Now what I'd like to know is not only why the takeup platter wasn't working (I verified that all the right buttons were pressed), but why the fail safe didn't shut down the system when the film started flying to the floor!

This projector hasn't given any of the operators in our booth any trouble since we had it last serviced, and the platter has always worked fine (In fact, the next four shows ran fine on the same platter!). Was this a failure in the platter or the automation?
Has anybody seen anything like this, or does anybody know which component is the culprit?

On the mechanical kind, the microswitches can get clogged, dirty. Usually they are replaced.

This feature actually works too well. I have to hold the film up until it gets up to speed, or else the system won't start up.

I did have a suspicion that the system needed cleaning. Our last booth manager almost never maintained the platters until they broke down. I'll definitely clean the automation switches, check the wiring, & I'll make sure that we get the platters cleaned.

Our GM thought that the film could have jumped or got woulnd too tight around a roller on the fail safe. Any thoughts on this theory?

Even though you use the Xetron Maxi 12 XPC automation, that does not define the type of failsafes you are using. It is *very* common to mix and match components. For example, regardless of the kind of automation, Xetron can supply three types of failsafes; all electronic failsafe/cue detector; a mechanical failsafe with electronic cue detector; or all mechanical failsafe/cue detector.

Sometimes Xetron's cue detectors use a short lenght of foil on the film edge; sometimes it's a reflective rectangular stick-on that's goes in the center of the film. No failsafe/cue detector I've ever seen used anything magnetic, because of the damage it would do to magnetically-striped prints. I don't think the film jumped or wound too tight on any rollers... you would have seen that when you discovered the problem.

Getting into more detail than you may want to know....

Mechanical failsafes use a microswitch; when the film breaks or ends, the two arms drop and press on a lever on the microswitch. Check that the two levers swing freely; sometimes people tighten the allen screws that hold them too tightly, and they bind up. The microswitch is a special type, defined in the catalog as an "easy-press" because it takes very litte pressure to activate it. Many techs incorrectly replace it while servicing with the standard type, which is harder to activate (the levers are not heavy enough to throw the switch when they drop.) It is almost enough, though, and may work most times, which is why it can look like an "only once in a while" problem.

(Film has been known to tear, yet continue to run, while splitting down the center for the whole length of a feature. One side goes on the floor; the other back to the platter. That's why there are two levers- to catch this problem.)

I don't know if this is your problem, but the switch is cheap to replace: http://www.simtechswitches.com/micro.html http://www.mouser.com/catalog/cat_606/349.pdf

If you wish to see the specs for this switch: http://content.honeywell.com:80/sensing/prodinfo/basicswitches/catalog/12.pdf

The switch part number is : V3L-2106-D8
Other manufacturers make equilvents to this switch, but the Honeywell/Microswitch is the most widely supplied.

The automation itself may have a problem. When using mechanical failsafes with reel-to-reel, the film will often develop slack at start-up. To prevent shutting down the show, the automation will ignore the failsafe switch for about 5 seconds after start, then become active, to allow the reel to catch up. When running with platters, you don't need that feature, but it's still in the automation and there may be a problem with it. The Xetron Maxi 12 XPC automation does not use cam timers- it is all electronic (except for relays.) You should leave this to a tech who is familiar, (unless you are good at electronics) 'cause it's complicated in there!

Look in the "Manuals" download page, under, "Generic foil cue detector/failsafe UDH-1-100" and see if it looks like yours.

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There are a couple of microswitches that remove power to the takeup platter if they are activated. (When the yo-yo is all the way at the bottom.)
If these switches get jammed or just plain get old and quit working it would cause the problem you describe, but not usually in the MIDDLE of a show.

The second place I would look would be in the pushbutton switches under the control box. Sometimes they get sticky or the contacts get fried and pitted.
(Minimize burned contacts in the switches by never changing switch settings when any deck is under power.)

Gord:
The tension theory seems right, seeing as how these SPECO platters only give us problems when either the fuse blows in the tree, or the tension in the rollers jams or releases the film.
The film could have jumped the last roller on the fail safe & increased the tension while still holding the yo-yo up.