Film-Tech Forum ARCHIVE: Century JJ slow startup

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Posted by Michael Schaffer (Member # 1204) on 02-09-2007, 03:23 AM:

I have a combo 35/70mm machine here whose motor recently exhaled its life when the intermittent seized up. After receiving the rebuilt intermittent and replacement motor (the original was an old GE one), a Ballantyne model # A4R17FB2B - really made by Bodine, of course -, I installed both and everything runs fine except the motor starts up really slow. A slower rampup is of course welcome, but this motor does take its time. Once it's started up, it runs fine.
I did check that everything is mechanically free-spinning, that all the gears are in good condition and lubed, that the intermittent gear is not to tightly meshing with the gear on the vertical shaft, but the same slow startup also occurs when I disengage the intermittent. The motor is positioned so that the belt is reasonably tight with about 1/4" play, and the belts are in good condition with no bad teeth or slippage.
Could it be that pulling the whole mechanism including the 70mm soundhead on top is a little too much work for this type of motor? It has the correct rpms (1800, same as the old one) and I am using the old pulley and flywheel.

Posted by Adam Martin (Member # 641) on 02-09-2007, 04:03 AM:

Are the two motors rated the same horsepower? Does the new motor start slow without anything engaged to it?

Posted by Monte L Fullmer (Member # 2797) on 02-09-2007, 04:27 AM:

Check into a Leeson sync motor. These motors have a stronger ramp-up speed than does Bodine.

I have both on my 5-Star units, and the Leeson ramps up much stronger and quicker to speed than the Bodines.

(must have larger windings in the Leeson that the Bodine has..)

-Monte

Posted by John Walsh (Member # 168) on 02-09-2007, 07:05 AM:

The JJ's I worked with had the 'slow start' resistors added. If yours does also, is it possible they won't work with the new motors?

Posted by Steve Guttag (Member # 268) on 02-09-2007, 08:27 AM:

If you are going from a GE Async motor to a Leeson or Bodine sync motor you also have speed problems. Like others have said there was often a resistor on the start winding of the Async motor located in a black box mounted over the motor electrical cover of the Async motor.

There is also the possibility you have the wrong voltage (motor set to 230 instead of 120).

These are the first things that come to mind.

Posted by Michael Schaffer (Member # 1204) on 02-09-2007, 04:37 PM:

The motor only says "115V" on the type plate, it doesn't give 230V as alternative, but the wiring diagram gives two options for low and high voltage, and I wired it for "high". Could that be the mistake? Some motors list various operating voltages, then the choice is clearer.
There is a box mounted below the motor support bracket, but I thought this was for interlock. The motor wiring coming from the concole goes into that and from there to the motor itself. Might it be necessary to bypass that? There will be no more interlock in this location anyway because they mostly play digital now, and the digital projectors are in the way anyway, so some massive measures would have to be taken to reroute the interlock paths. But, like I said, that isn't likely to be needed in the future anymore anyway.

Posted by Steve Guttag (Member # 268) on 02-09-2007, 05:50 PM:

Open the box...if there is a resistor in it then that is an issue...though it should have only been on the start winding and you should have had 3 or 4 wires to contend with coming out of that box...if only 2 then any resistor would have always be in series and would have gotten very hot.

If the motor is one of those blue jobs with the integral jbox and says Ballantyne then yes...LOW = 115VAC and HIGH = 230 VAC. The Leeson name should be at the very bottom of the name plate. Also in the "Volt" box on the name plate it might say 115 but look at the box to the right of that (unlabeled) it will most likely say 230.

I'm betting this is your problem.

Steve

Posted by Mark Gulbrandsen (Member # 72) on 02-11-2007, 04:23 PM:

Michael,

A Baldor three phase 1/4 horse with a single phase solid state drive would be the better way to go and they are about the same price. Aside from varialbe run up/run down times you also have such noce features as over current limit set... so if something ever seizes up again it won't take the gear train out. Automation interface is also extremely easy.

Bodine motors suck big time... thats why Stong no longer uses them. The Solid State Drive allows exact speed adjust with very little drift over two hours. Even though they are not synchronus they can be adjusted so exact that interlock is easy if necessary.

Mark