe the platter hub or the three washers it sits on are worn or just too dirty. Did you check if you have the right washers? The think one on the bottom, then the bearing washer and finally the thick washer on top. It might help to clean all the parts thoroughly and regrease them.

Right after I read this, I went into work and cleaned the washers and the Bearing Washer. Also made sure to clean the inside of the hub, and the shaft it sits on. Regreased it with just enough grease, not an uber amount, and the problem still happened.

Brad: there is one problem with your theory on the filter disk. The deck will stop spinning on payout for no reason, and brain wrap. That's why I cleaned the washers and shaft thinking if there was a peice of metal or dirt that didn't allow the deck to spin properly.

After having cleaned, greased, and reassembled, we went to start the next show. (Mind you, our tech was just here, and he timed the platter) We set the take-up arm right at the point to where if you just spin the motor, it takes up. Hit the start button, it started to spin, but the take up arm just dropped right out. Could this still be a problem with the filter disk?

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