Chamberlain JDC Manual page 47

Troubleshooting (continued)
Symptom
LCD wall control
is off or not
functioning
(display shows
nothing or is unlit,
and wall control is
unresponsive)
(continued)
Possible Causes Diagnosis
Multiple LCD wall Only one LCD wall control is
controls wired to a supported per operator. Check that
single operator. only one is connected to the WALL
CTRL terminals on the powerhead
main board.
Wall control is Confirm that wall control wiring is
wired to incorrect run to the WALL CTRL terminals on
terminals on the the powerhead main board.
powerhead main
board.
No power to Verify MAIN PWR LED is lit on the
powerhead main mainboard. If if it unlit, main board
board may not have power.
Wall control circuit Test for wall control short circuit:
shorted Power cycle the operator.
Check WALL CTRL LED on
powerhead main board.
If LED is unlit, a short circuit is
detected on the WALL CTRL
terminals by the main board and the
wall control is disabled.
Bad connection Visually inspect the wiring
between wiring connections to the wall control
and wall control screw terminals. Wires should be
sandwiched between the screw and
the exposed metallic pads on the
circuit board. Ensure insulated part
of wire is not caught between screw
and circuit board.
No voltage output Verify main board WALL CTRL
from powerhead terminals:
main board WALL Disconnect wall control wires.
CTRL terminals Measure DC voltage at WALL CTRL
terminals.
Voltage should be between 11 and
13V DC.
47
Resolution
Disconnect any additional LCD wall
controls and wire just one LCD wall
control.
If additional control stations are
desired, use the SBC or OPEN,
CLOSE, and STOP terminals instead.
Move wall control wiring to the
WALL CTRL terminals
Follow troubleshooting for symptom
'Powerhead main board is off'
Turn off AC power and disconnect
batteries (if present). Remove wall
control wiring from main board
terminals. Restore batteries and AC
power.
If WALL CTRL LED remains unlit,
short circuit may be internal to main
board. Replace main board.
If WALL CTRL LED is blinking, short
is in wall control wiring or wall
control. Reconnect wiring to main
board. Disconnect wall control from
wiring. Repeat test.
If WALL CTRL LED is blinking,
short is in wall control. Replace wall
control.
If WALL CTRL LED is off, short is
in wiring. Check wiring and correct
the issue.
Correct any issues noted during
inspection
If voltage is absent or out of range,
turn off power to operator and
disconnect batteries if present. Wait
30 seconds and then reconnect
batteries and reapply AC power.
If fault persists, replace main board