Chamberlain Liftmaster Security+ 3900PLD Owner's Manual page 15

INSTALLING THE BRACKETS
Be sure power to the operator is disconnected. Install
and align the brackets so the safety reversing sensors will
face each other across the door, with the beam no higher
than 6" (15 cm) above the floor. They may be installed in
one of three ways, as follows.
Door track installation (preferred) (Figure 1):
• Slip the curved arms over the rounded edge of each door
track, with the curved arms facing the door. Snap into
place against the side of the track. It should lie flush, with
the lip hugging the back edge of the track, as shown in
Figure 1.
If your door track will not support the bracket securely,
wall installation is recommended.
Wall installation (Figure 2 and 3):
• Place the bracket against the wall with curved arms
facing the door. Be sure there is enough clearance for
the sensor beam to be unobstructed.
• If additional depth is needed, an extension bracket
(See Accessories) or wood blocks can be used.
• Use bracket mounting holes as a template to locate and
drill (2) 3/16" diameter pilot holes on the wall at each
side of the door, no higher than 6" (15 cm) above
the floor.
• Attach brackets to wall with lag screws (Not provided).
• If using extension brackets or wood blocks, adjust right
and left assemblies to the same distance out from the
mounting surface. Make sure all door hardware
obstructions are cleared.
Floor installation (Figure 4):
• Use wood blocks or extension brackets (See
Accessories) to elevate sensor brackets so the lenses
will be no higher than 6" (15 cm) above the floor.
• Carefully measure and place right and left assemblies at
the same distance out from the wall. Be sure all door
hardware obstructions are cleared.
• Fasten to the floor with concrete anchors as shown.
HARDWARE SHOWN ACTUAL SIZE
Carriage Bolt
1/4"-20x1/2"
Wing Nut Staples
1/4"-20
Figure 1
DOOR TRACK MOUNT (RIGHT SIDE)
Door
Track
Lip
Sensor
Bracket
Figure 2
Figure 3
(Provided with
Extension
Bracket)
Figure 4
15
Indicator
Light
Lens
WALL MOUNT (RIGHT SIDE)
Fasten Wood Block to Wall with
Lag Screws (Not Provided)
Indicator
Sensor
Light
Bracket
Lag Screws
(Not Provided)
Lens
WALL MOUNT (RIGHT SIDE)
Extension
Bracket
(See Accessories)
(Provided with
Extension Bracket)
Sensor
Bracket
Indicator
Light
Lens
FLOOR MOUNT (RIGHT SIDE)
Attach with
Concrete Anchors
(Not Provided)
Lens
Indicator
Light
Sensor
Bracket