Film-Tech Forum ARCHIVE: strong platter control arm moves up and down

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Posted by Michael Voiland (Member # 5386) on 01-30-2010, 03:06 AM:

Has anyone had any issues with the strong platters control arm moving up and down when the film is running and i mean by cycling like it will drop 4 inches speed up and go all the way up and slow down repeating the cycle.

Posted by Monte L Fullmer (Member # 2797) on 01-30-2010, 03:31 AM:

sounds like the drive tire that runs the deck is slipping from either lack of full contact or worn tire rubber (easy to change out), brushes in the motor are definitely worn, or you got a dandy of a bent deck.

If it's the first, raise the motor a smidge so the drive tires are in full contact with the undersurface of the deck.

If you got a bent deck, take the deck off, lay it on the floor face down so the spider braces are facing you, take a pair of visegrips bend and straighten out the braces. This will somewhat get rid of some of the warps.

-Monte

Posted by Tom Wienholt (Member # 1510) on 01-30-2010, 04:51 AM:

Sounds like a problem with the variac.

Posted by Tony Bandiera Jr (Member # 2365) on 01-30-2010, 12:06 PM:

Sounds like yet another theater that needs to get rid of those [bs]

Strong platters... [Big Grin]

Posted by Bernie Anderson Jr (Member # 410) on 01-30-2010, 04:41 PM:

I encountered this problem on Thursday. I'm running Strong AP3 platters with Phase control brains. If the control arm is going up and down and pulsing the platters what is happening is the inner contacts on the variac are probably gone.

You need take the variac out. Unplug the platter first. There are three bolts that hold the whole control assembly box to the platter. Remove them and the allen screw that links to the control arm, unplug all three wires connectors in the control box.

To remove the variac from the control box you need to remove the spindle that controls the variac first. There are two set screws on the wiper assembly, loosen them and remove the spindle (should pull straight out). Now, remove the three wires that go to the terminals and the three screws that hold the variac in. It should come right out after that.

Take the bottom plate off the variac (held on with 4 bolts.)

Now on the bottom, there is a retaining spring clip, remove that and the plastic washer. The whole wiper assembly should come out of the variac. On the inside, you will see 3 little piece of copper. They're probably burnt up, and shortened from arching.

To temporary fix them, bend them down a bit and try to clean them as good as possible. Also clean the inner contact ring which is held down with one screw and collar ring. Clean that, its probably burnt up too. Check your brush too. It should be pointed and not flat.

Clean the winding side of the variac. Its probably all black in the area where the platter likes to normally run. Then put it back together. It should get you through and should only take about 15 mins to do. But try and order that whole assembly and contact ring, if you can. Strong will tell you to replace the whole variac for $500. Dumb, especially if you can rebuild it. I'll try and get a part number for it.

Bernie

Posted by Monte L Fullmer (Member # 2797) on 01-30-2010, 04:57 PM:

I've done variac replacements without removal of the box, but you still have to take out the variac shaft and arm. And to do that, it takes a 1/16" allen wrench (I use a screwdriver allen) to loosen the two allen set screws to remove the shaft and arm from the variac, and these setscrews are located between the rotor and the body of the variac.

Parts for the Staco 1010 variac

2103 Contact ass'y Variac
1005 Brush, Variac

Sad thing, if the contact rotor is pitted due to a worn button, that will also have to be replaced, which entails a new Pt # 1006 Transformer 110v replacement kit.

If you have to replace the variac, the three holes have to be tapped out with a 1/4x20 tap for the mounting screws to work since the new variac will not have holes tapped out for mounting screws-even though the screws themselves are self-tapping, but it's a lot easier to mount the variac in the box with the holes already tapped.

Then, come the instructions on how to set "mechanical zero": after this is all done and installed: You lift the "trombone" all the way to the top, hold it, and have that arm loosened. You turn the shaft all the way counter-clockwise til it stops then turn the shaft about 2* clockwise then lock down that arm on the shaft. Then you can lowe the "trombone"

Should be set to go.

Course, if you have an extra MUT, you can snag the variac out of that one for the problem platter

-Monte