Film-Tech Forum ARCHIVE: Dead (?) Strong AP-3

This is topic Dead (?) Strong AP-3 in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Rick Long (Member # 213) on 05-09-2002, 11:34 PM:

I received a call from one of our theatres this afternoon, from a manageress/projectionist whom I have known for a few years now. She knows her equipment quite well and knows which end of a screwdriver is the handle. Unfortunately, the theatre is about a 2-hour drive away.

She reported that the platter (Strong AP, with Simplex console and TA-10 automation), was dead, as she went to thread it up, this afternoon. The lights on the platter, however were on. All three decks were dead even though the appropriate take-up rollers were lifted and the elevator raised.

Thinking back to a similar problem I had about a month ago (in another theatre), I advised her to hard-wire by-pass the wrap detector in case another micro-switch had failed. She did so, but still the platter still was dead.

I knew her abilities well enough that she would not overlook anything obvious before calling me, so I attended to the call.

When I got there, of course, the damn thing worked just fine (like this hasn't happened to every technician who ever lived).

I examined the variac (brushes and stator contact were good)( I sprayed the variac with contact cleaner nonetheless), line cords were fine, no micro-switches either on the wrap detector or lower elevator limit-switch were sticky) - in short, the damn thing worked ! -even after i kicked the living bejesus out of it to try and make it fail.

It was in talking to the "new projectionist" who had been on duty the night before, that the story began to unravel a little more.

He reported (this was about an hour after I was already beating up this platter with karate kicks) that during the credits on the 7:00 show, the alarm on the TA-10 beeped, and the projector shut down. He cleared the projector with the hand wheel and threaded the next show. It was at this point that they found the platter to be dead, and promptly cancelled the last show.

OK, understanding that if the platter failed during the end of the 7:00 show, and the TA-10 had not seen "film-motion" it would have signaled a fault, explaining the shut-down.

So why did the platter fail in the first place?

P.S. as far as I know, it worked fine tonight.

Posted by Ken Layton (Member # 133) on 05-10-2002, 12:34 AM:

Check the wrap detector microswitch with a good ohm meter. Also check the elevator microswitch in the variac box with a meter. Check all the connectors in the variac box for any pins that may have gotten pushed back or not fully seated in the connector housing.

Posted by Paul G. Thompson (Member # 655) on 05-10-2002, 12:47 AM:

Better yet, replace the micro-switch in the wrap detector. Micro-switches can check OK with an ohmmeter, but when they are placed in a dynamic situation, they can become flakey very fast, especially if they are old. Seen it happen, and got caught with my pants down several times.

Posted by Rick Long (Member # 213) on 05-10-2002, 01:14 AM:

Yeah, the wrap detector was my first suspect too, but the fact that she by-passed it (advised to put both terminal lugs under the same screw, which she did) and the fact that the platter was still dead, leads me to beleive that the fault may be elsewhere. Still, on my next trip down there (hopefully in a week or so, I am going to replace it anyways. Although I did check the variac box connections i will DOUBLE-CHECK the next time, anyways.

Posted by Pat Moore (Member # 380) on 05-10-2002, 11:04 AM:

Hi -- I'd be a bit suspicious of the molex plug and connector that the Wrap Detector gets into the system with. It's easy to check, right under the cap of the post.

How old is the platter?

Pat

Posted by Bill Hallsworth (Member # 1240) on 05-10-2002, 01:08 PM:

Did you check the fuse for the variac? Some of the Strong platters have seperate fuses for the variac and the lights.

Posted by Rick Long (Member # 213) on 05-11-2002, 12:31 PM:

No problems here since my last post.

Thank you Pat and Bill. This platter is about six years old. I will check the molex connector on my next call to that area.

I have, however, started harboring a suspicion that perhaps, on that night, the failure could have been caused by a sticking wrap detector (due to the manual over-ride screw being too far inward), and that perhaps in desperate efforts to get the show going again, the "newbie" operators in the booth tried pulling the two fuses in the variac box.

And then replacing them in the wrong order.

This would result in the 8-amp fuse being put in the light circuit, and the 2-amp fuse being put in the motor-drive circuit. This would result in no motor drive when the 2-amp fuse blew.

After putting in the emergency call, they MAY have discovered their mistake and changed the 2-amp fuse and replaced both fuses into their proper sockets, then, of course, shrugged when I could find nothing wrong.

This would bother me more than the problem however, as most of the staff at most of our theatres know that I am NOT the type who goes running to supervisors with tales of staff goofs. The staff at this theatre (save the manageress) is relatively new, however, and may not have known that.

Posted by Pat Moore (Member # 380) on 05-11-2002, 05:14 PM:

Rick, looks like one of those things we may never know what happened. All the fundamentals are covered though and your crew, all things considered, sounds like they try and work pretty well at it. Lotta people don't even know what a fuse is, it seems, so it sounds like you did a good job of traing people. Bet the show's good when it's on screen.

Pat