Film-Tech Forum ARCHIVE: Franklin Designs TDM-1025 masking motor control issue

This is topic Franklin Designs TDM-1025 masking motor control issue in forum Digital Cinema Forum at Film-Tech Forum ARCHIVE.

To visit this topic, use this URL:
https://ft-forum.com/ft/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=16;t=003730

Posted by Ken Lackner (Member # 1002) on 06-28-2019, 03:33 PM:

Side-movable masking using a TDM-1025 motor. When opened all the way up to Scope, when I press the Flat button on the automation or issue a Flat cue, the masking closes in a little towards the Flat position and then stops. Press the button again, it moves a little more. Again, and again. About four times, total, for it to reach it's final resting position. Same for moving towards Scope from Flat. At first I just thought the limits need to be adjusted, but it doesn't seem like that would cause this problem. Once the motor reaches the assigned limit, it would not continue to travel when the input were pulsed. I don't believe it's a wiring problem, as the issue happens when I jump the terminals on the control board at the motor.

Any ideas?

Posted by Frank Cox (Member # 6258) on 06-28-2019, 03:36 PM:

Any chance that the masking is getting jammed in the track?

Posted by Sean McKinnon (Member # 612) on 06-29-2019, 09:06 AM:

Sounds to me like something is causing the motor to stop even though it is being commanded on. I would measure the output from the controller to make sure that the power to the motor isn't dropping out then I would try to run the motor unloaded and see what happens. My guesses would be

1. Controller failure
2. Motor failure
3. Mechanical problem in the rigging.

In that order

Posted by Steve Moore (Member # 4753) on 06-29-2019, 07:52 PM:

The motors I have encountered, have a piece of threaded rod, driven by a gear/belt from the motor, somewhere near the masking cable flywheel. When the motor turns, so does the threaded rod, which has a lever attached to it, which moves a distance left or right, along the thread and and when it reaches the limit set, this lever touches on a microswitch which cuts the motor. If these motors work the same way, then one of the microswitches could be jammed or something is pressing on the microswitches with each revolution of the motor?
The motors I have come across are 40+ years old, with this simple end stop switch. Are modern ones microprocessor controlled now with some counting going on?

Posted by Mark Gulbrandsen (Member # 72) on 06-30-2019, 03:14 PM:

Yes, they are sorta just adapted Garage Door Openers. Mulones crap was much the same. Check the micro (limit switches) carefully. Switches made today are garbage and short lived because the contacts contain no cadmium.

Mark