Film-Tech Forum ARCHIVE: Eprad Co-operator continues to cycle

This is topic Eprad Co-operator continues to cycle - FIX in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Kenneth Wuepper (Member # 1174) on 05-06-2007, 05:18 PM:

Just finished servicing an old Co-operator for a single screen house. The drum would continue to coast and then recycle the projector, house lights and curtains continuously.

The first thought was the microswitch for the drum motor. NOT! By applying a small drag on the cam shaft, it was apparent that the motor shaft was "coasting" after the power went off.

Refer to the diagram of the unit and discover that Eprad anticipated this problem and solved it by adding a DC brake for the drum motor. A 1N4005 diode and 2.2K resistor are in series and across the run contacts of relay KS for the drum motor.

The resistor had failed and so the motor was free to coast past the stop detents. Installing a new diode and resistor (2 Watt Carbon) fixed the problem. These components are buried at the bottom of the chassis pan and are soldered to a terminal strip there. If you have this problem, you will notice that the resistor is enclosed in shrink wrap with the diode sticking out one end.

Hope this is helpful.
KEN [Wink]

Posted by Jack Ondracek (Member # 1466) on 05-07-2007, 04:21 AM:

Thanks for the info on that, Ken. I still take care of a couple of them. I just figured that with the gearing, and lack of any flywheel on that clock motor, coasting wouldn't be an issue.

Posted by Tim Reed (Member # 137) on 05-07-2007, 05:49 PM:

Oh, it does coast. Very much so.

Posted by Louis Bornwasser (Member # 3063) on 05-07-2007, 08:07 PM:

I am proud to say....."All of my Co-operators are no longer required to Co-operate!!!" Louis