The Purpose of the Residential Jackshaft Opener Cable Tension Monitor

The cable tension monitor prevents the cables from being thrown by automatically reversing the opener when cable slack is present. The cable tension monitor must be installed in order for the Residential Jackshaft Opener (RJO) to run. If your door cables continue to come off of the drum, please refer to your owner's manual and verify the Cable Tension Monitor has been installed properly.

While the spring will generally keep tension on the cable, there are a few reasons why a cable could come off of the drum.

• A broken torsion spring. If your torsion spring breaks the cables will lose tension and may become tangled or come off the drum.
• ​If the speed of a closing garage door is slower than that of the opener, or the door encounters and obstruction when closing. While the Cable Tension Monitor should identify slack in the cable and reverse the door to the open position, there is a slight possibility if the door stops abruptly, the cable may come off of the drum.
• Trying to manually open door while it is connected to the RJO
• Using tapered or reverse-wound drums

Once your cables have come off of the drum, you will be unable to open or close the door. In order to have the door in working condition, a trained door technician must reinstall the cables and safety check the door.