Troubleshooting - Chamberlain LiftMaster Professional SW420 Manual

Light duty swing gate operator
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Symptom
Possible Causes
No Stop Control.
Operator fails to
run.
Fault in the operator. Check
the yellow diagnostic LED at
the top right of the GL board
next to the programming dip
switches.
An accessory is active or
malfunctioning. Check the red
input status LEDs, D11-D31.
Improper J4 Connector Wiring
(Master/Second)
Low or no high voltage power. Measure the incoming voltage at the unit's on/off switch. It should be within
Low or no low voltage power.
No LEDs illuminated on GL
board.
The relays chatter
Low secondary (low voltage)
when the operator
power.
begins to move.
The operator runs
Low primary (high voltage)
slow and/or trips
power.
the internal
overload.
Problem in the motor.
Motor runs but
Damaged or imptoperly
gate doesn't move.
tensioned belt/drive chain.
T R O U B L E S H O O T I N G
Check the green LED (D17) on GL board. If the green LED is off, check to
make sure a stop control has been installed across terminals J1-3 & J1-5 of
the GL board.
If the yellow LED blinks six times there is a master/second unit
communication failure. If operator is a single unit make sure there is a
jumper across terminals 11 and 12. If operator is in a dual gate
configuration make sure that the communication wiring between the two
units is undamaged and complete.
If the yellow light is solid the board needs to learn the motor. Follow the
directions on page 22.
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.
Stand-alone Operators: make sure there is a jumper installed across the J4
connector.
Master/Second Operation: Make sure that the master/second wiring is
installed correctly and is intact (not damaged).
5% of the operator's rating when running. Make sure that the proper wire
gauge was used for the distance between breaker and operator by
consulting the wiring specifications section on page 14 of this manual.
Measure the voltage at terminals R1 & R2 in the operator. This voltage
should be within 5% of 24Vac. If the high voltage power is good and the low
voltage power is bad, check transformer wiring and replace transformer.
If both primary and secondary power is good, check to make sure that the J2
connector is making good contact with the pins on the GL board. If all is
good replace GL board.
Measure the voltage at terminals R1 & R2 in the operator. This voltage
should be within 5% of 24Vac. If the high voltage power is good and the low
voltage power is bad, check to make sure the circuit breaker is not tripped
and that the correct primary tap is used on the transformer. If breaker and
tap are correct replace the transformer.
Measure the incoming line voltage at the unit's on/off switch as well as the
meter base or sub panel. Make sure there is not a major change in voltage.
The voltage at the operator should be within 5% of the operator's rating
when running.
Check the number of amps currently being drawn from the panel, make sure
that the total power being drawn does not exceed the panel's rating.
Make sure that the proper wire gauge was used for the distance between
breaker and operator by consulting the wiring specifications section on page
14 of this manual.
Perform a visual inspection of the motor. Examine the motor's labels for any
distortion or signs of over heating. Replace the motor if it is humming,
grinding or making excessive noise. NOTE: Repeated motor problems
indicate poor primary power.
Make sure that the operator's belt/drive chain is intact and tensioned
correctly.
25
Solution

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