LiftMaster 3840 3840 Manual - Page 13

MOUNTING THE SAFETY SENSORS • Slide a 1/4"-20x1/2" carriage bolt head into the slot on each sensor. Use wing nuts to fasten sensors to brackets, with lenses pointing toward each other across the door. Be sure the lens is not obstructed by a bracket extension (Figure 5). • Finger tighten the wing nuts. Recommended Wire Routing 1. Using insulated staples, run the wires from both sensors to the rail at the door header (Figure 5A). 2. Run the wires through wire clips at the top of the rails. NOTE: If your access door is near the garage door, you may choose to install the door control at this time and run the door control wire along the rail with the sensor wires. 3. Separate the white and white/black wires. Strip 7/16" (11 mm) of insulation from the end of the sensor wires. Twist like colored wires together. Connect the bell wire from safety reversing sensors to the quick-connect terminals: white wires to the white terminal and white/black wires to grey terminal (Figure 5B). HARDWARE SHOWN ACTUAL SIZE Carriage Bolt 1/4"-20x1/2" Wing Nut 1/4"-20 Staples Cable Figure 5A Sensor Wire Wire Clips Rail Figure 5B SAFETY REVERSING SENSORS CONNECTIONS Quick-Connect Terminals Left Side Panel Strip wire 7/16" 7/16" (11 mm) White/Black Wire White Wire To release or insert wire, push in tab with screwdriver tip White Grey Antenna Safety Reversing Sensor Invisible Light Beam Protection Area Figure 5 Bracket Wing Nut 1/4"-20 Carriage Bolt 1/4"-20x1/2" Lens Bell Wire 13