Film-Tech Forum ARCHIVE: Platter continuously reverse wraps

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Posted by Manny Montes (Member # 5639) on 03-24-2010, 02:55 AM:

As all booths do, I have one platter that loves messing with me, the top platter will occasionally (once every 2 weeks) backwrap as the control arm in the brain gets stuck forward and keeps the platter turning until it back wraps. We've tried replacing the microswitch because we thought it was getting stuck, but that was no good.

Now i'm sitting with a useless top platter and wondering what to do.

Posted by Monte L Fullmer (Member # 2797) on 03-24-2010, 03:23 AM:

Are your decks level? get a bubble level and put it across and in line with the tower, for an off-level deck will cause the arm to not work correctly. Also, is the microswitch breaking connection when the arm is dead inbetween those two outer diameter rollers? For if it's opening late, this can also cause backwrap.

And you adjust the whole microswitch and don't bend the tang, plus the spring under the tang has to be gone.

What about other brains mounted in this one deck? Do they act up the same way? Or, is your units solid mount brains?

I've shimmed, or adjusted the feet of many platter decks up to level.

-Monte

Posted by Manny Montes (Member # 5639) on 03-24-2010, 03:39 AM:

I will check how level the decks are when I go in tomorrow, I do know that they are all warped. Old theater and A certain company before mine didn't focus on presentation or projection training. The system has solid mount brains.

I'm pretty positive it has nothing to do with the microswitch, however the problem seems to never occur when I am working, and it can't be narrowed down to one person either. For now we aren't using the platter and even when we were I couldn't replicate the issue whenever I threaded it, so it's being very difficult indeed.

Posted by Louis Bornwasser (Member # 3063) on 03-24-2010, 04:14 AM:

Top platter?? Probably misthreaded by short person.

The giveaway is that it is always the top platter AND it does not happen to you. Louis

Posted by Manny Montes (Member # 5639) on 03-24-2010, 04:32 AM:

haha, unfortunately it happened with 2 others that are taller than I am.

Plus, I can't just kick short people out of booth can I?

Posted by Joe Redifer (Member # 3) on 03-24-2010, 05:27 AM:

You didn't even mention what kind of equipment you are working with. That would go a long way towards a solution.

Posted by John Wilson (Member # 269) on 03-24-2010, 05:58 AM:

Ageed.

A long way...

quote: Manny Montes
Plus, I can't just kick short people out of booth can I?

No, they'll kick you in the ankles.

Posted by Ian Parfrey (Member # 5122) on 03-24-2010, 06:29 AM:

... or bite your toes off. [eyes]

Posted by Michael Voiland (Member # 5386) on 03-24-2010, 09:51 AM:

I am guessing Strong / Potts platters with a fixed brain.... We have a few of those that like to cause trouble.

Posted by Jim Cassedy (Member # 4115) on 03-24-2010, 12:28 PM:

quote: Louis Bornwasser
Top platter?? Probably misthreaded by short person.

Oh really? I had the same problem on a bottom platter deck
caused by tall people threading who were too lazy to bend
all the way over to check their work. [Wink]

But seriously- - check the platter deck level as others
have suggested. Especially if it's a STRONG platter.
They seem to be pretty picky about any degree of tilt.

I had the same problem till I found mine was off level.

Curiously, I have at least one which works better when
it's NOT level. I've never figured out why and I don't
intend to. I have an "If it works, don't muck with it"
attitude about this one. It works great when the back
(column) end is slightly elevated in relation to the
other two legs. But if I "level" it, like the others,
it gives me all kinds of problems. Go figure. . . .

Posted by Richard Hamilton (Member # 321) on 03-24-2010, 12:35 PM:

Have you actually witnessed the control arm sticking and causing the wrap, or do you just happen to catch it after its wrapped enough times it wont move?

Posted by Manny Montes (Member # 5639) on 03-24-2010, 12:46 PM:

I've never caught it myself even, others just told me that its wrapping and its because the arm is sticking. Its only a 5 plex so we never have a "dedicated projectionist" to stay in booth all day (shame really), they would catch it after the failsafe has cut the show.

Posted by Tony Bandiera Jr (Member # 2365) on 03-24-2010, 01:13 PM:

Simple solution: Replace that Strong piece of [bs]

with a Christie AW3R. [Smile]

Good used ones can be had for around $500

Posted by John T. Hendrickson, Jr (Member # 849) on 03-24-2010, 01:14 PM:

If it is an old Potts, you may want to check the bearings in the post of the arm. If they are bad, they will prevent the smooth movement of the arm. They may need to be replaced. I have had occasion to do this.

Posted by Manny Montes (Member # 5639) on 03-24-2010, 01:28 PM:

Trust me, I wish I could replace a lot of things in our booth, however I'm constrained by a megacorporation. We've had a blown amp for 2-3 months now, still no replacement...

I'll check that the bearings are ok, considering the age of the platter that might be it as well

Posted by Chris Slycord (Member # 4239) on 03-24-2010, 01:54 PM:

Also check that the area underneath the speed control arm is nice and flat. I remember having one strong brain where the control arm would get stuck because the metal underneath it had a raised spot. It started to wrap, then got enough tension to pull the arm past the raised spot and get rid of the wrap. And it did it throughout the show and was definitely easy to fix.

Then again, the incident isn't reproducing when you thread, so it's likely not that.

Posted by Richard Hamilton (Member # 321) on 03-24-2010, 02:18 PM:

WHAT MAKE AND MODEL OF PLATTER? At least give us a hint...what color is it?

Posted by John Wilson (Member # 269) on 03-24-2010, 03:18 PM:

No, it's more fun to guess. [Roll Eyes]

Posted by Monte L Fullmer (Member # 2797) on 03-24-2010, 04:11 PM:

Interesting of that "the others" mentioning of this problem and not "Mr. Manny" here ...

..are stories being told...?

But, what I can see, if they have the old brains, that center roller is NOT held down by a screw or an "E" clip as does the later models. Thus, that roller has an easy chance of riding up on the shaft and wedging itself under this arm....and THAT, I've seen many times, esp with booth personnel setting aside brains that are presumably dead, but that roller has just simply wedged itself under the arm.

..and no effort in trying to take any sort of inititave of remedying any problem....which it looks like the case here.

-Monte

Posted by Sean McKinnon (Member # 612) on 03-24-2010, 04:33 PM:

quote: Manny Montes
We've had a blown amp for 2-3 months now, still no replacement

There really is no excuse for that... FYI guitar center repairs amps.

Posted by Michael Voiland (Member # 5386) on 03-24-2010, 04:43 PM:

I would rather jump off the roof then go to guitar center [Wink]

.

If its a QSC have it sent to the factory. At least you can get by on a blown amp. 5 of our 9 theaters only have one amp. Center surround is bad. All strong platters. WD40 works wonders if you can take apart the brain clean all the crap out of the bearings with compressed / canned air and wd40 then take a towel and rub the over spray off.

Works ok on our platters i am not sure if it will work for you.

Posted by Sean McKinnon (Member # 612) on 03-24-2010, 04:55 PM:

When I was a tech in Boston we used to send them to Manchester NH to get repaired by a chain called "Daddy's Junky Music" I am not sure if they are just a New England chain or not but they did pretty decent work at a reasonable price. They were fast too.

Posted by Manny Montes (Member # 5639) on 03-24-2010, 05:18 PM:

Sorry about the late response, at work right now. The platter and everything is level, there is no raised spots underneath the control arm. I checked the control arm and it continually swings smoothly and clicks the microswitch at just the right position.

It is an old Balco platter (3 platter).

Posted by Monte L Fullmer (Member # 2797) on 03-24-2010, 05:53 PM:

OKEY ! That explains the whole problem.

BALCO's are the predecessor to the present STRONG ALPHA platters and made in the early 80's. They have same design (nifty use of a switch on the motor for the controls of rewind and makeup with the actual manual control of unplugging the motor from the arm and connecting it to the MUT to do the builds...), same vacuum motors to drive the platters, et.al, but uses a cable from the variac to the trombone instead of the rod.

BUT, their brains are totally much to be desired: The same design as the present STRONG brain,but they use, what's called a snap action roller switch which has a much shorter arm with a roller on it that rides against the pin on the control arm.

The lever action is much coarser than the present easier tang snap switch and it's very easy for backwrapping to occur.

What I've done is to disassemble the control plate from the platter arm and redrill the plate to accept the more common snap action microswitch kit since it's mounted in a different position on the plate.

After this mod, the backwrap issues totally disappeared with these BALCOS..

-Monte

Posted by John Wilson (Member # 269) on 03-24-2010, 06:01 PM:

quote: Manny Montes
It is an old Balco platter (3 platter).

There...that didn't hurt.

quote: Monte L Fullmer
BALCO's are the predecessor to the present STRONG ALPHA platters

There's your problem right there. [puke]

Posted by Manny Montes (Member # 5639) on 03-24-2010, 06:41 PM:

Alright Monte, I will have to try that mod.

and yeah, sorry about not naming the brand and stuff, I've got 5 projectors with 4 different platter systems and I couldn't remember off the top of my head which was #3.

Posted by Louis Bornwasser (Member # 3063) on 03-24-2010, 10:40 PM:

Boy! Whomever is responsible for causing that train wreck should be whipped with a wet noodle! Never have dissimilar units in the same building unless they are close.

btw: the Strong/Potts platters are just fine, easy to fix, and cheap to buy/repair. The older unit can be easily converted to a nearly new model (or you can do-it-yourself like Monte describes. . . . buy one new "brain" and then you will know what to do.) Louis

Posted by Manny Montes (Member # 5639) on 03-24-2010, 11:27 PM:

Yeah, it was a single, the expanded to a twin and is now 5 theaters. So there is a lot of dissimilar equipment. Each projector is threaded a different way as well, due to space constraints and platter position. One projector is threaded through its base.

Posted by Michael Voiland (Member # 5386) on 03-25-2010, 01:51 AM:

Don't worry lots of people are in that boat. Due to cheapness or expansion or both. We currently have pro 35s a single turreted simplex and 4 simplex 35's 2 versions of the strong platters 4 types of lamp house and 5 different sound system setups with 2 types of processors. It adds up to a heck of a lot of training.
Good luck with the brains on your platters.

Posted by Joe Redifer (Member # 3) on 03-25-2010, 02:14 AM:

It must be hell training someone in that booth. I get frustrated in mine because we have Simplex XLs as well as Milleniums, and the top loop size must be smaller on the Milleniums. Not only that, but we have BACP Dolby Digital penthouse readers as well as Dolby Cat 702 readers and the BACP requires more tension than the Dolby proper readers. I won't even get into the automation differences. It's a pain.

Posted by Sean McKinnon (Member # 612) on 03-25-2010, 12:18 PM:

I worked one theatre in North Attelboro, Mass that had ten screens and a different projector/platter/lamp house/power supply/sound processor/automation in every house! Actually Rachel Gilardi and Paul (I forget his last name but hes from rhode island) were managers at this location.

The platters were funny because they had everything from a phillips roto-matic to potts, to a brand new Kinoton! Crazy.

This dump is now closed thankfully.