LiftMaster ATSW Mode D'emploi page 24

Power
2 Ensure the Safety Reversing Sensors (Including the Light Curtain)
are Aligned
The door will not close if the sensors have not been installed and aligned correctly.
When the light beam is obstructed or misaligned while the door is closing, the door will reverse. If the door is already
open, it will not close. The sensors can be aligned by loosening the wing nuts, aligning the sensors, and tightening the
wing nuts.
1. Check to make sure the LEDs in both sensors are glowing steadily. The LEDs in both sensors will glow
steadily if they are aligned and wired correctly.
Indicator
Light
6" (15 cm) max. above floor
If the emitter sensor and receiver sensor indicator lights do not glow steadily after installation, check for:
If the receiver sensor indicator light is off or flashing (and the invisible light beam path is not obstructed),
check alignment of the sensors and/or for an open wire to the receiver sensor.
If the emitter sensor and receiver sensor indicator lights are both glowing steadily but interrupting the
photoelectric sensors does not cause the door to reverse when closing, check both sensors to make sure
one sensor is the emitter and the other is a receiver sensor as indicated on the sensor housing.
NOTES:
3 Ensure the Door Control is Wired Correctly
Indicator
If the door control has been installed and wired correctly, the LED behind the push button will blink.
Light
6" (15 cm) max. above floor
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Photoelectric sensor alignment
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Obstruction
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Power to the operator
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A short or broken wire
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Incorrect wiring between photoelectric sensors and the operator
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Direct sunlight to the receiver sensor may prevent the operator from closing even when both the emitter
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and receiver indicator lights are illuminated. Swapping the position of the emitter and receiver sensors will
resolve this issue.
Professional service is required if the operator closes the door when the photoelectric sensors are
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obstructed.