Liftmaster 3950 Owners Manual 114A4066C

2014-07-19

: Liftmaster Liftmaster-3950-Owners-Manual liftmaster-3950-owners-manual liftmaster pdf

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The Chamberlain Group, Inc.
845 Larch Avenue
Elmhurst, Illinois 60126-1196
www.liftmaster.com

DOOR OPERATOR
Model 3950

Co
m

For Light Duty Commercial Use

tib

le with

Owner’s Manual
■

Please read this manual and the enclosed safety materials carefully!

■

The door WILL NOT CLOSE unless The Protector System® is connected and properly aligned.

■

Periodic checks of the operator are required to ensure safe operation.

■

The model number label is located behind the hinged door of your operator.

■

DO NOT exceed 10 complete cycles of door operation per hour.

■

DO NOT use with sectional type doors.

■

This manual is to be left with the property owner.

YEAR

WARRANTY

Serial #
(Located on electrical box cover)
Installation Date

TABLE OF CONTENTS
Introduction

2-4

Operation

16-18

Safety symbol review and signal word review . . . . . . . . . . . . . . .
Preparing your door . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Carton inventory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Hardware inventory. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

2
3
3
4
4

Operation safety instructions . . . . . . . . . . . . . . . . . . . . . . . . . . .
Using your operator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Care of your operator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Having a problem? (Troubleshooting) . . . . . . . . . . . . . . . . . . . .
Diagnostic chart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Assembly

Programming

Attach the drive sprocket . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Attach mounting brackets. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Installation

19-20

To add or reprogram a hand-held
remote control (not provided) . . . . . . . . . . . . . . . . . . . . . . . . . . 19
To erase all codes from motor unit memory . . . . . . . . . . . . . . . 19
To add, program or change a keyless entry
PIN (not provided) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

6-12

Installation safety instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Install the door sprocket. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Mount the operator. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Attach the emergency release rope and handle . . . . . . . . . . . . . . 8
Install the single button control station . . . . . . . . . . . . . . . . . . . . 8
Electrical requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Install The Protector System® . . . . . . . . . . . . . . . . . . . . . . . . 10-12

Adjustment

16
16
16
17
18

Repair Parts

Installation parts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Motor unit assembly parts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

13-15

Accessories

Notes

Repair Parts and Service

Program the travel limits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Set the force . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Test The Protector System® . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
To open door manually. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Back Page

INTRODUCTION
Safety Symbol Review and Signal Word Review
This door operator has been designed and tested to offer safe service provided it is installed, operated, maintained and tested in strict
accordance with the instructions and warnings contained in this manual.
When you see these Safety Symbols and Signal Words on the
following pages, they will alert you to the possibility of serious
injury or death if you do not comply with the warnings that
accompany them. The hazard may come from something
mechanical or from electric shock. Read the warnings carefully.

Mechanical

When you see this Signal Word on the following pages, it will
alert you to the possibility of damage to your door
and/or the door operator if you do not comply with the cautionary
statements that accompany it. Read them carefully.

Electrical

Preparing Your Door
Before you begin:
• Remove any ropes connected to door.
• Raise and lower the door to ensure the door does not bind or
stick and is properly balanced. If your door binds, sticks or is
out of balance refer to the door manufacturer for more
information.
For live shaft type doors the drive shaft needs to extend 1-1/2"
beyond the door mount bracket.
• If the operator is mounted below 8 feet (2.5 m), a chain guard
must be installed to protect against possible injury. See
accessories page.

To prevent possible SERIOUS INJURY or DEATH:
• ALWAYS call a trained door systems technician if door
binds, sticks or is out of balance. An unbalanced door may
not reverse when required.
• NEVER try to loosen, move or adjust door, door springs,
cables, pulleys, brackets or their hardware, ALL of which are
under EXTREME tension.
• Disable ALL locks and remove ALL ropes connected to door
BEFORE installing and operating door operator to avoid
entanglement.
• DO NOT install operator below 6 feet (1.83 m).

To prevent damage to door and operator:
• ALWAYS disable locks BEFORE installing and operating the
operator.
• ONLY operate door operator at 120V, 60 Hz to avoid
malfunction and damage.
• DO NOT exceed 10 complete cycles of door operation per
hour.
• DO NOT run operator if the door is locked.
• Chain guard to be installed where the drive chain is exposed
lower than 8 feet (2.5 m).

Specifications
Volts . . . . . . . . . . . . . . . . . . . . . . . . .120 Vac - 60 Hz, ONLY
Current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.0 AMP
Rated Load . . . . . . . . . . . . . . . . . . . . . . . . . . . 325 in. lb/sec.
10 Cycles per Hour
Maximum Door Height . . . . . . . . . . . . . . . . . . . . . . . 12 feet
Maximum Door Size . . . . . . . . . . . . . . . . . . 14 feet x 12 feet
(not to exceed 168 sq./ft)

Carton Inventory
Note that accessories will depend on the model purchased. If
anything is missing, carefully check the packing material.

Your door operator is packaged in one carton which contains the
motor unit and the parts illustrated below.

Single Button Control
Station

2-Conductor Bell Wire
White & White/Red

Safety Reversing Sensor
Bracket (2)
Mounting Bracket (4)
12 Tooth Drive Sprocket
with Drive Chain

Operator

Door Sprockets

The Protector System®
(2) Safety Reversing Sensors
(1 Sending Eye and 1 Receiving Eye)
with 2-Conductor White & White/Black
Bell Wire attached

Safety Labels
and
Literature

Hardware Inventory
Installation Hardware
Tubular Spacer 1/2" (6)
Tubular Spacer 2" (3)
Cap Screw 1/4"-20 x 2" (1)
Nylock Lock Nut 1/4"-20 (1)
Hex Head Bolt 3/8"-16 x 4" (3)
Flat Washer 3/8" (3)
Serrated Flange Nut 5/16"-18 (3)
Carriage Head Bolt 1/4"-20 x 1/2" (2)

Self Taping Screw #10-32 (8)
Rope (1)
Handle (1)
Wing Nut 1/4"-20 (2)
Hex Drive Round Head Bolt 1/4"-20 x 1/2" (2)
Warning Tag for Release Handle (1)

ASSEMBLY STEP 1

Figure 1

Attach the Drive Sprocket

Output Shaft
Drive Sprocket

The drive sprocket can be installed on the right or left side of the
operator depending on your installation. The drive sprocket has
three holes to aid in the alignment of the drive sprocket with the
door sprocket.
1. Insert the drive sprocket into the output shaft.
2. Align the center holes in the drive sprocket with the hole in the
output shaft.
3. Insert bolts into the output shaft and the drive sprocket.
4. Finger tighten the bolts.

Bolt

ASSEMBLY STEP 2
Attach Mounting Brackets

Figure 2
Mounting Brackets

The operator can be mounted to the wall with the mounting
brackets provided. An optional guide mounting bracket is
available for purchase (see accessories).
1. Position two mounting brackets on each side of the operator.
2. Fasten the mounting brackets to the operator using the
self-threading screws (8) provided.

Operator

WARNING
INSTALLATION

IMPORTANT INSTALLATION INSTRUCTIONS
WARNING
To reduce the risk of SEVERE INJURY or DEATH:
1. READ AND FOLLOW ALL INSTALLATION WARNINGS AND
INSTRUCTIONS.
2. Install door operator ONLY on properly balanced and
lubricated door. An improperly balanced door may not
reverse when required and could result in SEVERE INJURY
or DEATH.
3. ALL repairs to cables, spring assemblies and other hardware
MUST be made by a trained door systems technician
BEFORE installing operator.
4. Disable ALL locks and remove ALL ropes connected to door
BEFORE installing operator to avoid entanglement.
5 Mount emergency release handle no higher than 6 feet
(1.83 m) above floor.
6. NEVER connect door operator to power source until
instructed to do so.

7. NEVER wear watches, rings or loose clothing while installing
or servicing operator. They could be caught in door or
operator mechanisms.
8. Install wall-mounted door control:
• within sight of the door.
• out of reach of children at minimum height of 5 feet
(1.5 m).
• away from ALL moving parts of the door.
9. Install the Entrapment Warning Placard next to the control
station in a prominent location.
10. Place manual release/safety reverse test label in plain view
on inside of door.
11. Upon completion of installation, test safety reversal system.
12. Install the operator at least 8 feet (2.5 m) or more above the
floor if the operator has exposed moving parts.

Figure 1

INSTALLATION STEP 1

Through Bolt

Install the Door Sprocket
Door

The instructions below are general and we recommend you refer
to the door manufacturer for specific instructions for your door.

Door
Sprocket

Live shaft type (Figure 1):
1. Slide the door sprocket onto the end of the door shaft.
2. Mark and drill a hole through the door shaft.
3. Attach the door sprocket to the door shaft with the through
bolt and nylock nut.
NOTE: Drive shaft must extend 1-1/2" beyond the door support
bracket.

Door Shaft
Nylock
Nut

Drum

Door Bracket
Door Sprocket

Dead shaft type (Figure 2):
1. Slide the door sprocket onto the end of the door shaft.
2. Slide the through bolts with flat washers into the door sprocket
with tubular spacers and attach to the door drum.
3. Secure the sprocket to the drum as shown.

Figure 2

Drum
Door
Sprocket

Flange Nut

Door

Door
Sprocket
Drum
Tubular
Spacer

Flat Washer

INSTALLATION STEP 2
Mount the Operator

To prevent possible SERIOUS INJURY or DEATH:
• Concrete anchors MUST be used if mounting bracket into
masonry.
• NEVER try to loosen, move or adjust door, springs, cables,
pulleys, brackets or their hardware, ALL of which are under
EXTREME tension.
• ALWAYS call a trained door systems technician if door
binds, sticks or is out of balance. An unbalanced door might
not reverse when required.
• Operator MUST be mounted at a right angle to the door
shaft.

The operator can be mounted to the wall with the mounting
brackets provided.
An optional guide mounting bracket is available for purchase
(see accessories).
Fasten the operator to the mounting surface using appropriate
method and hardware (not provided).
Anchors must be fastened to structural members only. Use
concrete anchors for masonry construction.
NOTE: Mounting the operator to drywall is not recommended.
1. Raise the operator to approximate mounting position, make
sure the drive sprocket is aligned with the door sprocket.
NOTE: If the drive and the door sprockets are not aligned, the
drive sprocket can be laterally adjusted by removing the bolt
from the drive sprocket.
2. Wrap the chain around the door and drive sprockets.
3. Connect the ends of the chain using the master link (provided).
4. Raise or lower the operator until the chain is taut (not tight).
Make sure the operator output shaft is parallel to door shaft
and sprockets are aligned.
5. Secure the operator to wall using appropriate method.
6. Tighten the drive sprocket bolts using a 5/32" Allen wrench.

Live Shaft

Chain

Mounting
Hardware
(not provided)

Operator

Dead Shaft

Chain

Mounting
Hardware
(not provided)

Operator

INSTALLATION STEP 3
Attach the Emergency Release Rope and Handle

To prevent possible SERIOUS INJURY or DEATH from a falling
door:
• If possible, use emergency release handle to disengage door
ONLY when door is CLOSED. Weak or broken springs or
unbalanced door could result in an open door falling rapidly
and/or unexpectedly.
• NEVER use emergency release handle unless doorway is
clear of persons and obstructions.

1. Thread one end of the rope through the hole in the top of the
red handle so “NOTICE” reads right side up as shown. Secure
with an overhand knot at least 1" (2.5 cm) from the end of the
rope to prevent slipping.
2. Thread the other end of the rope through the loop in the
emergency release cable.
3. Adjust rope length so the handle is no higher than 6 feet
(1.83 m) above the floor. Secure with an overhand knot.
NOTE: If it is necessary to cut the rope, heat seal the cut end with
a match or lighter to prevent unraveling.

Motor Unit
Emergency
Release Cable
Overhand
Knot

Rope

Emergency
Release Handle

NOTI
CE

Overhand
Knot

INSTALLATION STEP 4
Install the Single Button Control Station

To prevent possible SERIOUS INJURY or DEATH from
electrocution:
• Be sure power is not connected BEFORE installing door
control.
• Connect ONLY to 24 VOLT low voltage wires.
To prevent possible SERIOUS INJURY or DEATH from a
closing door:
• Install door control within sight of door, out of reach of
children at a minimum height of 5 feet (1.5 m) and away
from ALL moving parts of door.
• NEVER permit children to operate or play with door control
push buttons or remote controls.
• Activate door ONLY when it can be seen clearly, is properly
adjusted and there are no obstructions to door travel.
• ALWAYS keep door in sight until completely closed. NEVER
permit anyone to cross path of closing door.

1. Remove the control station cover.
2. Fasten the control station to the wall at least 5 feet (1.5 m)
above the ground. The installation surface must be smooth
and flat.
3. Select appropriate knockout and run the wires to the operator.
4. Connect wires to the control station and replace the control
station cover.
5. Fasten the warning placards to the wall.

Factory installed
jumper must be in
place for proper
operation. Operator
will not function
without the jumper.

DO NOT EXCEED 10 DOOR OPERATIONS
PER HOUR.
FASTEN LABEL ADJACENT TO DOOR.
NE PAS FAIRE FONCTIONNER LA PORTE
PLUS DE 10 FOIS PAR HEURE.
FIXER L’ÉTIQUETTE PRÈS DE LA
PORTE.
132A2112-2

WHT/RED

WARNING

WHT
Door Control
Connections

Moving Door Can Cause
Serious Injury or Death

Single Button Control Station

Keep Clear! Door May Move at any Time
Without Prior Warning
Do Not Let Children Operate the Door or Play
in the Door Area
Keep Door in Sight at all Times When Door is Moving

INSTALLATION STEP 5
Electrical Requirements

To prevent possible SERIOUS INJURY or DEATH from
electrocution or fire:
• Be sure power is not connected to the operator, and
disconnect power to circuit BEFORE removing cover to
establish permanent wiring connection.
• Door installation and wiring MUST be in compliance with
ALL local electrical and building codes.
• NEVER use an extension cord, 2-wire adapter or change
plug in ANY way to make it fit outlet. Be sure the operator is
grounded.

To avoid installation difficulties, do not run the operator at this
time.
To reduce the risk of electric shock, your operator has a
grounding type plug with a third grounding pin. This plug will
only fit into a grounding type outlet. If the plug doesn’t fit into
the outlet you have, contact a qualified electrician to install the
proper outlet.

PERMANENT WIRING CONNECTION
RIGHT

WRONG

Flexible Conduit

Green
Ground
Screw

If permanent wiring is required by your local code, refer to the
following procedure.
To make a permanent connection through the 7/8" hole in the
back of the operator (according to local code):
1. Remove cover screws and set the cover aside.
2. Remove the attached green ground terminal.
3. Cut black and white wires and strip away 1/2" (1.3 cm) of
insulation, 3" (7.6 cm) before spade terminals.
4. Remove the power cord from unit.
5. Install a 90º conduit or flex cable adapter to the 7/8" hole.
6. Run wires through conduit, cut to proper length and strip
insulation.
7. Attach with wire nuts.
8. Properly secure wire under plastic ties so that wire does not
come in contact with moving parts.
9. Reinstall the cover.
To avoid installation difficulties, do not run the operator at this
time.

Ground Tab

Ground Wire

Black Wire
From Power Cord
White Wire
From Power Cord

PERMANENT WIRING CONNECTION

Black Wire
Green Wire

90˚ Connector

White Wire

INSTALLATION STEP 6
Install The Protector System®

Be sure power is not connected to the door operator BEFORE
installing the safety reversing sensor.
To prevent SERIOUS INJURY or DEATH from a closing door:
• Correctly connect and align the safety reversing sensor.
This required safety device MUST NOT be disabled.
• Install the safety reversing sensor so beam is NO HIGHER
than 6" (15 cm) above floor.

The safety reversing sensor must be connected and aligned
correctly before the door operator will move in the down
direction. This is a required safety device and cannot be
disabled.
IMPORTANT INFORMATION ABOUT THE SAFETY REVERSING
SENSOR
When properly connected and aligned, the safety reversing sensor
will detect an obstacle in the path of its electronic beam. The
sending eye (with an amber indicator light) transmits an invisible
light beam to the receiving eye (with a green indicator light). If an
obstruction breaks the light beam while the door is closing, the
door will stop and reverse to full open position.
The units must be installed inside the building so that the sending
and receiving eyes face each other across the door, no more than
6" (15 cm) above the floor. Either can be installed on the left or
right of the door as long as the sun never shines directly into the
receiving eye lens.

Safety Reversing Sensor
6" (15 cm) max. above floor

If it is necessary to mount the units on the wall, the brackets
must be securely fastened to a solid surface such as the wall
framing. Extension brackets (see accessories) are available if
needed. If installing in masonry construction, add a piece of wood
at each location to avoid drilling extra holes in masonry if
repositioning is necessary.
The invisible light beam path must be unobstructed. No part of
the door (door tracks, springs, hinges, rollers or other hardware)
may interrupt the beam while the door is closing.

Safety Reversing Sensor
6" (15 cm) max. above floor

Invisible Light Beam
Protection Area

Facing the door from inside.

INSTALLING THE BRACKETS
Be sure power to the operator is disconnected. Install and align
the brackets so the safety reversing sensors will face each other
across the door, with the beam no higher than 6" (15 cm) above
the floor. They may be installed in one of three ways, as follows.
Wall installation (Figures 1 and 2):
• Place the bracket against the wall with curved arms facing the
door. Be sure there is enough clearance for the sensor beam to
be unobstructed.
• If additional depth is needed, an extension bracket
(see accessories) or wood blocks can be used.
• Use bracket mounting holes as a template to locate and drill
(2) 3/16" diameter pilot holes on the wall at each side of the
door, no higher than 6" (15 cm) above the floor.
• Attach brackets to wall with lag screws (Not provided).
• If using extension brackets or wood blocks, adjust right and
left assemblies to the same distance out from the mounting
surface. Make sure all door hardware obstructions are cleared.
Floor installation (Figure 3):
• Use wood blocks or extension brackets (see accessories) to
elevate sensor brackets so the lenses will be no higher than
6" (15 cm) above the floor.
• Carefully measure and place right and left assemblies at the
same distance out from the wall. Be sure all door hardware
obstructions are cleared.
• Fasten to the floor with concrete anchors as shown.

Figure 1

WALL MOUNT (RIGHT SIDE)

ide
Ins l
l
a
W

Fasten Wood Block to Wall with
Lag Screws (Not Provided)
Indicator
Light

Sensor
Bracket

Lag Screws
(Not Provided)
Lens

Figure 2

WALL MOUNT (RIGHT SIDE)
ide
Ins l
l
Wa

Extension Bracket
(See Accessories)
(Provided with
Extension Bracket)

Sensor
Bracket

(Provided with
Extension
Bracket)
Lens

Figure 3

Indicator
Light

FLOOR MOUNT (RIGHT SIDE)

ide
Ins ll
a
W

Attach with
Concrete Anchors
(Not Provided)
Lens
Indicator
Light
Sensor
Bracket

MOUNTING AND WIRING THE SAFETY REVERSING SENSORS
• Slide a 1/4"-20x1/2" carriage bolt head into the slot on each
sensor. Use wing nuts to fasten safety reversing sensors to
brackets, with lenses pointing toward each other across the
door. Be sure the lens is not obstructed by a bracket extension
(Figure 4).
• Finger tighten the wing nuts.
• Run the wires from both safety reversing sensors to the
operator. Use insulated staples to secure wire to wall and
ceiling.
• Strip 7/16" (11 mm) of insulation from each set of wires.
Separate white and white/black wires sufficiently to connect to
the operator quick-connect terminals: white to white and
white/black to grey (Figure 5).
ALIGNING THE SAFETY REVERSING SENSORS
• Plug in the operator. The indicator lights in both the sending
and receiving eyes will glow steadily if wiring connections and
alignment are correct.
The sending eye amber indicator light will glow regardless of
alignment or obstruction. If the green indicator light in the
receiving eye is off, dim, or flickering (and the invisible light beam
path is not obstructed), alignment is required.
• Loosen the sending eye wing nut and readjust, aiming directly
at the receiving eye. Lock in place.
• Loosen the receiving eye wing nut and adjust the safety
reversing sensor until it receives the sender’s beam. When the
green indicator light glows steadily, tighten the wing nut.

Figure 4
Wing Nut
1/4"-20

Carriage Bolt
1/4"-20x1/2"

Lens

TROUBLESHOOTING THE SAFETY REVERSING SENSORS
1. If the sending eye indicator light does not glow steadily after
installation, check for:
• Electric power to the operator.
• A short in the white or white/black wires. These can occur at
staples, or at operator connections.
• Incorrect wiring between safety reversing sensors and
operator.
• A broken wire.
2. If the sending eye indicator light glows steadily but the
receiving eye indicator light doesn’t:
• Check alignment.
• Check for an open wire to the receiving eye.
3. If the receiving eye indicator light is dim, realign either sensor.
NOTE: When the invisible beam path is obstructed or misaligned
while the door is closing, the door will reverse. If the door is
already open, it will not close.

Bell Wire

Motor unit

Figure 5

Bell Wire

Sensor
Connections
WHT/BLK
WHT
Quick-Connect Terminals
To insert or release wires, push
in tab with screwdriver tip.

Safety Reversing Sensor

Invisible Light Beam
Protection Area

ADJUSTMENT STEP 1
Program the Travel Limits
Without a properly installed safety reversal system, persons
(particularly small children) could be SERIOUSLY INJURED or
KILLED by a closing door.
• NEVER learn forces or limits when door is binding or
sticking. Repair door first.
• Incorrect adjustment of door travel limits will interfere with
proper operation of safety reversal system.
• After ANY adjustments are made, the safety reversal system
MUST be tested.

Travel limits regulate the points at which the door will stop
when moving up or down.
Adjust the position of the door by using the black and purple
buttons. Black moves the door UP (open) and purple moves the
door DOWN (close).
NOTE: The safety reversing sensors MUST be installed to
program the limits.
Figure 1

LED

Black
Button

To prevent damage to vehicles, be sure fully open door
provides adequate clearance.

Purple
Button

Figure 1

Setting the UP position:
1. Press and hold the black button until the LED starts flashing
slowly, then release.
2. Push and hold the black button until the door reaches the
desired UP (open) position.
NOTE: Make sure the door opens high enough for your vehicle.
3. Push the door control. This sets the UP (open) limit and begins
closing the door.
4. Immediately when the door begins to close, press and release
either the black or purple button. This will stop the door.
Setting the DOWN position:
5. Push and hold the purple button until the door reaches the
desired DOWN (closed) position.
6. Once the door is closed, if there appears to be too much
pressure on the door, you may toggle the door back and forth
using the black and purple buttons to reach the desired closed
position.
7. Push the door control. This sets the DOWN (close) limit and the
door should open.
Proceed to Set the Force.

Figure 2

BLACK

PURPLE

Figure 3

Figure 4

BLACK

PURPLE

Figure 5

Figure 7

Figure 6

BLACK

PURPLE

ADJUSTMENT STEP 2
Set the Force
Without a properly installed safety reversal system, persons
(particularly small children) could be SERIOUSLY INJURED or
KILLED by a closing door.
• NEVER learn forces or limits when door is binding or
sticking. Repair door first.
• Too much force on door will interfere with proper operation
of safety reversal system.
• After ANY adjustments are made, the safety reversal system
MUST be tested.

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 remote control or door control. The door will close
(DOWN).
3. Push the remote control or door control again. The door will
open (UP).
4. Push the remote control or door 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.

Figure 1

LED

Black
Button

Figure 2
BLACK

Push Purple button
twice to enter
unit into Force
Adjustment Mode
PURPLE

Purple
Button

Figure 3

ADJUSTMENT STEP 3
Test The Protector System®
Without a properly installed safety reversing sensor, persons
(particularly small children) could be SERIOUSLY INJURED or
KILLED by a closing door.

• Press the single button control station to open the door.
• Place the operator carton in the path of the door.
• Press the single button control station to close the door. The
door will not move more than an inch, and the operator lights
will flash.
The door operator will not close if the indicator light in either
sensor is off (alerting you to the fact that the sensor is misaligned
or obstructed).
If the operator closes the door when the safety reversing sensor
is obstructed, do not operate the door. Call for a trained door
systems technician.

Safety Reversing Sensor

ADJUSTMENT STEP 4
To Open the Door Manually

• The door should be fully closed if possible.
• Pull the emergency release handle until the latch engages
(a click noise can be heard). The door should then be able to
be opened manually.
• Return the door to the closed position.
• Pull the emergency handle a second time until the latch
releases.
• The door will reconnect on the next open or close operation.
NOTE: To prevent damage to the motor assembly, NEVER use the
emergency release to toggle or stop a falling door. ONLY use the
emergency release to manually open or close the door.

WARNING
Door may fall
when released.
NEVER use
emergency
release to stop
a falling door.
If possible,
ONLY use the
emergency
release when
door is closed.
For
For manual
manual
operation
operation
pull cord down
pull cord down

NOT
ICE

WARNING
OPERATION

IMPORTANT SAFETY INSTRUCTIONS
WARNING
To reduce the risk of SEVERE INJURY or DEATH:
1. READ AND FOLLOW ALL WARNINGS AND INSTRUCTIONS.
2. ALWAYS keep remote controls out of reach of children.
NEVER permit children to operate or play with door control
push buttons or remote controls.
3. ONLY activate door when it can be seen clearly, it is
properly adjusted and there are no obstructions to door
travel.
4. ALWAYS keep door in sight until completely closed. NO
ONE SHOULD CROSS THE PATH OF THE MOVING DOOR.
5. NO ONE SHOULD GO UNDER A STOPPED, PARTIALLY
OPENED DOOR.
6. If possible, use emergency release handle to disengage door
ONLY when door is CLOSED. Weak or broken springs or
unbalanced door could result in an open door falling rapidly
and/or unexpectedly, causing SEVERE INJURY or DEATH.
7. NEVER use emergency release handle unless doorway is
clear of persons and obstructions.

8. After ANY adjustments are made, the safety reversal
system MUST be tested.
9. Safety reversal system MUST be tested every month. Door
MUST reverse on contact with 1-1/2" (3.8 cm) high object
(or a 2x4 laid flat) on the floor. Failure to adjust the garage
door opener properly may cause SEVERE INJURY or
DEATH.
10. ALWAYS KEEP DOOR PROPERLY BALANCED (see
page 3). An improperly balanced door may not reverse
when required and could result in SEVERE INJURY or
DEATH.
11. ALL repairs to cables, spring assemblies and other
hardware, ALL of which are under EXTREME tension,
MUST be made by a trained door systems technician.
12. ALWAYS disconnect electric power to garage door opener
BEFORE making ANY repairs or removing covers.
13.

SAVE THESE INSTRUCTIONS.

Using Your Operator

Care of Your Operator

Press and hold the push button on the single button control
station until the door starts to move.
When the operator is activated (with the safety reversing
sensor correctly installed and aligned)
1. If open, the door will close. If closed, it will open.
2. If closing, the door will reverse.
3. If opening, the door will stop.
4. If the door has been stopped in a partially open position,
it will close.
5. If an obstruction interrupts the sensor beam while closing the
operator will reverse.
6. The sensor has no effect in the opening cycle.
7. If fully open, the door will not close when the beam is broken.

MAINTENANCE SCHEDULE
Once a Month
• Manually operate door. If it is unbalanced or binding, call a
trained door systems technician.
• Check to be sure door opens & closes fully. Adjust limits
and/or force if necessary (see Adjustment Steps 1 and 2).
• The operator does not require additional lubrication.
Do not grease the door tracks.

HAVING A PROBLEM?
(TROUBLESHOOTING)
1. The operator doesn’t operate from either the door control or
the remote control:
• Does the operator have electric power? Plug a lamp into the
outlet. If it doesn’t light, check the fuse box or the circuit
breaker. (Some outlets are controlled by a wall switch.)
• Is there a build-up of ice or snow under the door? The door
may be frozen to the ground. Remove any restriction.
• The door spring may be broken. Have it replaced (see page 3
for reference).
2. Operator operates from the remote, but not from the single
button control station:
• Are the wiring connections correct? Review Installation
Step 4.
3. The door operates from the single button control station,
but not from the remote control:
• Program the operator to match the remote control code.
(Refer to instructions on the motor unit panel.) Repeat with
all remotes.
4. The remote control has short range:
• Check to be sure the antenna on the side or back panel of
operator extends fully downward.
• Some installations may have shorter range due to a metal
door, foil backed insulation, or metal siding.
5. The door opens and closes by itself:
• Be sure that all remote control push buttons are off.
• Remove the bell wire from the door control terminals and
operate from the remote only. If this solves the problem, the
single button control station is faulty (replace), or there is an
intermittent short on the wire between the control console
and the motor unit.
• Clear memory and re-program all remote controls.
6. The door doesn’t open completely:
• Is something obstructing the door? Is it out of balance, or
are the springs broken? Remove the obstruction or repair
the door.
7. The door opens but won’t close:
• Check the safety reversing sensor. See Installation Step 6.
• See Adjustment Step 2. For an existing installation,
see below.
Repeat the safety reverse test after the adjustment is complete.

8. The door reverses for no apparent reason:
• Is something obstructing the door? Pull the emergency
release handle. Operate the door manually. If it is
unbalanced or binding, call a trained door systems
technician.
• Clear any ice or snow from the floor area where the door
closes.
• Review Adjustment Step 2.
Repeat safety reverse test after adjustments.
9. The door reverses for no apparent reason:
• Check the safety reversing sensor. Remove any obstruction
or align the receiving eye. See Installation Step 6.
10. The operator strains to operate door:
• The door may be out of balance or the springs may be
broken. Close the door and use the emergency release
handle to disconnect the door. Open and close the door
manually. A properly balanced door will stay in any point of
travel while being supported entirely by its springs. If it
does not, disconnect the operator and call a trained door
systems technician.
11. The operator motor hums briefly, then won’t work:
• The door springs may be broken. See above.
12. The operator won’t operate due to power failure:
• Use the emergency release handle to disconnect the door.
The door can be opened and closed manually. When power
is restored, pull manual release a second time.
• If a standby power unit is connected, the operator should
be able to operate up to 20 times without power.
13. Door loses limits:
• Reprogram limits see Adjustment Step 1.
14. The operator moves when the door is in operation:
• Minor movement for this operator is normal as long as it is
not excessive.
• Check all mounting hardware to the operator and/or
operator mounting brackets. Verify the operator is
mounted at a right angle to the door shaft, sprocket and
chain are aligned.

Motor unit

Installed
Safety Reversing
Sensor
“Learn”
Button LED
or Diagnostic
LED
“Learn”
Button

Your door operator is programmed with self-diagnostic capabilities.
The “Learn” button/diagnostic LED will flash a number of times then
pause signifying it has found a potential issue. Consult Diagnostic
Chart below.

Diagnostic Chart

1 FLASH
Safety reversing sensors
wire open (broken or
disconnected).

2 FLASHES
Safety reversing sensors
wire shorted or black/white
wire reversed.

3 FLASHES
Door control or
wire shorted.

4 FLASHES
Safety reversing sensors
slightly misaligned
(dim or flashing LED).

5 FLASHES
Motor overheated or
possible RPM sensor
failure. Unplug to reset.

9 FLASHES
Factory installed jumper
loose or missing.

Symptom: One or both of the Indicator lights on the safety reversing sensors do not glow
steady.
• Inspect sensor wires for a short (staple in wire), correct wiring polarity (black/white wires
reversed), broken or disconnected wires, replace/attach as needed.
• Disconnect all wires from back of motor unit.
• Remove sensors from brackets and shorten sensor wires to 1-2 feet (30-60 cm) from back
each of sensor.
• Reattach sending eye to motor unit using shortened wires. If sending eye indicator light glows
steadily, attach the receiving eye.
• Align sensors, if the indicator lights glow replace the wires for the sensors. If the sensor
indicator lights do not light, replace the safety reversing sensors.
Symptom: The door doesn’t activate from the door control.
• Inspect door control/wires for a short (staple in wire), replace as needed.
• Disconnect wires at door control, touch wires together. If motor unit activates, replace door
control.
• If motor unit does not activate, disconnect door control wires from motor unit. Momentarily
short across red and white terminals with jumper wire. If motor unit activates, replace door
control wires.
Symptom: Sending indicator light glows steadily, receiving indicator light is dim
or flashing.
• Realign receiving eye sensor, clean lens and secure brackets.

Symptom: Door travels 2-3 inches and stops.
• Reprogram limits and forces. See Adjustments section.
• If the operator continues to travel 2-3 inches, check the travel module connection or replace
the travel module.
Symptom: Door travels 2-3 inches and stops.
• Reengage the emergency release.
• Motor may need to be replaced.
Symptom: Door reverses while closing.
• Check the factory installed jumper at the terminal connections. Factory installed jumper must
be in place for proper operation. Operator will not function without the jumper.

PROGRAMMING
NOTICE: If this Security✚® door operator is operated with a non-rolling code transmitter, the technical measure in the receiver of the
door operator, which provides security against code-theft devices, will be circumvented. The owner of the copyright in the door
operator does not authorize the purchaser or supplier of the non-rolling code transmitter to circumvent that technical measure.

To Add or Program a Hand-held Remote Control (Not Provided)
Below are instructions for programming your operator to operate with optional Security✚® remote controls. A maximum of eight
Security✚® remote controls can be programmed to work with your operator.
1. Press and release the purple “learn”
button on the motor unit. The learn
indicator light will glow steadily for 30
seconds.

USING THE “LEARN” BUTTON

2. Within 30 seconds, press and hold the
button on the hand-held remote* that
you wish to operate your door.

3. Release the button when the learn
indicator light blinks and shuts off upon
learning the remote control. If the
optional remote light is installed, the
light will blink.
4. If the safety reversing sensors are not installed or misaligned,
the door will not close from a hand-held remote control. If this
occurs, the door can be closed by pressing and holding the
push button on the single button control station until the door
has closed. Releasing the push button prior to the door closing
will cause the door to reverse.

To Erase All Codes From Motor Unit Memory
To deactivate any unwanted remote, first erase all codes:
Press and hold the “learn” button on motor
unit until the learn indicator light goes out
(approximately 6-9 seconds).
All previous codes are now erased.
Reprogram each remote or keyless entry you
wish to use.

To Add, Program or Change a Keyless Entry PIN (Not Provided)
NOTE: The optional Keyless Entry must be programmed to operate your door operator.
USING THE “LEARN” BUTTON
Optional

To change an existing, known PIN
If the existing PIN is known, it may be changed by one person
without using a ladder.
1. Press the four buttons for the present PIN, then press and hold
the # button.
The operator light will blink twice. Release the # button.
2. Press the new 4-digit PIN you have chosen, then press Enter.
The motor unit lights will blink once when the PIN has
been learned.
Test by pressing the new PIN, then press Enter. The door
should move.
To set a temporary PIN
You may authorize access by visitors or service people with
a temporary 4-digit PIN. After a programmed number of hours or
number of accesses, this temporary PIN expires and will no
longer open the door. It can be used to close the door even after it
has expired. To set a temporary PIN:
1. Press the four buttons for your personal entry PIN (not the last
temporary PIN), then press and hold the button.
The operator light will blink three times. Release the button.
2. Press the temporary 4-digit PIN you have chosen, then
press Enter.
3. To set the number of hours this temporary PIN will work, press
the number of hours (up to 255), then press ✽.
NOTE: If the optional remote light is installed, the remote light will
blink 4 times.

1. Press and release the purple “learn”
button on motor unit. The learn indicator
light will glow steadily for 30 seconds.

2. Within 30 seconds, enter a four digit
personal identification number (PIN) of
your choice on the keypad. Then press
and hold the ENTER button.
3. Release the button when the learn
indicator light blinks and shuts off upon
learning the remote control. If the
optional remote light is installed, the light
will blink.

REPAIR PARTS
Installation Parts

10
1
2

9
5

NOT
ICE

KEY
NO.
1
2

PART
NO.
APBS 1
41A6298-5

3
4
5

41B4494-1
41C0902
41A5034

7
KEY
NO.
6
7
8
9
10

DESCRIPTION
Single button control station
Emergency release rope, handle assembly
and installation hardware bag
(includes hardware listed on page 4)
2-conductor bell wire white & white/red
Mounting bracket (1)
Safety reversing sensor kit (receiving and
sending eyes) with 3 feet (.9 m)
2-conductor bell wire attached

PART
NO.
41A5266-1
41A7279
41A7280
41A7278
41A7314
114A4066

8
DESCRIPTION
Safety reversing sensor brackets (2)
Live shaft sprocket kit
Dead shaft sprocket kit
12 tooth sprocket kit
Drive chain (#48)
NOT SHOWN
Owner’s manual

Motor Unit Assembly Parts

5
2
1

KEY
NO.
1
2
3

PART
NO.
DESCRIPTION
K41DJC001 Logic board complete with plate (315 MHz)
41A6408 Travel Module
41C168
Transformer

KEY
NO.
4
5

PART
NO.
DESCRIPTION
41A6095 Motor with bracket
41A6348-3 Cover

ACCESSORIES
41A5281

Extension Brackets:
(Optional) For safety reversing sensor
installation onto the wall or floor.

377LM

Keyless Entry with Security✚® :
Enables end user to operate door
operator from outside by entering a
password on a specially designed
keyboard. Also can add a temporary
password for visitors or service
persons. This temporary password
can be limited to a programmable
number of hours or entries.

380LM

475LM

EverCharge® Standby Power System:
Provides backup power to the model
3900 door operator.

41A6102

Power Door Lock:
Enables the end user to prevent the door
from being manually opened once closed.

Remote Work Light:
Enables homeowner to turn on a work
light from their car with their door
operator remote or from anywhere in
their home with an additional LiftMaster
Security✚® remote.

3950MB

Guide Mounting Bracket Kit:
The bracket can be mounted in several
different configurations with the motor
location outside or inside the door guides.

371LM

1-Button Security✚®
Remote Control :
Includes visor clip.

3950CGJ

Chain Guard:
The chain guard is required to comply
with UL requirements for applications
where the drive chain is exposed lower
than 8 feet (2.5 m).

372LM

2-Button Security✚®
Remote Control :
Includes visor clip.

373LM

3-Button Security✚®
Remote Control :
Includes visor clip.

NOTES

LIFTMASTER® SERVICE
IS ON CALL

HOW TO ORDER
REPAIR PARTS

OUR LARGE SERVICE ORGANIZATION
SPANS AMERICA

Selling prices will be furnished on request or parts will be shipped at
prevailing prices and you will be billed accordingly.

INSTALLATION AND SERVICE INFORMATION
IS AS NEAR AS YOUR TELEPHONE.

WHEN ORDERING REPAIR PARTS,
ALWAYS GIVE THE FOLLOWING INFORMATION:

SIMPLY DIAL OUR TOLL FREE NUMBER:

• PART NAME
• MODEL NUMBER

1-800-528-2806

ADDRESS ORDERS TO:
THE CHAMBERLAIN GROUP, INC.
Technical Support Group
6050 S. Country Club Road
Tucson, Arizona 85706

www.liftmaster.com

For professional installation, parts and service, contact your local
LIFTMASTER/CHAMBERLAIN dealer. Look for him in the Yellow
Pages, or call our Service number for a list of dealers in your area.

114A4066D

• PART NUMBER

SERVICE INFORMATION
TOLL FREE NUMBER:

1-800-528-2806

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Liftmaster 3950 Owners Manual 114A4066C

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