Chamberlain 3840 Garage Door Opener User Manual


 
24
Black Button
Purple Button
LED
Push Purple button
twice to enter
unit into Force
Adjustment Mode
Without a properly installed safety reversal system, persons
(particularly small children) could be 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 use force adjustments to compensate for a binding or
sticking garage door.
• 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 2x4 laid flat) on floor.
Figure 2
Figure 1
or
Figure 3
LED
Black Button
Purple Button
Side Panel
LOCK
LIGHT
ADJUSTMENT STEP 2
Set the Force
The force setting measures the amount of force
required to open and close the door.
1. Push the purple button twice to enter into the Force
Adjustment Mode. The LED will flash quickly.
2. Push the door control or programmed remote control.
The door will close (DOWN).
3. Push the door control or programmed remote control
again. The door will open (UP).
4. Push the door control or programmed remote control a
third time to close the door (DOWN).
The LED will stop flashing when the force has been
programmed.
The door must travel through a complete cycle, up and
down, in order for the force to be set properly. If the garage
door opener cannot open and close the door fully, inspect
the door to ensure that it is balanced properly and is not
sticking or binding.
If the door is not stopping exactly where you would like it,
repeat Program the Travel Limits.