Chamberlain JDC Manual page 48

Troubleshooting (continued)
Symptom
LCD wall control
is off or not
functioning
(display shows
nothing or is unlit,
and wall control is
unresponsive)
(end)
Main board DC
IN fuses blow
immediately upon
powerup
Door moves in
wrong direction
when pressing up/
down buttons
(ONLY applies to
units with Battery
Backup)
Unit reports that it
is on battery power
even when AC
power is present
Possible Causes Diagnosis
Faulty wiring Perform this test only after verifying
main board WALL CTRL terminals.
Verify wall control wiring:
Disconnect wires from wall control
and measure the DC voltage on
the wiring at the end near the wall
control.
If voltage is not between 11 and 13
volts DC, wiring is faulty.
Faulty wall control Perform this test only after verifying
wall control wiring.
Check voltage at wall control:
With a voltmeter, test for 12VDC at
the screw terminals on the rear of
the wall control. If 12V is present and
wall control is not active, wall control
is faulty.
If 12V is absent only when the wall
control is connected, wall control
may have internal short circuit.
Stray wiring/metal Visually inspect E-box. Check for
contacting main any metallic objects or bare wires
board that may be inadvertently touching
the main board.
Internal short on Turn off AC power. Disconnect all
main board wiring from main board except DC
IN power wiring. Replace fuses and
reapply power. If fuses still blow
immediately, fault is in main board.
Reverse mounting Check the setting for the reverse
mode configured mounting mode (reverse limits)
wrong (reverse
limits)
Wiring for Check that open button is
open and close connected to OPEN terminal and
terminals swapped close button is connected to CLOSE
(does not apply to terminal.
LCD wall control)
AC power path Disconnect batteries, check if
issues powerhead main board powers off.
AC input voltage Check whether the transformer
mis-selected connector is plugged in to the
(120V/240V connectors on the EMI filter board
models only) marked '120V' or '240V.'
Verify this matches the input AC
voltage supplied to the operator.
AC power out of Verify input AC voltage:
range Measure AC voltage between 'L1'
and 'L2' terminals at EMI filter board
input connector. Verify voltage is
within specifications.
If voltage is outside specifications,
see resolution.
48
Resolution
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 or repair
wall control wiring.
Replace faulty wall control.
Prevent metallic objects or bare
wires from touching the main board.
Turn power off and replace fuses,
then re-apply power.
replace main board
ensure the setting is correct
Correct wiring.
If powerhead main board loses
power, leave batteries disconnected
and follow troubleshooting for
'Powerhead main board is off'
Note that if incorrect voltage is
applied to the operator, damage to
the operator electronics may have
occurred.
Ensure voltage selection is correct
and verify operator functionality.
Ensure the circuit supplying the
operator is the correct voltage class
for the operator (e.g. 120V, 240V,
or 480V)
If voltage is out of specification for
the circuit, consult an electrician.