Chamberlain 1280 - 1/2 HP - Manual (Page 24)

Adjustment Step 1
Adjust the UP and DOWN Limits
Do not make any limit adjustments until the
Safety Reversing Sensors are completely
installed.
24
Limit adjustment settings regulate the points at
which the door will
stop when moving up or down.
The door will stop in the up direction if anything
interferes with door travel. The door will reverse in
the down direction if anything interferes with the
door travel (including binding or unbalanced doors).
To operate the opener, press the Door Control push
bar. Run the opener through a complete travel
cycle.
• Does the door open and close completely?
• Does the door stay closed and not reverse
unintentionally when fully closed?
If your door passes both of these tests, no limit
adjustments are necessary unless the reversing
test fails (see page 26).
Adjustment procedures are outlined below. Run
the opener through a complete travel cycle after
each adjustment.
Repeated operation of the opener during
adjustment procedures may cause the motor to
overheat and shut off. Simply wait 15 minutes
and try again.
Read the procedures carefully before proceeding to
Adjustment Step 2. Use a screwdriver to make limit
adjustments.
Left Side
Panel
Limit Adjustment Screws
INCREASE
DOWN
TRAVEL
INCREASE
UP
TRAVEL
How and When to Adjust the Limits
If the door does not open completely
but opens at least five feet
Increase up travel. Turn the UP limit adjustment
screw clockwise. One turn equals 2" of travel.
If door does not open at least 5 feet: Adjust the
UP (open) force as explained in Adjustment Step 2.
If the door does not close completely
Increase down travel. Turn the DOWN limit
adjustment screw counterclockwise. One turn
equals 2" of travel.
If door still won't close completely, try lengthening
the door arm. (Page 22.)
If you have adjusted the door arm to the maximum
length and the door still will not close completely,
lower the header bracket. See Installation Step 1,
pages 8/9.
If the opener reverses in fully closed position
Decrease down travel. Turn the DOWN limit adjustment
screw clockwise. One turn equals 2" of travel.
If the door reverses when closing and
there is no visible interference to travel cycle
If the opener lights are flashing, the Safety Reversing
Sensor is obstructed. Remove the obstruction.
Test the door for binding: Pull the manual release
handle. Manually open and close the door. If the door
is binding, call for garage door service. If the door is
not binding or unbalanced, adjust the DOWN (close)
force. See Adjustment Step 2.
Adjustment Section: Pages 24 – 26
Improper adjustment of the travel limits will
interfere with the proper operation of the safety
reverse system.
The door might not reverse
when required and could seriously injure or kill
someone under it. Test the safety reverse
system following all adjustments to the travel
limits. See page 26.
INCREASE
DOWN
TRAVEL
Limit Adjustment Label
INCREASE
UP
TRAVEL
WARNING
Limit Adjustment Label