Chamberlain JDC Manual page 49

Troubleshooting (continued)
Symptom
Door runs slowly/at
half speed
Operator turns off
despite backup
battery being
connected
Operator runs
momentarily then
stops in limit learn
mode
Possible Causes Diagnosis
Wall control If communications to the wall
disconnected or control is absent, system will run at
damaged half speed.
Dead or worn Low battery voltage
batteries
Blown battery Visually inspect battery fuses or
fuses on main check continuity
board
Encoder wiring Inspect encoder cable for
fault disconnection, bad connection, cut
cable, etc.
Encoder fault or Go to limit learn process. Number
encoder interface displayed while in door limit learn
fault mode is the encoder position.
Jog door several inches in either
direction and release button.
Number displayed should change.
Make sure to cancel changes or set
limit again when finished.
49
Resolution
LCD Wall control is strongly
recommended to be connected.
If it is desired to run the system
without a wall control, temporarily
or permanently, the system can be
returned to full speed operation by
replacing the wall control wiring with
a jumper wire.
If the wall control is present but not
functioning, see 'LCD wall control is
off or not functioning'
Allow batteries to recharge
Replace worn out batteries.
Batteries must both be replaced
together. Do not mix old and new
batteries.
If fuses are blown, replace both
fuses together
Correct any issues found with
encoder wiring
If encoder position does not change
with door movement, the encoder,
encoder wiring, and powerhead
main board are suspect. Check all
three for any visible damage.
Attempt power cycling and restoring
factory defaults.
Replace or repair suspected faulty
components.