Chamberlain LiftMaster PROFESSIONAL SECURITY+ 1280LMC-R Manuel Du Propriétaire page 25

ADJUSTMENT STEP 2
Adjust the Force
Force adjustment controls are located on the right
panel of the motor unit. Force adjustment settings
regulate the amount of power required to open and
close the door.
If the forces are set too light, door travel may be
interrupted by nuisance reversals in the down
direction and stops in the up direction. Weather
conditions can affect the door movement, so
occasional adjustment may be needed.
The maximum force adjustment range is about
3/4 of a complete turn. Do not force controls
beyond that point. Turn force adjustment controls
with a screwdriver.
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 FORCES
1. Test the DOWN (close) force
• Grasp the door bottom when the door is about
halfway through DOWN (close) travel. The door
should reverse. Reversal halfway through down
travel does not guarantee reversal on a one-inch
obstruction. See Adjustment Step 3, page 26.
If the door is hard to hold or doesn't reverse,
DECREASE the DOWN (close) force by turning
the control counterclockwise. Make small
adjustments until the door reverses normally. After
each adjustment, run the opener through a
complete cycle.
• If the door reverses during the down (close)
cycle and the opener lights aren't flashing,
INCREASE DOWN (close) force by turning the
control clockwise. Make small adjustments until the
door completes a close cycle. After each
adjustment, run the opener through a complete
travel cycle. Do not increase the force beyond the
minimum amount required to close the door.
2. Test the UP (open) force
• Grasp the door bottom when the door is about
halfway through UP (open) travel. The door should
stop. If the door is hard to hold or doesn't stop,
DECREASE UP (open) force by turning the control
counterclockwise. Make small adjustments until the
door stops easily and opens fully. After each
adjustment, run the opener through a complete
travel cycle.
• If the door doesn't open at least 5 feet,
INCREASE UP (Open) force by turning the control
clockwise. Make small adjustments until door
opens completely. Readjust the UP limit if
necessary. After each adjustment, run the opener
through a complete travel cycle.
WARNING
Without a properly installed safety reversal system,
persons (particularly small children) could be
CAUTION
SERIOUSLY INJURED or KILLED by a closing garage
door.
• Too much force on garage door will interfere with
proper operation of safety reversal system.
• NEVER increase force beyond minimum amount
required to close garage door.
• NEVER use force adjustments to compensate for a
binding or sticking garage door.
• 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 one-inch high object (or 2x4 laid flat) on
floor.
Force Adjustment Controls
RIGHT PANEL
9
7
5
Kg
FORCE ADJUSTMENT LABEL
25
1 2 3
9 9
1 1
7 3 7 3
5 5
KG
KG
9
1 1
3 7 3
5
Kg