Chamberlain LiftMaster Professional SW420 Manual page 26

Symptom
Failure to cycle power after
Master or Second
setup.
operator is not
functioning
The communication wiring may
properly.
be damaged or improperly
wired for dual gate operation.
The master or second unit is
not programmed correctly.
Operator runs but Entrapment (Force Pot)
incorrectly set.
then stops and
reverses direction. Gate is binding or not running
smoothly.
Observe red LEDs D29 and
D31.
The Hall Effect Sensor is not
aligned/adjusted correctly.
The operator Check the red input status
opens immediately LEDs, D11-D31, for indication
upon power up of an active or malfunctioning
and does not accessory.
close.
Programming Check the save switch on
changes do not switch S1-1.
effect the gate.
Open photo eye Open obstruction input is
reverses gate programmed incorrectly.
closed when
activated during
opening.
Gate does not Close obstruction input is
activate the timer programmed incorrectly.
to close after the
close photo eye is
broken.
Radio terminals R1-4 are
Radio controls
factory configured for
will close gate
residential (Open & Close)
from the open
radio function.
limit
T R O U B L E S H O O T I N G c o n t i n u e d
Possible Causes
The power to each unit must be cycled in order to initiate proper
master/second communication if the operators were previously in stand-
alone mode.
Make sure that the communication wire that is used is twisted pair and not
run in the same conduit with any power wiring. Failure to do so will result
in interference across the master/second communication line.
Review program settings pages 23-24 and check both the master and
second for proper programming.
This pot must be set so that the gate will run smoothly normally and reverse
when encountering and obstruction. See page 22.
Disconnect the gate from the operator and swing the gate open and close by
hand at normal operating speed. Make sure that the gate swings smoothly
and does not bind. If the gate is hard to move or binds repair the gate.
Both LEDs will indicate the activation of entrapment protection devices on
terminals J1-9 & J1-10 on the GL board. Remove the devices and retest. If
the operator now runs without fault, check those accessories as well as their
wiring.
Make sure that the sensor is adjusted so that it is within 20 thousandths of
an inch or as close to the magnets located on the gearbox pulley as possible
without coming into contact with them or the pulley.
Replace the sensor if it is adjusted correctly but continues to fail.
If any red LEDs are on, check the corresponding input. An installed
accessory may be wired incorrectly or malfunctioning. Remove the
accessory and test the operator.
If the switch S1-1 is in the on position any subsequent programming
changes will not affect the gate. To make programming changes, switch
S1-1 off, make desired changes, and then switch S1-1 on.
The open obstruction input has been programmed to function with gate
edges not photo eyes. Refer to page 24 and reprogram the obstruction
inputs for correct operation.
The close obstruction input has been programmed to function with gate
edges not photo eyes. Refer to page 24 and reprogram the obstruction
inputs to match the accessories that are installed on the operator.
Configure terminals R1-4 for residential radio function by performing
the following modifications:
1. Locate and disconnect the end of the wire running to terminal J1-1
from R4.
2. Connect the end of wire removed from J1-1 to J1-6. Refer to page 36.
Solution
26