Issues with Century JJ Projector Running 70mm Film

[Chris Horak]

I have a Century JJ projector running 70mm film and am having an issue engaging the projector motor. A slight pulse/movement is observed but the projector motor does not engage until after 4-5 motor start attempts. Motor switch has been swapped but the problem still occurs.

Is this a motor issue or is it an intermittent issue? Once the projector is running the intermittent runs properly.

[Sam Chavez]

What happens when you roll the projector over by hand? Does it turn over easily? With or without film threaded?

Could be the the gate tension is way too high. Just a guess to get this topic rolling as it were.

[Leo Enticknap]

Bad motor run capacitor?

[Jim Cassedy]

When you say "the motor swtich has been swapped"- do you mean the switch you operate to
start the projector motor, or are you talking the centrifugal swtich inside the motor?
I'm with Leo in that it could be a bad start or run capacitor, OR the centrifugal swtich inside
the motor isn't working right. I've had one "stick" on me once years ago and I was able to
take it out & clean it up & it worked fine- - but you have to pull the motor apart to do that.

[John Eickhof]

if equipped with a century slo-start box (approx 4" sq attached to motor) check the slide-on lugs internally and look for a loose lug, also the precision resistor may have a loose lead wire, also the starting cap may be flat, if so get a replacement. all direct drive centurys had this box especially later jjs

[Brad Miller]

We really need to know the answers to Sam's questions first. Also if the mechanism runs smooth with no film threaded, how does it run with 35mm film? Some photos would really help as well too, as there were a number of different gate designs and there is a very good chance you have an incorrect gate/trap mated together that will cause significant damage to the 70mm film.

[Mark Gulbrandsen]

We really need to know the answers to Sam's questions first. Also if the mechanism runs smooth with no film threaded, how does it run with 35mm film? Some photos would really help as well too, as there were a number of different gate designs and there is a very good chance you have an incorrect gate/trap mated together that will cause significant damage to the 70mm film.

I have only ever run into two types in 40+ years. The original, which was a solid curved trap and gate, Like the Model H 35mm had, and the later and last version which was a solid gate with bands in the trap. Of course there was a motorized version as well... but the trap was basically the same, just modified for the different aperture plate and a motor..

[Sam Chavez]

There are all sorts of FrankenCentury JJ's out there these days. Sync motors, slow starts, aftermarket gates and traps, you name it. I've seen some where the difference in focus and tension between 35 and 70 requires the lens carriage to be repositioned. This isn't a dowel pinned projector. You can pretty much put it together any way you like. Wrong gears, wrong pulley's.

Which is why I ask the basic questions first.

[Steve Guttag]

There was one era where they switched which gears were fiber/steel on the main drive set (I don't think they did the same thing on the shutter gears though). The JJ had lots of evolutions.

[Sam Chavez]

There was also Poly V belt drive or Gilmer belts; Standard drive thru the sound head, or direct drive thru the picture head with a skimpy little speedometer cable drive to the soundhead and onto the take up clutch.

Amazingly, it worked better than it looked.

Then there were the Indian and Mexican variants as well as the Westex version. And the parts were more or less interchangeable. Yankee ingenuity from our agricultural legacy.

[Rick Raskin]

The kicker here is what behavior do you see with no film threaded. If the machine still exhibits the same issue look for a bad start capacitor or if equipped, a faulty start relay (which I once experienced on a DP70).