Chamberlain 248730DM, Assembly & Installation Manual

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Without a properly installed safety reversal system, persons
(particularly small children) could be SERIOUSLY INJURED or
KILLED by a closing garage door.
• Incorrect adjustment of garage door travel limits will interfere
with proper operation of safety reversal system.
• If one control (force or travel limits) is adjusted, the other
control may also need adjustment.
• After ANY adjustments are made, the safety reversal system
must be tested. Door must reverse on contact with 1-1/2"
(3.8 cm) high object (or 2 x 4 laid flat) on floor.
To prevent damage to vehicles, be sure fully open door
provides adequate clearance.
WARNING
CAUTION CAUTION WARNING
WARNING
WARNING WARNING
CAUTION WARNING
WARNING
ADJUST THE UP AND DOWN TRAVEL LIMITS
Limit adjustment settings regulate the points at which the
door will stop when moving up or down.
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 Adjustment Step 3).
Adjustment procedures are outlined below. Read the
procedures carefully before proceeding to Adjustment
Step 2. Use a screwdriver to make limit adjustments. Run
the opener through a complete travel cycle after each
adjustment.
NOTE: Repeated operation of the opener during
adjustment procedures may cause the motor to overheat
and shut off. Simply wait 15 minutes and try again.
NOTE: If anything interferes with the door’s upward travel,
it will stop. If anything interferes with the door’s downward
travel (including binding or unbalanced doors), it will
reverse.
HOW AND WHEN TO ADJUST THE LIMITS
• If the door does not open completely but opens at
least 5 feet (1.5 m)
:
Increase up travel. Turn the UP limit adjustment screw
clockwise. One turn equals 2" (5 cm) of travel.
NOTE: To prevent the trolley from hitting the cover
protection bolt, keep a minimum distance of 2-4"
(5-10 cm) between the trolley and the bolt.
• If door does not open at least 5 feet (1.5 m):
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" (5 cm) of
travel.
ADJUSTMENT LABEL
Cover Protection Bolt
2-4"
(5 cm-
10 cm)
Left Side Panel Limit Adjustment Screws
Turn either limit adjustment screw the direction
of the arrow to increase trolley travel, turn in
the opposite direction to decrease travel
ADJUSTMENT STEP 1
• If the opener reverses in fully closed position:
Decrease down travel. Turn the DOWN limit adjustment
screw clockwise. One turn equals 2" (5 cm) 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
Sensors are either not installed, misaligned, or
obstructed.
ADJUSTMENT