Film-Tech Forum ARCHIVE: Upper Feed Sproket Running Fast on Victoria 5

This is topic Upper Feed Sproket Running Fast on Victoria 5 in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Daryl C. W. O'Shea (Member # 1303) on 08-06-2002, 07:44 PM:

Hi,

Would anyone know what would cause the upper feed sprocket on a Cinemeccanica Victoria 5 to run faster than the intermittent and the lower holdback sprocket, causing the loop before the gate to become larger and larger (sometimes an extra frame a second)?

Belts seemed to be alright, a little worn though. Replaced them and still have the same problem. Readjusted tension, no difference.

This happens immediately on startup and at full motor speed.

Old style gate.
Projector is fitted with a Cat 701 reader.
Strong A3 Platter.

Thanks,

Daryl

Posted by Richard Fowler (Member # 893) on 08-06-2002, 09:08 PM:

The inner drive belt runs both the upper and lower drive sprocket in addition to the shutter box and intermittent and assuming with an 1/2 ( 12 - 13mm ) play on the timing belt, from the top idler to lower sprocket pully, they should stay in sync. Check to see if the intermittent locking washer & nut is not loose or broken, the upper sprocket mounting screw is tight, and the upper drive sprocket inner and outer timing gears are properly seated on the woodruff keys on the drive shaft with no side play.
Russell Fowler
TVP-Theatre & Video Products Inc. www.tvpmiami.com

Posted by Rick Sanjurjo (Member # 1365) on 08-06-2002, 09:08 PM:

Daryl,

I haven't worked an a V5 in a long time, but I would start by looking at the belts and making sure that the belt between the upper sprocket and the rest of the machine isn't missing any teeth or that it isn't loose. Next I would check the inside pulley on the upper sprocket ( that drives the rest of the machine if I remmeber correctly ) to make sure it isn't missing any teeth or that it isn't loose on the shaft. If that look good then I would try turning the motor by hand and putting a small amount of tension on the inside belt to see if you find a place where is slips. If all that fails then I would ask, has anybody installed a new pully on the projector lately? If so then they installed the incorrect one.

Hope this is of some help
Rick

Posted by Rick Sanjurjo (Member # 1365) on 08-06-2002, 09:10 PM:

Daryl,

If the intermittent pulley is loose not only will the top loop get bigger but the bottom loop should also get smaller.

Rick

Posted by Rick Long (Member # 213) on 08-06-2002, 09:12 PM:

This is weird!

As you know, the upper feed sprocket shaft is driven directly from the motor belt, therefore we have to assume it is running at the correct speed.

Is it therefore, possible that the rest of the projector is running at slightly slower speed? Have you checked the inner belt idler (upper left corner) for correct tension?

Didn't lose any shaft keys while changing belts didya?

Posted by Gordon McLeod (Member # 33) on 08-06-2002, 09:13 PM:

Belt jumping is the usuall culprit check the tensioning idler

Posted by Daryl C. W. O'Shea (Member # 1303) on 08-06-2002, 11:57 PM:

Thanks guys, it turned out to be a big deposite of worn rubber in about 15 teeth on the inner gear of the upper feed sprocket. I assume that it was enough to cause a little slipage, therefore slowing the intermittent and lower holdback sprocket. I guess I missed it with the manager standing there going "fixed yet... fixed yet... fixed yet...".

Of course it would have been fixed before the show started if the guy that had opened told me what he told me on the phone when I called him later, "yeah the top loop got real big for some reason two shows in a row, didn't think it was worth mentioning".