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Author
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Topic: Fail Safe Failure?
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Steve Scott
Phenomenal Film Handler
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Posts: 1300
From: Minneapolis, MN
Registered: Sep 2000
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posted 08-22-2001 09:48 PM
OK, first show of Rat Race today, I thread up one of our Century SAs normally, SPECO platter takes it up normally, & the XeTron Maxil 12 XPC automation starts & gets thru one trailer fine. But, I come back ten minutes later & the film is shooting onto the floor without even touching the failsafe! I look to the takeup platter & it's motionless. After stopping the system, I try to bring the platter back to life, but it's useless. So I cut the print out of the projector try the bottom platter (it's a 3 deck), it takes up the film that was on the floor, & after a splice where I cut it, it takes up the rest of the print just fine! ![](http://www.film-tech.com/ubb/confused.gif) 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? p.s.: I'm certain it wasn't a power failure.
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Steve Scott
Phenomenal Film Handler
![](http://www.film-tech.com/ubbmembers/630c.jpg)
Posts: 1300
From: Minneapolis, MN
Registered: Sep 2000
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posted 08-23-2001 01:18 AM
Actually, the film was exiting the soundhead & hadn't even reached the fail safe yet. The system is mechanical with the 2 arms w/ rollers (the rollers are magnetic for the automation cues if I'm not mistaken) that ride on the film & if they drop below a 90 degree angle, the system shuts down. 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?
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John Walsh
Film God
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Posts: 2490
From: Connecticut, USA, Earth, Milky Way
Registered: Oct 1999
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posted 08-23-2001 10:23 AM
I've never used the SPECO platters, so I can't really comment on them.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.... ![](http://www.film-tech.com/ubb/smile.gif) 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. Sorry to go on.. hope this helps!
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