Craftsman 139.53491SRT User manual

1/2 HP
GARAGE DOOR OPENER
OWNER’S
MANUAL
Model No.
139.53491SRT
For Residential Use
Only
Caution:
Read and follow all
safety rules and
operating instructions
before first use of this
product.
Fasten the manual
near the garage door
after installation.
The Chamberlain Group, Inc.
Liftmaster Model Screw Drive
# 114A1794
Cover Illustration
5/3/94 - 6/14/94 - 10/18/94
Complies with UL 325
regulations effective
January 1, 1993
®®®®
■Safety Precautions
■Assembly
■Installation
■Adjustment
■Care and Maintenance
■Operation
■Troubleshooting
■Parts List
®
Sears, Roebuck and Co., Hoffman Estates, IL 60179 U.S.A.

Start by reviewing these important safety alert symbols:
2
Safety alert symbol review............................................2
Safety information, precautions, tools..........................3
Testing your garage door for binding & balance..........3
Carton inventory ...........................................................4
Hardware inventory.......................................................5
Illustration of sectional door installation .....................6
Illustration of one-piece door installation.....................7
Assembly section - pages 8 – 11
Assemble the rail ........................................................8
Fasten rail to power unit............................................10
Install the trolley.......................................................10
Attach the rail brackets .............................................11
Installation section - pages 12 – 27
Installation safety instructions ..................................11
Determine the header bracket location
Sectional door .........................................................12
One-piece door........................................................13
Install the header bracket..........................................14
Attach the rail to the header bracket.........................15
Safety reversing sensor information .........................16
Install the safety reversing sensor.............................17
Position the opener....................................................19
Hang the opener........................................................20
Install the door control and connect all wires...........21
Electrical requirements .............................................22
Complete the safety reversing sensor installation.....22
Install the lights and lens ..........................................23
Attach the emergency release rope and handle.........23
Fasten the door bracket (sectional door)...................24
Fasten the door bracket (one-piece door)..................25
Connect door arm to trolley (sectional door)............26
Connect door arm to trolley (one-piece door)...........27
Adjustment section - pages 28 – 30
Travel limit adjustments............................................28
Force adjustments .....................................................29
Test the safety reversing sensor ................................30
Test the safety reverse system ..................................30
Operation safety instructions ......................................31
Care of your opener ....................................................31
Maintenance schedule.................................................31
Operation of your opener............................................32
Receiver & remote control programming...................33
Troubleshooting..........................................................34
Repair parts, rail assembly..........................................36
Repair parts, installation .............................................36
Repair parts, power unit..............................................37
Accessories .................................................................38
Index ...........................................................................39
How to order repair parts............................................40
Warranty......................................................................40
When you see these Safety Symbols on the following pages, they will alert you to the possibility of
serious injury
or death if you do not comply with the corresponding instructions. The hazard may come from something
mechanical or from electric shock. Read the instructions carefully.
When you see this Safety Symbol on the following pages, it will alert you to the possibility of damage to your
garage door and/or the garage door opener if you do not comply with the corresponding instructions. Read the
instructions carefully.
This garage door opener is designed and tested to offer safe service provided it is installed, operated, maintained
and tested in strict accordance with the safety instructions contained in this manual.
Mechanical
Electrical
WARNING
CAUTION
WARNING
WARNING
WARNING
CAUTION
WARNING
WARNING
WARNING
CAUTION
WARNING
WARNING
Contents

3
The Chamberlain Group, Inc.
Testing Force Setting
New GDO Manual
2/1/92
Sectional Door
One-Piece Door
The Chamberlain Group, Inc.
Testing Force Setting
New GDO Manual
2/1/92
Pliers
Wire Cutters
Claw Hammer
Hack Saw
Screwdriver
1/2" & 7/16" Sockets
and Wrench
Drill
Tape Measure
1/2" x 7/16" Box Wrench
2
1
Stepladder
Pencil
3/16", 5/16" and
5/32" Drill Bits
Carpenter's
Level
The Chamberlain Group, Inc.
Tools
10/19/94
During assembly, installation and adjustment of the opener, instructions will call for tools shown below.
An unbalanced garage door might not re verse when
required and someone under the door could be seriously
injured or killed.
If your garage door binds, sticks or is out of balance, call
for professional garage door service. Garage doors, door
springs, cables, pulleys, brackets, and their hardware are
under extreme tension and can cause serious injur y or
death. Do not try to loosen, mo ve or adjust them
yourself!
Ropes left on a garage door could cause someone to
become entangled and killed. Remove all ropes
connected to the door before installing and operating the
opener.
To avoid damage to the garage door and opener, disable
locks before installing and operating the opener. Use a
wood screw or nail to hold locks in the "open" (unlocked)
position.
Operation at other than 120V 60 Hz will cause opener
malfunction and damage.
WARNING
CAUTION
WARNING
WARNING
WARNING
CAUTION
WARNING
WARNING
Identify the type and height of your door, any special
conditions that exist, and any additional materials that
may be required. Refer to pages 6 and 7.
Test Your Door for Balance
Before you begin, complete the following test to make
sure your door is balanced, and is not sticking or
binding:
• Lift the door about halfway as shown. Release the door.
It should stay in place, supported entirely by its springs.
• Raise and lower the door to see if there is any binding or
sticking.
Safety Information and Precautions; Tools

4
Straight Door
Arm Section
Door Bracket Plate Door Bracket
Curved Door
Arm Section
Header/Rail
Brackets
Rail Support
Braces (4)
Header Bracket
UP
CEILING MOUNT ONLY
Safety Reversing Sensor
Mounting Bracket
With Square Holes (2) "C" Wrap (2)
Safety Reversing Sensor
Mounting Bracket
With Slot (2)
Sprocket
Coupling
2-Conductor Bell Wire
White & White/Red
Rail
Assembly
Light Lens
Trolley
Hanging Brackets
Safety Labels
and
Literature
(2) Safety Reversing Sensors 
(1 Sending Eye and 1 Receiving Eye)
with attached
2-Conductor White & White/Black Bell Wire
Three-Function Remote Control
with Visor Clip (2)
Standard 
Control Console
Carton Inventory
Your garage door opener is packaged in one carton which contains the power unit and all parts illustrated below. If anything
is missing, carefully check the packing material. Parts may be "stuck" in the foam.
KEEP THE FOAM INTACT (see page
10). Hardware for assembly and installation is shown on page 5.

Hardware
5
Separate all hardware from the packages in the rail carton and the opener carton and group as shown below, for
the assembly and installation procedures.
Lock Nut
1/4"-20 x 7/16 (12)
7
Lock Nut
1/4"-20 x 7/16 (4)
Carriage Bolt
1/4"-20x1/2" (4)
Safety Reversing Sensor Installation Hardware
Hex Screw
1/4-20x1-1/2" (2) Screw
#10-32x3/8" (4) Lock Nut
#10x32 (4)
Wing Nut (2)
Insulated
Staples (20)
Lag Screw
1/4x1-1/2" (4)
1/4" - 20 x 5/8"
Hex Screw (4) Sprocket Coupling Sleeve
Assembly Hardware
Bolt
1/4-20x1-3/4" (8)
Installation Hardware
NOTICE
Handle
Nut 5/16"-18 (6)
Ring 
Fastener (3)
Clevis Pin
5/16"x2-3/4" (1)
Insulated
Staples (10)
Dry Wall Anchors (2)
Clevis Pin
5/16"x1" (1)
Hex Screw
5/16"-18x7/8" (4)
Rope
Carriage Bolt
5/16"-18x2-1/2" (2)
Screw
6ABx1" (2)
Lock Washer 5/16" (6)
Lag Screw
5/16"-9x1-5/8" (2)
Clevis Pin
5/16"x1-1/4" (1)
Lag Screw
5/16"-18x1-7/8" (2)

6
Safety Reversing Sensor
Horizontal and vertical reinforcement
is needed for lightweight garage doors
(fiberglass, steel, aluminum, door with glass panels, etc.).
See page 24 for details.
Support bracket &
fastening hardware
is required.
See page 20.
— — — — — — — —
Door Center
Header Wall
Safety
Reversing
Sensor
Floor must be level
across width of door
FINISHED CEILING
Extension Spring
Torsion Spring
Access Door
OR
Header
Bracket Rail
Bracket
Trolley
Straight
Door
Arm
Emergency
Release
Rope & Handle
Door
Bracket
Garage
Door
Curved
Door
Arm
Garage
Door
Spring
Header
Wall
Rail Assembly
Closed Position
SECTIONAL Door Installation
Before you begin, survey your garage area to
see whether any of the conditions below apply
to your installation.
Based on your particular requirements, there are several
installation steps which might call for materials and/or
hardware not included in the carton.
• Step 1, page 12 – Look at the wall or ceiling above the
garage door. The header bracket
must be securely
fastened to structural supports.
• Safety reversing sensor, page 16 – Depending upon
garage construction, wood blocks may need to be
fastened to mounting locations before sensors are
installed.
• Step 4, page 17 – Alternate floor mounting of the safety
reversing sensor will require hardware not provided.
• Step 6, page 20 – Do you have a finished ceiling in your
garage? If so, a support bracket and additional fastening
hardware may be required.
• Step 12, page 24 – Do you have a steel, aluminum,
fiberglass or glass panel door? If so, horizontal and
vertical reinforcement is required.
• Look at the garage door where it meets the floor. It
must close on the floor all the way across. Otherwise,
the safety reverse system may not work properly. See
page 30. Floor or door should be repaired.
• The opener can be installed within 2 feet of the left or
right of the door center if there is a torsion spring or
center bearing plate in the way of the header bracket or
door bracket area. If your door has extension springs,
the opener must be installed in the center of the door.
See pages 12 and 24.
• Do you have an access door in addition to the garage
door? If not, Model 53702 Emergency Key Release is
required. See page 38.
You may find it helpful to refer back to this page as
you proceed with the installation of your opener.

7
Safety Reversing Sensor
FINISHED CEILING
Support bracket
& fastening
hardware is required.
See page 20.
Safety Reversing
Sensor
Header
Wall
Access Door
The Chamberlain Group, Inc.
Completed Installation - One-Piece
Liftmaster Screw Drive #114A1794
6/5/94
Gap between floor and bottom of
door must not exceed 1/4".
Closed Position
Header
Bracket Trolley
Straight
Door
Arm
Emergency
Release
Rope & Handle
Door
Bracket
Curved
Door
Arm
Header
Wall
Rail Assembly
Garage
Door
Rail
Bracket
Before you begin, survey your garage area to
see whether any of the conditions below apply
to your installation.
Based on your particular requirements, there are several
installation steps which might call for materials and/or
hardware not included in the carton.
• Step 1, page 13 – Look at the wall or ceiling above the
garage door. The header bracket must be securely
fastened to structural supports.
• Step 6, page 20 – Do you have a finished ceiling in your
garage? If so, a support bracket and additional fastening
hardware (not supplied) may be required.
• Safety reversing sensor, page 16 – Depending on garage
construction, wood blocks may need to be securely
fastened to mounting locations before sensors are
installed.
• Step 14, page 17 – Alternate floor mounting of the
safety reversing sensor will require hardware that is not
provided.
• Step 12, page 25 – Generally, a one-piece door does not
require reinforcement. If your door is lightweight, you
can refer to the information relating to sectional doors
on page 24.
• Step 12, page 25 – Depending on your door's
construction, you might need additional mounting
hardware for the door bracket.
• Do you have an access door in addition to the garage
door? If not, Model 53702 Emergency Key Release is
required. See page 38.
• The gap between the bottom of the garage door and
the floor cannot exceed 1/4". Otherwise, the safety
reverse system may not work properly. See page 30.
The floor or the door should be repaired.
ONE-PIECE Door Installation
You may find it helpful to refer back to this page as
you proceed with the installation of your opener.
One-Piece Door without Track
Access
Door
Floor must be level
across width of door
Safety
Reversing Sensor
The Chamberlain Group, Inc.
One-Piece Door with Track Installation (Cable -USA)
3/3/93
Header
Bracket
Door
Bracket Straight
Door
Arm
Curved
Door Arm
Trolley
Emergency Release
Rope & Handle
Rail Assembly
Garage
Door
Header
Wall
Safety
Reversing
Sensor
One-Piece Door With Track
Closed Position
Rail
Bracket

8
The Chamberlain Group, Inc.
Screw Drive LM 
3-Piece Rail
Unpacking Carton and Extending End Rails 
7/30/94 - 8/4/94 - 1/11/95
Center
Rail
Trolley Rack
Extend
End Rails 
Outward
Extend 
End Rails 
Outward
Rail Assembly
Carton
Remove
Cardboard Packing
Remove
Cardboard Packing
Rail 
Support 
Braces
Straight
Door Arm
Rail Assembly
Hardware Bag Chassis Assembly Hardware Bag
Assembly Step 1
Assemble the Rail
ASSEMBLY SECTION: PAGES 8 - 11
The Chamberlain Group, Inc.
Screw Drive LM
3-Piece Rail
Turning Center Rail
8/5/94 - 8/10/94 - 1/12/95
Center Rail
Door End Rail
Rail
Sprocket
Trolley Rack
Sprocket End Rail
Rotate
1. Turn the opened rail carton upside down, emptying its
contents onto a level work surface.
2. Unfold the rails, taking care to avoid kinking the screw
rod joints.
3. Rotate the rail sections so that the flat side is down and
the screw side is up for all three lengths. Keep it clean
and free of debris while you are working.
CAUTION: During assembly, avoid pulling the rail
section housing the trolley rack away from the screw
rod. The rack is factory set about 9" from the end of the
screw rod to the center of the rack.
If the plastic liner slides part way out during assembly,
simply push it back in.
To avoid installation difficulties, do not run the garage
door opener until instructed to do so.

9
The Chamberlain Group, Inc.
Screw Drive LM
3-Piece Rail
Align Rails & Attach Support Brackets
8/7/94 - 8/10/94 - 9/12/94 - 1/12/95
Center Rail
Slide End
Rails Towards
Center Rail
Slide End
Rails Towards
Center Rail
Rail
Support
Brace
Lock
Nuts
Center
Rail
Rail Pin
Alignment
Hole
Rail
Support
Brace
Rail Pin
Rail Pin
Alignment
Hole
Alignment
Hole
1/4x20x1-3/4"
Bolts
1/4x20x1-3/4"
Bolts
Lock
Nuts
End
Rail
Door End
Sprocket End
4. Beginning with the sprocket end, straighten the two
rail sections so that the screw rod is in a straight line at
the joint. (Avoid handling the joints, which may have
sharp edges.)
5. Carefully slide the pins at the top edge of the rail into
the openings on the adjacent rail.
It is essential that
the rail assembly be on a level surface to achieve
proper alignment and to avoid damage to the pins.
6. Insert two 1/4"-20x1-3/4" bolts through the center
holes of a brace, and place its open length against the
rail at this joint, aligning the holes as shown. Position
another brace on the opposite side of the rail over the
bolts, add 1/4"-20 lock nuts, and hand tighten. Insert
two additional bolts and hand tighten.
7. Keeping the rail straight and on a level surface, grasp
the screw rods on each side of the remaining joint and
pivot into a straight line. Repeat steps 5 and 6.
8. With a 7/16 wrench, tighten bolts til snug, working
from the center holes of the braces to those further
from the joints. Do not overtighten.
1/4" - 20
Lock Nut
1/4"-20
Lock Nut
1/4" - 20 x 5/8"
Hex Screw
Hex Screw
5/16"-18 x 7/8" Nut 5/16"-18 Lock Washer 5/16"
Bolt
1/4-20x1-3/4" (8)
Hardware Shown Actual Size
Assembly Step 1 (Continued)
Assemble the Rail

10
Assembly Step 2
Fasten the Rail To the Power Unit
and Install the Trolley
The Chamberlain Group, Inc.
Screw Drive LM 114A1794
Attaching Rail Assembly & Coupling to Chassis
6/9/94 - 6/18/94 - 10/19/9
12/7/94
Rail
Sprocket
Rail
Assembly
Trolley
Coupling
Rail/Power Unit
Bracket
Lock Nuts
1/4"-20
Power Unit
Sprocket
Power
Unit
Foam Packaging
Hex Screws
1/4"-20x5/8"
1/4" - 20
Lock Nut
1/4"-20
Lock Nut
1/4" - 20 x 5/8"
Hex Screw
Hex Screw
5/16"-18 x 7/8" Nut 5/16"-18 Lock Washer 5/16"
Bolt
1/4-20x1-3/4" (8)
Hardware Shown Actual Size
As illustrated above, slide the trolley onto and along the
bottom of the rail until it snaps firmly in place.
Be certain
to install it facing correctly: the trolley release arm must
be horizontal (lock position), with its arrow pointed
away from the power unit.
• Working on a level surface, align the rail assembly with
the power unit, as shown.
• Slip the coupling over the rail sprocket.
• Slide the rail through the power unit bracket until the
coupling fits securely over the power unit sprocket.
• Align the two screw holes in the rail with those in the
power unit bracket. Insert two 1/4"-20x5/8" hex screws
and lock nuts. Tighten securely with a 7/16" socket
wrench.
NOTE: To aid in assembly and installation, replace
the foam packing around the power unit. Remove it
after Installation Step 5.

Assembly Step 3
Attach the Rail Brackets
11
IMPORTANT INSTALLATION INSTRUCTIONS
To reduce the risk of severe injury or death to persons:
1. READ AND FOLLOW ALL INSTALLATION INSTRUCTIONS
2. Install only on a properly balanced and lubricated garage door. An improperly balanced door may not
reverse and could result in severe injury or death. Repairs to cables, spring assemblies and other hardware
must be made by a professional service person before installing opener.
3. Disable all locks and remove all ropes connected to the garage door before installing the opener. Ropes
connected to a garage door can cause entanglement and death.
4. If possible, install door opener 7 feet or more above floor with the emergency release handle mounted 6
feet above the floor.
5. Do not connect the opener to power source until instructed to do so.
6. Locate the Door Control within sight of the door at a minimum height of 5 feet where small children
cannot reach and away from all moving parts of the door.
7. Install the User Safety Instruction Label on the wall adjacent to the control button and the Maintenance
Instruction Label in a prominent location on the inside of the garage door.
8. Upon completion of the installation, the door must reverse when it comes in contact with a one-inch high
object or a 2x4 laid flat on the floor.
9. Do not wear watches, rings or loose clothing while installing or servicing an opener. Jewelry or loose
clothing can be caught in the mechanism of the garage door or the opener.
• Align rail brackets to end of rail assembly, as shown.
• Insert two 1/4"-20 x 5/8" hex screws and lock nuts.
Tighten securely with a 7/16" socket.
Rail 
Brackets
Rail
1/4"-20
Lock Nuts
1/4"-20x5/8
Hex
Screws
The Chamberlain Group, Inc.
Attach Header Rail Bracket to Rail Assembly
Liftmaster Screw Drive #114A1794
6/5/94 - 12/5/94
You have now finished assembling your garage door opener. Please read the following warnings
before proceeding to the installation section:
1/4" - 20
Lock Nut
1/4"-20
Lock Nut
1/4" - 20 x 5/8"
Hex Screw
Hex Screw
5/16"-18 x 7/8" Nut 5/16"-18 Lock Washer 5/16"
Bolt
1/4-20x1-3/4" (8)
Hardware Shown Actual Size

Header
Wall
Ceiling
Sectional door
with curved track One-piece door with horizontal track
Track
Highest Point
of Travel
Door
Door
Track
SECTIONAL DOOR AND
ONE-PIECE DOOR WITH TRACK
3" Header
Wall
Highest Point
of Travel
3"
12
The Chamberlain Group, Inc.
Position Header Bracket
Sectional and One-Piece Track Installations
1/30/92 - 4/6/92
SECTIONAL DOOR AND
ONE-PIECE DOOR WITH TRACK
Vertical
Guideline
Finished
Ceiling
Vertical
Guideline
Header
Wall 2x4 Structural
Supports
SECTIONAL Door or
ONE PIECE Door with Track
• Close the door and mark the inside
vertical centerline of the garage door.
• Extend the line onto the header wall
above the door.
Remember, you can fasten the header
bracket within 2 feet of the left or right
of the door center
only if a torsion
spring or center bearing plate is in the
way; or you can attach it to the ceiling
(refer to page 14) when clearance is
minimal. (It may be mounted on the
wall upside down if necessary, to gain
approximately 1/2".)
If you need to install the header bracket on
a 2x4 (on wall or ceiling), use lag screws
(not supplied) to securely fasten the 2x4 to
structural supports as shown here and on
page 13.
• Open your door to the highest point of
travel as shown. Draw an intersecting
horizontal line on the header wall 3"
above the high point. This height will
provide travel clearance for the top edge
of the door.
• Door clearance brackets are available
for sectional doors when headroom
clearance is less than 2". See accessory
page 38.
Proceed to Step 2, page 14.
INSTALLATION SECTION: PAGES 12 – 27
Sectional door
with curved track One-piece door with horizontal track
Installation Step 1
Determine Header Bracket Location
Installation procedures vary according to garage
door types. Follow the instructions which apply to
your door.
If the header bracket is not rigidly fastened to a
structural support on the header wall or ceiling, the
safety reverse system may not work properly (see
page 30). The door might not reverse when required, and
could cause serious injury or death.
The garage door springs, cables, pulleys, brackets and
their hardware are under extreme tension. Do not attempt
to loosen, move or adjust them yourself. Serious
personal injury or death could result. Call for
professional garage door service.

The Chamberlain Group, Inc.
Position Header Bracket
One Piece Door Without Track
1/30/92 - 4/7/92
Header Wall Vertical
Centerline
Vertical
Centerline of
Garage Door
2x4
Unfinished
Ceiling
Structural Supports
2x4
Header Support
OPTIONAL CEILING MOUNT
FOR HEADER BRACKET
• Close the door and mark the inside
vertical centerline of your garage door.
Extend the line onto the header wall
above door.
If headroom clearance is minimal, you
can install the header bracket on the
ceiling. See page 14.
• If you need to install the header
bracket on a 2x4 (on wall or ceiling),
use lag screws (not supplied) to
securely fasten the 2x4 to structural
supports as shown.
• Open your door to the highest point of
travel as shown. Measure the distance
from the top of the door to the floor.
Subtract the actual height of the door.
Add 8" to the remainder. (See
Example).
• Close the door and draw an
intersecting horizontal line on the
header wall at the determined height.
If the total number of inches exceeds
the height available in your garage,
use the maximum height possible, or
refer to page 14 for ceiling
installation.
Proceed to Step 2, page 14.
EXAMPLE
Distance from top of door
(at highest point of travel) to floor . . . . . . . . . . . . .92"
Actual height of door . . . . . . . . . . . . . . . . . . . . . .-88"
Remainder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4"
Add . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .+8"
Bracket height on header wall . . . . . . . . . . . . . . .=12"
(Measure UP from top of CLOSED door.)
13
Door
Highest Point
of Travel
Header
Wall
Pivot
Distance
Header Wall
Highest Point
of Travel
Door
Floor Floor
Distance
Jamb
Hardware
The Chamberlain Group, Inc.
Position Header Bracket
Doors Without Track
1/30/92 - 4/7/92
One-piece door without track
pivot hardware
One-piece door without track
jamb hardware
ONE-PIECE Door Without Track
Read the Safety Instructions on page 12. They also apply to doors without tracks.

Lag Screws
5/16"x9x1-5/8"
Highest
Point of Travel
(of Garage Door)
Vertical
Center
Line
Header
Wall
Garage
Door
UP
CEILING MOUNT ONLY
Wall
Mounting Holes
Optional 
Wall Mounting
Holes
The nail hole is for
positioning only. 
You must use lag screws 
to mount the header bracket.
UP
CEILING MOUNT ONLY
Door
Spring
Header
Bracket
2x4
Structural
Support
Vertical
Center
Line
14
Fastening the Header Bracket to the Wall
• Center the bracket on the vertical guideline with the
bottom edge of the bracket on the horizontal line as
shown (with the arrow pointing toward the ceiling).
• Mark either set of bracket holes (do not use the holes
designated for ceiling mount). Drill 3/16" pilot holes
and fasten the bracket securely to a structural support
with the hardware provided.
• Extend the vertical guideline onto the ceiling as shown.
• Center the bracket on the vertical mark, no more than 6"
from the wall. Make sure the arrow is pointing toward
the wall. The bracket can be mounted flush against the
ceiling when clearance is minimal.
• Mark holes designated for ceiling mount only. Drill
3/16" pilot holes and fasten bracket securely to a
structural support with the hardware provided.
Fastening the Header Bracket to the Ceiling
Installation Step 2
Install the Header Bracket
You can attach the header bracket either to the
wall above the garage door, or to the ceiling.
Follow the instructions which will work best for
your particular requirements.
UP
CEILING MOUNT ONLY
Ceiling Mounting Holes
The nail hole is for 
positioning only.
You must use lag screws 
to mount the header bracket.
UP
Lag Screws
5/16"x9x1-5/8"
Garage
Door
Vertical
Center Line
Header
Wall
– Finished Ceiling –
Header
Bracket
6" 
Maximum
Vertical
Center Line
Door
Spring
Lag Screw
5/16"-9 x 1-5/8"
Hardware Shown Actual Size

Header Bracket
Rail Bracket
Foam Packaging
Opener Carton or
Temporary
Support
Header Wall
Garage
Door
Rail
Clevis Pin
5/16" x 2-3/4" Ring Fastener
Clevis Pin
5/16"x2-3/4 "
Ring Fastener
Header Bracket
Rail
Bracket
Rail
The Chamberlain Group, Inc.
Foam/Rail to Header Bracket
New Rail Assy.
12/6/94
• Position the opener on the garage floor below the
header bracket. Use packing material as a protective
base.
If the door spring is in the way you’ll need help. Have
someone hold the opener securely on a temporary
support to allow the rail to clear the spring.
• Position the rail bracket against the header bracket.
• Align the bracket holes and join with a clevis pin as
shown.
• Insert a ring fastener to secure.
15
Installation Step 3
Attach the Rail to the Header Bracket
Hardware Shown Actual Size

The safety reversing sensor must be connected and
aligned correctly before the garage door opener will
move in the down direction. This is a required safety
device and cannot be disabled.
Installation procedures are the same for sectional and
one-piece doors.
Be sure power to the opener is disconnected.
The sending eye transmits an invisible light beam to the
receiving eye. The units can be installed on either side of
the garage door as long as the sun never shines directly
into the receiving eye lens.
Look at the label on the connector end of each case to
identify the sensors.
The brackets must be connected and fastened so that the
sending and receiving eyes face each other as shown.
If an obstruction breaks the light beam while the garage
door is closing, the door will stop and reverse to full open
position and the opener lights will flash for 5 seconds.
The brackets must be securely fastened to a solid surface
such as the studs on either side of the door, or add a piece
of wood at each location if installing in masonry
construction.
Without a properly working safety reversing sensor,
persons (particularly children) could be injured or killed
by a closing garage door. Read and follow all
instructions.
To protect small children, install the safety reversing
sensor so that the beam will be no higher than 4"-6"
above the garage floor.
Disconnect power to the garage door opener before
installing the safety reversing sensor.
Invisible Light Beam
Protection Area
The Chamberlain Group, Inc.
Safety Sensor
Instruction Sheet Page 1
Protector System Disk #1 (Yellow)
11/5/91 - 1/15/92
Wing Nut
Sensor
Beam
4-6" max.
above floor
Sensor
Beam
4-6" max.
above floor
Facing the door from inside the garage
The invisible light beam path must be unobstructed. No
part of the garage door (or door tracks, springs, hinges,
rollers or other hardware) can interrupt the beam while
the door is closing. If it does, use a piece of wood to build
out each sensor mounting location to the minimum depth
required for light beam clearance.
16
The Safety Reversing Sensor
Information you'll need before you begin the installation of the safety reversing sensor

1/4 x 1-1/2"
Lag Screw
#10 - 32 x 3/8"
Screw 1/4" - 20
Lock Nut
#10 x 32
Lock Nut Staples 1/4" - 20 x 1/2"
Carriage Bolts
Installation Step 4
Install the Safety Reversing Sensor
(Receiving and Sending Eyes)
Mounting Bracket
With Square Holes
#10-32x3/8"
Screws
"C" Wrap
#10 - 32
Lock Nuts
Mounting Bracket
with Slot
1/4" - 20
Lock Nuts
1/4 x 1-1/2"
Lag Screws 1/4-20 x 1/2" Carriage Bolts
(with square shoulder)
Inside
Garage
Wall
"C" Wrap
Mounting Bracket
with Square Holes
The Chamberlain Group, Inc.
Safety Sensor Page 2
Safety Sensor Disk #1 (Yellow)
11/5/91 - 4/9/92
Inside
Garage
Wall
"C" Shaped
Wrap
Mounting Bracket
with Square Holes
1/4-20 x 1/2"
Carriage Bolts
1/4 " Lock Nuts
Drill 3/8"
Holes
Garage
Door Track
Garage DOOR Track Installation
Garage WALL or DOOR TRACK Installation
Garage WALL Installation
"C" Wrap
Inside
Garage
Wall
Mounting Bracket
with Square Holes
Garage
Floor
Mounting Bracket
with Slot
Alternate Wall Mount
Sensor
with wire
Indicator Light
Indicator Light
Inside
Garage
Wall
Alternate Floor Mount
Mounting Bracket
with Slot
Attach with
concrete anchors
(not provided)
Mounting Bracket
with Square Holes
"C" Wrap
Sensor with wire
Garage
Floor
17
Hardware Shown Actual Size
Figure 1
Figure 3 Figure 4
Figure 2
Figures 1 and 2 show assembly of brackets and "C" wrap
based on the recommended installation of the sensors on
each side of the garage door as shown on page 16.
However, Figures 3 and 4 are variations which may fit
your installation requirements better. Make sure the
wraps and brackets are aligned so the sensors will face
each other across the garage door.
1. Fasten the "C" wraps to the mounting brackets having
square holes, using the hardware shown in Figure 3.
2. Connect each assembly to a slotted bracket, using the
hardware shown in Figure 2.
Note the alignment of the brackets for left and right
sides of the door.
3. Finger tighten the lock nuts.
4. Use bracket mounting holes as a template to locate and
drill (2) 3/16" diameter pilot holes on both sides of the
garage door, 4"-6" above the floor
but not exceeding
6". (See warning on page 16.)
5. Attach bracket assemblies with 1/4"x1-1/2" lag screws
as shown in Figure 2.
6. Adjust right and left side bracket assemblies to the
same distance out from the mounting surface. Make
sure all door hardware obstructions are cleared.
Tighten the nuts securely.

18
Figure 5
1/4-20 x 1-1/2"
Hex Bolt
"C" Wrap
Sensor
with Wire
Wing
Nut
Indicator
Light
Installation Step 4 (Continued)
Install the Safety Reversing Sensor
The Chamberlain Group, Inc.
Screw Drive CGI
Sensor Wiring to Chassis
1/13/95
Invisible Light Beam
Protection Area Sensor
Sensor
Bell Wire
Foam
Packaging
Carton
2. Run wires along channels 
to power unit and pull taut.
1. Run wires from sensors to end of rail
at the door header. Cross & twist here to
help contain wires in channels on
top of rail.
3. Thread wires through tabs 
on top of Drive Shaft Cover.
4. With screwdriver blade, 
tuck wires snugly into channels.
Header
Bracket
Header
Wall
Sensor
Wire
Twist
Wires Sensor
Wire
Rail
Channel
Figure 6
7. Center each sensor unit in a “C”- wrap with lenses
pointing toward each other across the door (see
Figure 5).
8. Secure sensors with the hardware shown. Finger
tighten the wing nut on the
receiving eye to allow for
final adjustment. Securely tighten the sending eye
wing nut.
Recommended Wire Routing
1. Using insulated staples, run the wires from both
sensors to the rail at the door header (see Figure 6).
2. Cross and twist the two wires where they meet the rail
(see inset A). Run the wires inside the channels at the
top of the rail, along each side, to the power unit and
pull taut (see inset B). Do not use the lower (trolley)
channels.
NOTE: If your access door is near the garage door,
you may choose to install the door control at this time
and run the door control wire along the rail with the
sensor wires. Use one rail channel for the door control
wire and the other channel for both sensor wires. If
you choose this option, follow instructions 1-3
on page 21 now.
3. Thread the wires through the tabs on top of the drive
shaft cover.
4. With your screwdriver tip, tuck the wires snugly into
the rail channels. You will complete the wiring in
Installation Step 7.
1/4-20 x 1-1/2"
Hex Bolt Wing Nut
Hardware Shown Actual Size
A
B

Installation Step 5
Position the Opener
Follow instructions which apply to your door type
as illustrated.
To prevent damage to steel, aluminum, fiberglass or
glass panel doors, do not rest the opener on the door
without using a 2x4.
SECTIONAL Door or ONE-PIECE Door with Track
A 2x4 laid flat is convenient for setting an ideal door-
to-rail distance.
• Raise the opener onto a stepladder.
You will need help at this point if the ladder is not tall
enough.
• Open the door all the way and place a 2x4 laid flat on
the top section beneath the rail.
If the top panel hits the trolley when you raise the door,
pull down on the trolley release arm to disconnect the
inner and outer sections. The trolley can remain
disconnected until Step 13 is completed.
Rail 2x4
Door
Top of Opener
Header
Bracket
The Chamberlain Group, Inc.
Step 3 Position Opener Chassis
114A1794 Lift-Master One Piece Rail
5/9/94 - 6/1/94, 6/8/94 - 10/20/94
Top of Door
Foam
Packaging
Foam
Packaging
ONE-PIECE Door without Track
• With the door fully open and parallel to the floor,
measure the distance from the floor to the top of the
door.
• Using a stepladder as a support, raise the opener to the
same distance as the door from the floor (it will be at a
slight angle as shown).
• The top of the door should be level with the top of the
opener. Do not position the opener more than 3" above
this point.
Rail 2x4
Door
Top of Opener
Header
Bracket
The Chamberlain Group, Inc.
Step 3 Position Opener Chassis
114A1794 Lift-Master One Piece Rail
5/9/94 - 6/1/94, 6/8/94 - 10/20/94
Top of Door
Foam
Packaging
Foam
Packaging
19
WARNING
CAUTION
WARNING
WARNING
The Chamberlain Group, Inc.
Manual Disconnect
Liftmaster Screw Drive #114A1794
6/2/94, 6/15
NOTICE
Emergency
Release
Handle
(Pull at 45° angle)
Trolley
Trolley
Trolley
Release Arm
NOTICE
Trolley
ReleaseArm
(in Manual
Disconnect
Position)
Trolley
Trolley
Release Arm

Installation Step 6
Hang the Opener
Two representative installations are shown. Yours may
be different.
Hanging brackets should be angled, Figure
1, to provide rigid support. On finished ceilings, Figure 2,
attach a sturdy metal bracket to structural supports before
installing the opener.
The bracket and fastening hardware
are not supplied.
1. Measure the distance from each side of the opener to
the structural support.
2. Cut both pieces of the hanging bracket to required
lengths.
3. Drill 3/16" pilot holes in the structural supports.
4. Attach one end of each bracket to a support with
5/16"x1-5/8" lag screws.
5. Fasten the opener to the hanging brackets with
5/16" - 18x7/8" screws, lock washers and nuts.
6. Check to make sure the rail is centered over the door
(or in line with the header bracket if the bracket is not
centered above the door).
7. Remove the 2x4. Operate the door manually. If the
door hits the rail, raise the header bracket.
Measure
Distance
Lag Screws
5/16"x1-5/8"
Bracket
(Not Supplied)
Lag Screws
5/16"x1-5/8"
(Not Supplied)
5/16"-18x7/8" Screw
5/16" Lock Washer
5/16"-18 Nut
— FINISHED CEILING —
The Chamberlain Group, Inc.
Screw Drive Liftmaster #114A1794
Hang Opener Chassis
6/18/94
5/16"-18x7/8"
Hex Screws
5/16" Lock Washers
5/16"-18 Nuts
Hidden 
Support
5/16"-18x7/8" Screw
5/16" Lock Washer
5/16"-18 Nut
Structural
Supports
CONTROL
CENTER
CONTROL
CENTER
[
Preferred Range of
Bracket Placement
Preferred Range of
Bracket Placement
20
The opener could fall and injure someone if it is not
properly secured. Fasten the opener securel y to
structural supports of the garage.
Figure 1
Figure 2
Lag Screw
5/16"-9 x 1-5/8"
Hex Screw
5/16"- 18 x 7/8" Nut 5/16" - 18 Lockwasher 5/16"
Hardware Shown Actual Size
WARNING
CAUTION
WARNING
WARNING