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Topic: Timing Cinemeccanica Platters/Feed Units

Frank Aston
Film Handler

Posts: 54
From: Albrighton, Shropshire, UK
Registered: May 2000

posted 09-07-2002 11:56 AM

Could I prevail upon the collective 'brains' of this wonderful forum for a consensus on the most simple method of platter timing?

My experience has included use of coins, film loops and complex arrangements with multi-meters as well as counting the rotations of a platter within a given time.

News of recent experimentation or the latest thinking would be welcome.

"It's always better on the BIG SCREEN".

Kind regards,

Frank.

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William Hooper
Phenomenal Film Handler

Posts: 1879
From: Mobile, AL USA
Registered: Jun 99

posted 09-09-2002 12:09 AM

What kind of platters?

For Potts platters: Red 20 oz. Coke tops stuck upside down with a loop of sticky tape on top of the platters. Excellent emergency platter pucks, too. Wipe any adhesive residue away with a bit of alcohol afterwards.

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Daryl C. W. O'Shea
Film God

Posts: 3977
From: Midland Ontario Canada (where Panavision & IMAX lenses come from)
Registered: Jun 2002

posted 09-09-2002 12:23 AM

I believe Frank is interested in timing a Cinemeccanica Platter.

As for marking the platter decks for counting revolutions, a piece of black electrical tape a few inches long works just fine (and you won't have concessionists bitching about their inventory counts).

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System Notices
Forum Watchdog / Soup Nazi

Posts: 215

Registered: Apr 2004

posted 09-11-2004 08:14 AM

It has been 733 days since the last post.

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Tommie Evans
Expert Film Handler

Posts: 116
From: Birmingham, West Midlands, UK
Registered: Sep 2004

posted 09-11-2004 08:14 AM

Timing Cinemeccanica platters <CNR3-35N> here goes....

Speed adjustment of the Pay-out (feed unit)

1: Remove the back cover of the platter tower to gain access to the speed cards.

2: Insert the payout unit into the top platter, move the pay-out control arm to 5-degrees (use a two pence coin placed on top of a ten pence coin) and notice its speed. It is recommended that the platter should just move very slightly.

3: To obtain this setting, loosen the allen screw that locks the speed control arm to the potentiometer spindle, and with the arm still at the 5-degree angle rotate the pot spindle with a small screwdriver or dolby pen until you get the desired setting.

4: Now move the arm to it's 100% or full position, use masking tape to hold it there. The platter should rotate once a second

<tip> To time the platter place several strips of masking tape to the rim of the platter, as the platter spins you can 'hear' the masking tape pass over the motor drive wheel. Use your watch to time the platter. Adjust the trimmer on the card until the desired setting is achieved.

5: Now re-check the speed at the 5-degree setting, adjust the pay-out pot if needed to achieve slight movement.

<for the remaining two platters you do not need to touch the pay-out pot, as it is now set for all three platters>

6: Now place the pay-out unit into the second platter at 100%, adjust the second trimmer to achieve the desired speed.

7: Now do the same for the third and final platter.

NB: the platter system needs to be perfectly level, check it left-to-right / back-to-front with a spirit level.
If the platter is slanted it will throw the print without fail.

Take-up adjustment.

1: Make a loop of film out of 130cm. Place the loop of film on the return arm and the selector rollers of the top platter.

Notice the spped <it should be moving slightly>

2: To adjust the take-up speed remove the platter axel cover and loosen the two small grub screws hold the aluminium block to the pot spindle.

3: Use the potentiometer spindle collar <microswitch actuation collar> to set the trim of the pot to 'slightly moving'

4: retighten the grub screws once you obtain the correct setting.

5: loosen the collar screw <microswitch actuation collar and move it into position so that it presses the failsafe mircoswitch as the very end of the run off the return arm.

<end>

NB: if the collar screw shears off <set to tight at the factory> you will need to rebuild the axel:

start by removing the return arm, spring, connections and axel support completely from the support tower.
Drill or remove the collar and broken screw and remove the variable resistor and replace

Design flaws:

As the film ends and the return arm snaps back it will damage the rubber strip, reverse or replace the rubber strip.
As the film ends and the return arm snaps back it will work the fragile legs of the resistors on the terminal block loose, remove the screw holding the block to the axel support as it will soften the return arm 'spring back' on the resistors.

The brass collar that the variable resistor (50k pot) screws into is crap - if you have to rebuild replace it will a similar component from RS as you get a small nut rather than a weak brass collar. And as for the collar screw never over tighten.

[Wink]

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Antonio Marcheselli
Phenomenal Film Handler

Posts: 1260
From: Florence, Italy
Registered: Mar 2000

posted 09-18-2004 05:15 AM

Tommie

There's something I cannot understand in your method.
If you set the maximum speed using the payout arm in its full speed position, and you change the trimpot located in the chassis on the rear, you'll also change the 5° speed, or not?

What I noted is the following: you can make the platter works with both the speed card's trimpot at maximum or at minimum, then you just have to compensate with the payout resistor.
BUT, the behaviour of the platter IS NOT the same. If the speed card's resistor is set almost to maximum, then the platter will have a smooth movements. It will not accelerate too fast.
If you setup the platter setting the speed card's resistor at minimum, then the platter will accelerate too fast.

I think that a correct method should include a meter and start to a given value of the back resistors.

With my meter I found that the platter starts accelerating too fast when the voltage at the motors goes behind 200V.

However, one revolution per second would be optimal for me but I never achieved it.

Give me your opinion. I'll check your method immediately today!!!

Bye
A

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Tommie Evans
Expert Film Handler

Posts: 116
From: Birmingham, West Midlands, UK
Registered: Sep 2004

posted 09-18-2004 07:18 AM

Antonio

This method was shown to me by an engineer, I usually time the platter by going through the instruction manual step-by-step.

In the manual there is a diagram of the speed cards trim pot, so I set the pot around this setting to begin with.

I try and get a balance between the high and low setting but have not tried your method. I will try out your method shortly although our platters have a smooth acceleration as well.

We only re-time the platter system if there is a problem or if film start flying off like frisbees [Big Grin]

regards

Tommie

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Antonio Marcheselli
Phenomenal Film Handler

Posts: 1260
From: Florence, Italy
Registered: Mar 2000

posted 09-18-2004 07:37 AM

Tommie

Yes, I forgot that there is a picture in the manual of the trimmer.

I wonder why ALL of my CNR has a different factory settings. Once I had trouble with one platter, so I check others platters with meter to found a method. None. Each platter is factory adjusted with absolutely no method. Every trimmer on the cards were adjusted to a different value.

However the picture in the manual shows the trimmer almost in the same position I found out!

There is a trimmer in the payout brain too (inside the black cylinder). Why that trimmers are not set to the same value? What is the purpose of that trimmer? It is connected in series, does it mean that it should compensate for something?
I had once a brain that does not had a "zero" position, I corrected it moving that internal trimmer.

I really would found a TECHNICAL way where there are no photos of trimmer but VALUES!

Like: put all trimmers to 100 Ohm, then adjust the brains until the tension at the motors is 15V... and so on.

About my "discover": I've not too much knowledge in electronics, but are that resistance exponential ones? In that case my method would only put the system to have the brain resistance to work on its more linear zone... I don't know if it it clear...

Bye
A

(edit: I just re-read the CNR manual and I found that the method I have is the official one of Cinemeccanica... [Smile]

)

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Antonio Marcheselli
Phenomenal Film Handler

Posts: 1260
From: Florence, Italy
Registered: Mar 2000

posted 09-19-2004 09:47 AM

Tommie

I made some tests, I found that what is wrote on Cinemeccanica's manual (check the minimum, then adjust the maximum and then adjust again the minimum) is impossibile! If I set the minimum from center's pot, and then I adjust the maximum from card's pot, the minimum will MUST change!!!

I found on the same platter that I have two center operating in a different way. If I set one to 60 revolution for second, I obtain the correct minimum (5°=STOP). With the other one if I set 60 revolution for seconds, I have the STOP of the platter far from the correct point. But I CANNOT adjust it without changing the maximum too!!

Inside the center there are a contactless rotary sensor at 15.000 Ohm, and a fixed potentiometer at 20.000Ohm. I checked few center and I found that that fixed potentiometer has not a common setup.

Probably to have the center operating correctly I have to adjust that potentiometer. What do you think?

Ah, now the first center (the one that is set up properly) is working perfectly.

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Tommie Evans
Expert Film Handler

Posts: 116
From: Birmingham, West Midlands, UK
Registered: Sep 2004

posted 09-19-2004 10:58 AM

At 5 degrees minium we set the platter so it is rotating about 1.5 per minute and at the maximun we set the platter so it is running at 1 rotation a second.

It is the maximun setting we get problems with as if it is anything over 1 rotation a second the film gets thrown off.

When we set the feed unit on the top platter for it's minium setting (trimmer inside the feed unit), we leave this setting for all three platters.

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Antonio Marcheselli
Phenomenal Film Handler

Posts: 1260
From: Florence, Italy
Registered: Mar 2000

posted 09-19-2004 02:29 PM

Tommie

How can you control SEPARATELY both maximum and minimum???

Bye
A

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Tommie Evans
Expert Film Handler

Posts: 116
From: Birmingham, West Midlands, UK
Registered: Sep 2004

posted 09-20-2004 09:18 AM

Hi antonio

I'm not sure on that one, I guess if you look at the Christie platter you'll see it has a high and a low setting - one for sensitive adjustments at the lower end of the operating speed and one for high speed adjustments.
I'm not to sure how this works as I'm not knowledgable about electronics. Maybe someone on this forum can explain!

Tom.....

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Antonio Marcheselli
Phenomenal Film Handler

Posts: 1260
From: Florence, Italy
Registered: Mar 2000

posted 09-20-2004 10:24 AM

Are you saying that you never had the problem I explaining? Cinemeccanica has not other trimmer that ones we talked. And I never saw a Christie!

Bye
A

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Antonio Marcheselli
Phenomenal Film Handler

Posts: 1260
From: Florence, Italy
Registered: Mar 2000

posted 10-20-2004 02:42 PM

I'm showing my last results so that someone can complete them or can help me.

let's say that the timing issues for CNR platter are three:

1. Have the correct minimum: 5°=stop
2. Have correct Maximum: at maximum the platter should make 60 revolution for seconds. This is very important for correct operation, more important than minimum.
3. Have both payout unit working THE SAME, both at minimum and at Maximum.

I discovered, with the help of one of you, that the trimmer on the control card adjust the "dead" zone of the trimmer of the payout unit.
More the "dead" zone (trimmer on the card clockwise), more the maximum speed, when minimum is set.
Less the "dead" zone (trimmer on the card counterclockwise) and less the maximum speed, when minimum is set.

So I took a payout unit and I set it so that when the minimum is set the platter rotate 60 times per minute (about 180V).

Since often if I take the other payout unit and I set its minimum, its maximum is not correct (with the same control card's setting of the other payout unit), I discovered that the only way to have the payout units work the same is to access the trimmer INSIDE the payout unit and adjust it until the payout units have the same behaviours. This internal trimmer seems to have the same function of the card's trimmer, to raise or lower the "dead" zone, and the maximum speed with it.

But, there is a problem.

When the "dead" zone is reduced (condition for having a reduced speed at maximum), the payout unit is VERY sensible to temperature. So it is not uncommon that the minimum can vary greatly within the day or that the payout unit does nto have a stop position anymore.
But if I raise the "dead" zone I have a minimum more stable but too much maximum speed (up to 230V...).

I'm testing a platter since three weeks, I'm not reach a final solution.

Has anyone have a solution or an idea???
Bye
A

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Tommie Evans
Expert Film Handler

Posts: 116
From: Birmingham, West Midlands, UK
Registered: Sep 2004

posted 10-20-2004 04:47 PM

quote: Antonio Marcheselli
So I took a payout unit and I set it so that when the minimum* is set the platter rotate 60 times per minute (about 180V).

If you set the minimun for the pay-out and then trimmed the maximum (60 times per minutes) does your miniumun setting then change?

If the temperature of the pay-out increases then I guess the resistance would drop allowing more current through the circuit?

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