Chamberlain 1255GMR - 1/2HP User manual

GARAGE DOOR OPENER
Model 1255GMR – 1/2HP
Model 1245GMR – 1/3HP
For Residential Use Only
Complies with UL 325
regulations effective
January 1, 1993
®
Owner’s Manual
■Please read this manual and the enclosed safety materials carefully!
■Fasten the manual near the garage door after installation.
■The door WILL NOT CLOSE unless the Protector System®is connected and
properly aligned.
■Periodic checks of the opener are required to ensure safe operation.
■The model number label is located on the front panel of your opener.
The Chamberlain Group, Inc.
A DUCHOSSOIS ENTERPRISE
845 Larch Avenue
Elmhurst, Illinois 60126

2
Introduction Pages 2-5
Safety symbol and signal word review........................2
Preparing your garage door........................................3
Tools needed...............................................................3
Planning .....................................................................4
Carton inventory..........................................................5
Hardware inventory.....................................................5
Assembly Pages 6-7
Attach the T-rail to the motor unit................................6
Attach the chain to the sprocket..................................6
Tighten the chain.........................................................7
Installation Pages 7-23
Installation safety instructions.....................................7
Determine the header bracket location....................8-9
Install the header bracket..........................................10
Attach the T-rail to the header bracket......................11
Position the opener...................................................12
Hang the opener .......................................................13
Install the door control...............................................14
Install the light and lens ............................................15
Attach the emergency release rope and handle.......15
Electrical requirements..............................................16
Install the Protector System®................................17-19
Fasten the door bracket.......................................20-21
Connect the door arm to the trolley.....................22-23
Adjustment Pages 24-26
Adjust the travel limits...............................................24
Adjust the force.........................................................25
Test the safety reversal system.................................26
Test the Protector System®........................................26
Operation Pages 27-30
Operation safety instructions.....................................27
Using your garage door opener................................27
Using the wall-mounted door control ........................28
To open the door manually........................................28
Care of your garage door opener..............................29
Having a problem?...............................................29-30
Programming Pages 31-32
To add a hand-held remote control...........................31
To erase all codes.....................................................31
3-channel remotes.....................................................31
To add or change a Keyless Entry PIN.....................32
Repair Parts Pages 33-34
Rail assembly parts...................................................33
Installation parts........................................................33
Motor unit assembly parts.........................................34
Accessories 35
Repair Parts and Service 36
Warranty 36
TABLE OF CONTENTS
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.
When you see this Signal Word 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 cautionary statements
that accompany it. Read them carefully.
Mechanical
Electrical
WARNING
WARNING
CAUTION
INTRODUCTION
Safety Symbol
and Signal Word Review
This garage door opener 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.

3
Pliers
Wire Cutters
Claw Hammer
Hack Saw
Screwdriver Adjustable End Wrench
1/2" and 7/16" Sockets
and Wrench
Drill
Tape Measure
2
1
Stepladder
Pencil
3/16", 5/16" and
5/32" Drill Bits
Carpenter's
Level
To prevent damage to garage door and opener:
• ALWAYS disable locks before installing and operating
the opener.
• ONLY operate garage door opener at 120V, 60 Hz to
avoid malfunction and damage.
To prevent possible SERIOUS INJURY OR DEATH:
• ALWAYS call a trained door systems technician if
garage door binds, sticks, or is out of balance. An
unbalanced garage door may not reverse when
required.
• NEVER try to loosen, move or adjust garage 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
garage door BEFORE installing and operating garage
door opener to avoid entanglement.
Preparing your garage door
Before you begin:
• Disable locks.
• Remove any ropes connected to garage door.
•Complete the following test to make sure your
garage door is balanced and is not sticking or
binding:
1. Lift the door about halfway as shown. Release
the door. If balanced, it should stay in place,
supported entirely by its springs.
2. Raise and lower the door to see if there is any
binding or sticking.
If your door binds, sticks, or is out of balance, call
a trained door systems technician.
Tools needed
During assembly, installation and adjustment of the
opener, instructions will call for hand tools as
illustrated below.
WARNING
CAUTION
Sectional Door
One-Piece Door

Safety Reversing Sensor
Horizontal and vertical reinforcement
is needed for lightweight garage doors
(fiberglass, steel, aluminum,
door with glass panels, etc.).
See page 20 for details.
FINISHED CEILING
Support bracket &
fastening hardware
is required.
See page 13.
Motor Unit
Door
Center
Header Wall
Safety
Reversing
Sensor
Gap between floor and bottom of door
must not exceed 1/4"
Extension Spring
Torsion Spring
Access Door
OR
Slack in chain tension
is normal when
garage door is closed.
Wall-
mounted
Door
Control
4
SECTIONAL DOOR INSTALLATION
Planning
Identify the type and height of your garage door. Survey your garage area to see if any of the conditions below
apply to your installation. Additional materials may be required. You may find it helpful to refer back to this page
and the accompanying illustrations as you proceed with the installation of your opener.
FINISHED CEILING
Support bracket
& fastening
hardware is required.
See page 13.
Slack in chain tension
is normal when
garage door is closed.
Safety
Reversing Sensor
Header
Wall
Access
Door
Safety
Reversing Sensor
Gap between floor and bottom of
door must not exceed 1/4"
Wall-
mounted
Door
Control
Motor Unit
ONE-PIECE DOOR WITHOUT TRACK
Access
Door
Safety
Reversing Sensor
Safety
Reversing
Sensor
Slack in chain tension is normal when
garage door is closed
Gap between floor
and bottom of door
must not exceed 1/4"
ONE-PIECE DOOR WITH TRACK

5
SECURITY✚
Single-Function Remote Control (1)
Straight Door
Arm Section
Curved Door
Arm Section
Safety Labels
and
Literature
Header Bracket
UP
CEILING MOUNT ONLY
Sprocket Cover
2-Conductor Bell Wire
White & White/Red
Light Lens (1)
Remote Control
Visor Clip
Door Bracket
Door Control Button
with (2) 6ABx1-1/2" screws
(2) Safety Reversing Sensors
(1 Sending Eye and 1 Receiving Eye)
with
2-Conductor White & White/Black Bell Wire
attached
Safety Sensor
Bracket (2)
One-Piece
T-rail
Styrofoam
Trolley
Chain
& Cable
Cable
Pulley Bracket
Your garage door opener is packaged in two cartons
which contain the motor unit and all parts illustrated
below. Accessories will depend on the model
purchased. If anything is missing, carefully check the
packing material. Parts may be stuck in the foam.
Hardware for installation is also listed below.
Carton Inventory
INSTALLATION HARDWARE
Hex Screw 5/16"-18x7/8" (4)
Lag Screw 5/16"-9x1-5/8" (2)
Lag Screw 5/16"-18x1-7/8" (2)
Clevis Pin 5/16"x2-3/4" (1)
Clevis Pin 5/16"x1-1/4" (1)
Clevis Pin 5/16"x1" (1)
Nut 5/16"-18 (4)
Lock Washer 5/16" (4)
Self-Threading Screw 1/4"-14x5/8" (2)
Insulated Staples (30)
Ring Fastener (3)
Dry Wall Anchors (2)
Rope
Handle
Rail Grease
Carriage Bolt 1/4"-20x1/2" (2)
Wing Nut 1/4"-20 (2)

6
ASSEMBLY STEP 1
Attach the T-Rail to the Motor Unit
To avoid installation difficulties, do not run the
garage door opener until instructed to do so.
• Remove the two washered screws mounted in top
of motor unit.
• Position T-rail at a 45˚ angle to opener so one hole
in T-rail and motor unit line up.
• Thread one of the washered screws part way in.
Use only these screws! Use of any other screws
will cause serious damage to door opener.
• Align T-rail and styrofoam over sprocket. Cut tape
from T-rail, chain and styrofoam.
• REMOVE STYROFOAM.
USE ONLY THIS
TYPE AND SIZE
SCREW Washered Screw
5/16"-18x1/2"
Styrofoam
T-rail
Hole
To avoid serious damage to opener, ONLY use screws
mounted in top of motor unit.
CAUTION
ASSEMBLY STEP 2
Attach the Chain to the Sprocket
and Install the Sprocket Cover
• Position chain over the sprocket. If necessary,
loosen the outer nut on the trolley to obtain more
chain slack.
• Insert the second washered screw. CAUTION: Use
only the screw previously removed from motor
unit!
• Tighten both screws securely through the T-rail into
the motor unit as shown.
• Install the sprocket cover: Insert the back tab in the
slot. Squeeze the cover slightly and insert the front
tab in the slot on the mounting plate.
Proceed to Assembly Step 3.
To avoid possible SERIOUS INJURY to fingers from
moving garage door opener:
• ALWAYS keep hand clear of sprocket while operating
opener.
• Securely attach sprocket cover before operating.
USE ONLY THIS
TYPE AND SIZE
SCREW
Washered Screw
5/16"-18x1/2" Sprocket
Sprocket Cover
Mounting
Plate
Front Tab Slot
Back Tab Slot
WARNING

7
ASSEMBLY STEP 3
Tighten the Chain
• Spin the inner nut and lock washer down the
threaded shaft, away from the trolley.
• To tighten the chain, turn outer nut in the direction
shown. As you turn the nut, keep the chain from
twisting.
• When the chain is approximately 1/2" above the
base of the T-rail at its midpoint, re-tighten the inner
nut to secure the adjustment.
Sprocket noise can result if chain is either too
loose or too tight.
When installation is complete, you may notice some
chain droop with the door closed. This is normal. If
the chain returns to the position shown when the
door is open, do not re-adjust the chain.
NOTE: During future maintenance, ALWAYS pull the
emergency release handle to disconnect trolley
before adjusting chain.
You have now finished assembling your garage
door opener. Please read the following warnings
before proceeding to the installation section.
Lock
Washer
To Tighten Outer Nut Inner Nut
Trolley
Chain
Base of T-rail
1/2 Inch
To Tighten
Inner Nut
Outer Nut
IMPORTANT INSTALLATION INSTRUCTIONS
1. READ AND FOLLOW ALL INSTALLATION WARNINGS
AND INSTRUCTIONS.
2. Install garage door opener only on properly balanced
and lubricated garage 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 opener.
4. Disable all locks and remove all ropes connected to
garage door before installing opener to avoid
entanglement.
5. Install garage door opener 7 feet or more above floor.
6. Mount emergency release handle 6 feet above floor.
7. NEVER connect garage door opener to power source
until instructed to do so.
8. NEVER wear watches, rings or loose clothing while
installing or servicing opener. They could be caught in
garage door or opener mechanisms.
9. Install wall-mounted garage door control:
• within sight of the garage door
• out of reach of children at minimum height of 5 feet
• away from all moving parts of the door.
10. Place entrapment warning label on wall next to garage
door control.
11. Place manual release/safety reverse test label in plain
view on inside of garage door.
12. Upon completion of installation, test safety reversal
system. Door MUST reverse on contact with a one-
inch high object (or a 2x4 laid flat) on the floor.
To reduce the risk of severe injury or death:
WARNING

8
INSTALLATION STEP 1
Determine the Header Bracket
Location
Installation procedures vary according to garage door
types. Follow the instructions which apply to your
door.
SECTIONAL DOOR
AND ONE-PIECE DOOR WITH TRACK
1.Close the door and mark the inside vertical
centerline of the garage door.
2.Extend the line onto the header wall above the
door.
You can fasten the header bracket within 4 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 (see
page 10) 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 10.
3.Open your door to the highest point of travel as
shown. Draw an intersecting horizontal line on the
header wall 2" above the high point. This height
will provide travel clearance for the top edge of the
door.
Proceed to Step 2, page 10.
One-piece
door with
horizontal
track
To prevent possible SERIOUS INJURY or DEATH:
• Header bracket MUST be RIGIDLY fastened to
structural support on header wall or ceiling, otherwise
garage door might not reverse when required. DO NOT
install header bracket over drywall.
• Concrete anchors MUST be used if mounting header
bracket or 2x4 into masonry.
• NEVER try to loosen, move or adjust garage door,
springs, cables, pulleys, brackets, or their hardware, all
of which are under EXTREME tension.
• ALWAYS call a trained door systems technician if
garage door binds, sticks, or is out of balance. An
unbalanced garage door might not reverse when
required.
Header Wall
Ceiling
Track
Highest Point
of Travel
Door
2"
Sectional door
with curved
track
Door
Track
Header Wall
Highest Point
of Travel
2"
Vertical
Centerline
Finished
Ceiling
Vertical
Centerline
Header
Wall 2x4 Structural
Supports
WARNING

9
Header Wall Vertical
Centerline
Vertical
Centerline
of Garage
Door
2x4
Unfinished
Ceiling
2x4 OPTIONAL
CEILING MOUNT
FOR
HEADER BRACKET
Structural
Supports
ONE-PIECE DOOR WITHOUT TRACK
1.Close the door and mark the inside vertical
centerline of your garage door. Extend the line
onto the header wall above door, as shown.
If headroom clearance is minimal, you can install
the header bracket on the ceiling. See page 10.
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.
2.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).
3.Close the door and draw an intersecting horizontal
line on the header wall at the determined height.
NOTE: If the total number of inches exceeds the
height available in your garage, use the maximum
height possible, or refer to page 10 for ceiling
installation.
Door
Highest Point
of Travel
Header Wall
Pivot
Distance
Floor
One-piece door without track:
pivot hardware
Header Wall
Highest Point
of Travel
Door
Floor
Distance
Jamb
Hardware
One-piece door without track:
jamb hardware
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.)
Proceed to Step 2, page 10.

10
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. Do not install the header bracket
over drywall. If installing into masonry, use
concrete anchors (not provided).
WALL HEADER BRACKET INSTALLATION
• Center the bracket on the vertical centerline with
the bottom edge of the bracket on the horizontal
line as shown (with the arrow pointing toward the
ceiling).
• Mark the vertical 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.
Lag Screw
5/16"-9 x 1-5/8"
HARDWARE SHOWN ACTUAL SIZE
Lag Screws
5/16"x9x1-5/8"
Highest Point of
Garage Door Travel
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
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 Centerline
Header Wall
– Finished Ceiling –
Header
Bracket
6" Maximum
Vertical
Centerline
Door
Spring
CEILING HEADER BRACKET INSTALLATION
• Extend the vertical centerline 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 the side holes. Drill 3/16" pilot holes and
fasten bracket securely to a structural support with
the hardware provided.