
PROFESSIONAL INSTALLATION BY:
MODELS LDO33 & LDO50 
BELT-DRIVE OR CHAIN-DRIVE 
GARAGE DOOR OPENERS
HOMEOWNER’S INSTRUCTIONS
For Sectional and Jamb Type Doors
IMPORTANT SAFETY NOTES
Please read the instructions carefully! This garage door opener is designed to provide safe and reliable service if installed 
and tested as described in these instructions. A garage door is the largest mechanical appliance in a residence. Care 
must be taken to prevent injury or death during installation and operation of the garage door and garage door opener.
THE FOLLOWING FORMATS ARE USED FOR SAFETY NOTES IN THESE INSTRUCTIONS.
 WARNING 
This type of warning note is used to indicate 
possible mechanical hazards that may cause 
serious injuries or death.
CAUTION
This type of warning note is used to indicate 
the possibility of damage to the garage door or 
garage door opener.
IMPORTANT USER SAFETY INSTRUCTIONS
WARNING
A MOVING GARAGE DOOR CAN CAUSE INJURY OR DEATH!
TO REDUCE THE RISK OF DEATH OR SEVERE INJURY:
1 READ AND FOLLOW ALL INSTRUCTIONS.
2 NEVER LET CHILDREN OPERATE, OR PLAY WITH DOOR CONTROLS! KEEP REMOTE CONTROL 
AWAY FROM CHILDREN!
3 Always keep moving door in sight and away from people and objects until it is completely closed. NO 
ONE SHOULD CROSS THE PATH OF THE MOVING DOOR.
4 NEVER GO UNDER A STOPPED, PARTIALLY OPEN DOOR.
5 Test door opener monthly. The garage door MUST reverse on contact with a 1-1/2 inch object (or 
a 2x4 board laid fl at at the center of the door) on the fl oor. If adjusting either the force or the limit 
of travel, re-test the door opener. Failure to adjust the opener properly may cause severe injury or 
death.
6 If possible, use the red emergency release handle only when the door is closed. Use caution when 
using this release with the door open. Weak or broken springs may cause the door to fall rapidly, 
causing injury or death.
7 KEEP GARAGE DOORS PROPERLY BALANCED. (See Garage Door Opener Maintenance) An 
improperly balanced door could cause severe injury or death. Have a qualifi ed service person make 
repairs to cables, spring assembly and other hardware.
8
SAVE THESE INSTRUCTIONS.
1 Using the Garage Door Opener
Opening the Door
1 With the door in view, press the wall station’s UP/
DOWN ARROW button, the button assigned to the 
opener on the remote control, or enter a valid access 
code and press START/STOP on a remote keypad.
2 When the opener is activated, the opener’s light will 
turn on and the door will begin to open.
3 The door will open until the open limit is reached. If 
an obstacle is encountered (opener’s light fl ashes four 
times) while the door is opening, the door will stop.
4 The opener’s light will stay on for about fi ve minutes 
after the door stops.
Closing the Door
1 With the door in view, press the wall station’s UP/
DOWN ARROW button or the button assigned to the 
opener on the remote control, or enter a valid access 
code and press START/STOP on a remote keypad.
2 When the opener is activated, the opener’s light will 
turn on and the door will begin to close.
3 The door will close until the close limit is reached. If 
an obstacle is encountered (opener’s light fl ashes four 
times), or the safety beam is interrupted (opener’s light 
fl ashes three times) during closing, the door will stop, 
then re-open.
4 The opener’s light will stay on for about fi ve minutes 
after the door stops.
Stopping the Door Mid-travel
1 The door can be stopped immediately at any time 
by pressing the wall station’s UP/DOWN ARROW 
button, the remote control’s pushbutton, or press 
the START/STOP button on a remote keypad.
2 The next time the opener is activated, the door will 
move in the opposite direction.
Vacation Lock for Additional Security
1 Slide the wall station’s LOCK switch to the locked 
position to prevent remote controls from opening the 
door after the door is completely closed. The remotes 
can close the door, but not open it. The door can 
still be opened or closed by using the wall station’s 
UP/DOWN ARROW pushbutton.
➤ NOTE: To signal that the vacation switch is locked, 
the opener’s light will fl ash fi ve times if a remote is 
activated in an attempt to open the door.
2 Slide the wall station’s LOCK switch to the unlocked 
position to return the opener to normal operation.
Controlling the Opener’s Light
1 The opener’s light can be lit by pushing the wall 
station’s LIGHT button. The light will remain on until 
the LIGHT button is pressed again or the opener is 
cycled.
2 If the opener’s light is on, pushing the wall station’s 
LIGHT button will turn the opener’s light off.
Disconnecting the Door from the Opener
1 With the door in any position (preferably closed), 
carefully pull the red release handle. USE CAUTION 
IF THE DOOR IS OPEN, THE DOOR MAY DROP.
2 The disconnected door can be opened or closed 
manually.
3 To reconnect the opener, fl ip the release lever up. 
Raise or lower the door manually until the opener 
reconnects.
OPENING OR CLOSING THE DOOR
WALL STATION REMOTE CONTROL
PRESS THE
WALL STATION'S
UP/DOWN ARROW
SAFETY LIGHTING
WHENEVER OPERATING 
THE LIGHT WILL TURN ON 
FOR ABOUT 5 MINUTES
STOPPING THE DOOR
PREVENTING REMOTES 
FROM OPENING THE DOOR
LOCK UNLOCK
CONTROLLING THE 
OPENER'S LIGHT
PRESS THE LIGHT 
BUTTON TO TURN THE 
LIGHT ON OR OFF
IN CASE OF POWER FAILURE 
OR IF DOOR BECOMES OBSTRUCTED
PULL THE RED 
RELEASE HANDLE 
TO DISCONNECT 
THE OPENER FROM 
THE DOOR
PRESS A REMOTE
- OR -
CONTROL BUTTON
THE DOOR CAN BE STOPPED 
AT ANY POSITION USING THE
WALL STATION, REMOTE CONTROL,
SLIDE THE VACATION SWITCH
DOWN TO LOCK (REMOTES DISABLED)
OR UP TO UNLOCK (REMOTES NORMAL)
THE LIGHT WILL STAY ON UNTIL 
THE LIGHT BUTTON IS PRESSED 
OR THE OPENER IS CYCLED
FLIP THE LEVER UP 
AND RAISE OR
NOTICE
IF DOOR BECOMES OBSTRUCTED,
PULL DOWN ON HANDLE
LOWER THE DOOR 
TO RECONNECT 
THE OPENER
REMOTE 
KEYPAD
ENTER AN
ACCESS CODE
AND PRESS
- OR -
START/STOP
NOTE: A FLASHING
LIGHT INDICATES
TROUBLE
WALL 
STATION
REMOTE 
KEYPAD
REMOTE 
CONTROL
OR A REMOTE KEYPAD
NOTICE
IF DOOR BECOMES OBSTRUCTED,
PULL DOWN ON HANDLE
2 Remote Controls
This opener is supplied with a three-button remote control (the second and third buttons can be used to control an 
additional operator or gate if it contains a Linear MegaCode™ receiver). Additional single and multi-button remote 
controls can be purchased. An unlimited number of remote controls can be used with this operator. The short white 
wire on the back of the operator serves as an antenna for 
the remote controls. Do not cut off the white wire or the 
remote controls will not operate well.
 WARNING 
Children operating or playing with a garage 
door opener can injure themselves or others. 
The garage door could cause serious injury 
or death. Do not allow children to operate the 
remote control(s) or the wall station. A moving 
garage door could injure or kill someone under 
it. Activate the opener only when the door 
is clearly visible, free of obstructions and 
adjusted properly.
To Add a Remote Control 
1 Press the opener’s LEARN button. The red LEARN 
light will glow. The red light will stay on for about 15 
seconds. A remote must be added while the red 
LEARN light is still on. 
2 Send a signal from a remote. The red LEARN light and 
the opener’s light will fl ash once indicating that the 
opener has accepted the remote.
3 Repeat Steps 1 & 2 for any additional remote controls.
To Remove all Remote Controls
1 Press and hold the opener’s LEARN button for ten 
seconds or more.
2 Release the LEARN button. The red LEARN light will 
blink three times signaling that all of the remotes 
in the opener’s memory were erased. The red 
LEARN light will turn off, then turn on for 15 seconds. 
A remote control can be entered during this time using 
Step 2 above.
Testing
1 Before testing the remote control, straighten out the 
opener’s white antenna wire so it points up.
2 Stand clear of the door, press the remote control’s 
button and verify that the opener starts.
Replacing a Remote Control’s Batteries
When the red light on the remote glows dimly, or fails to light at 
all when the remote is activated, the batteries need replacing.
1 Open the remote’s case and remove the circuit board.
2 Replace old batteries with two Type 2032 batteries.
3 Re-assemble the remote.
3 Garage Door Opener Maintenance
Weather conditions may affect the door operation 
which could require some re-setting of the opener’s 
adjustments. Doors may swell and become heavier 
during wet periods, door hinges and rollers might bind 
during cold periods. To insure safe operation of the door, 
perform the following tests, including any additional test 
steps described.
Every Month
1 With the door closed, pull the red release handle to 
disconnect the opener from the door.
2 From outside the garage, slowly open the door 
manually all the way, and then close it all the way. 
Notice if there is any binding, sticking or rubbing. The 
door should move smoothly in both directions.
3 Raise the garage door about halfway up. Carefully 
release the door and see if the door balances. It 
should stay in place. Close the door.
➤ NOTE: If the garage door is unbalanced or the 
door travel isn’t smooth, have a qualifi ed garage door 
professional adjust or repair the door.
4 To reconnect the opener, fl ip the release lever up. 
Raise the door manually until the opener reconnects.
5 Perform the Safety Beam Test (Section 4).
6 Perform the Safety Reversal System Test as described 
in Steps 4-6 in Section 6.
After Servicing the Opener
1 Perform the Safety Beam Test (Section 4).
2 Perform the Open and Close Limit Adjustments 
(Section 5).
3 Perform the entire Door Force Safety System Test 
(Section 6).
Every 6 Months
Check the belt or chain tension.
• For belt-drive rails, examine the length of the tension 
spring in the traveler. It should be about 1” long.
• For chain-drive rails, examine the spacing between 
the turnbuckle and the rail. The turnbuckle should be 
slightly above the rail.
➤ NOTE: Too much or too little chain tension will cause 
excessive sprocket noise.
Chain Adjustment
If necessary, use the following steps to adjust the chain.
1 Hold the turnbuckle with a fl at blade screwdriver and 
loosen the two locknuts with a 7/16” end wrench.
2 Twist the turnbuckle to adjust the chain tension. Adjust 
the chain until the turnbuckle is sightly above the rail.
3 Hold the turnbuckle with a fl at blade screwdriver and 
tighten the two locknuts with a 7/16” end wrench.
Belt Adjustment
The tension spring in the traveler keeps the belt taut. The 
factory setting for the tension spring length is .9” long. If 
the tension spring is longer than 1”, adjust the belt.
1 Hold the traveler so the adjustment wheel is visible 
through the large slot.
2 Use a fl at blade screwdriver to turn the adjustment 
wheel to compress the tension spring until its length 
is between .9” and 1” long.
Every Year
Check the door hardware for lubrication needs. Lubricate 
door hinges, rollers and bearings according to door 
manufacturer’s recommended procedures.
PREPARING TO ADD A REMOTE
2
LEARN LIGHT WILL 
GLOW FOR 15 SECONDS
REMOTE MUST BE 
ENTERED WHILE LEARN 
LIGHT IS ON
1
PRESS THE LEARN BUTTON
ADDING A REMOTE
1
SEND A SIGNAL 
FROM A REMOTE
PRESS A
- OR -
BUTTON
REMOVING ALL REMOTES
1
PRESS THE LEARN BUTTON 
FOR 10 SECONDS OR MORE
REPLACING A REMOTE'S BATTERY
1
TWIST DIME IN  
SLOT TO OPEN  
CASE
3
CAREFULLY 
REMOVE THE 
CIRCUIT BOARD
4
REMOVE OLD 
BATTERIES AND 
DISPOSE OF THEM PROPERLY
ENTER A CODE 
AND PRESS 
START/STOP
NOTE: 
THE CIRCUIT BOARD WILL FIT ONLY ONE 
WAY INTO THE CASE. ALIGN THE PLASTIC POST  
IN THE CASE WITH THE HOLE IN THE CIRCUIT BOARD
5
INSERT TWO NEW 
TYPE 2032 BATTERIES 
PLUS SIDE UP THEN 
REASSEMBLE UNIT
DOW
N
UP
CLOSE LIMIT
DOWN
OPEN LIMIT
2
THE OPENER'S LIGHT AND
LEARN LIGHT WILL FLASH
ONCE WHEN REMOTE HAS
BEEN ACCEPTED
THE LEARN LIGHT 
WILL BLINK 3 TIMES 
SIGNALING THAT 
ALL REMOTES WERE 
REMOVED
2
LIFT OFF 
THE TOP OF 
THE CASE
U 
P
2
 WARNING 
Garage door hardware (springs, cables, 
brackets, pulleys, etc.) are under extreme 
pressure and tension. DO NOT ATTEMPT TO 
LOOSEN, TIGHTEN OR ADJUST ANY DOOR 
HARDWARE. CALL A QUALIFIED GARAGE DOOR 
INSTALLATION PROFESSIONAL!
 WARNING 
The garage door opener must not be installed 
and used on an unbalanced door. The opener’s 
internal door force sensor will not function 
properly on an unbalanced door. Risk of 
serious injury or death may result.
TO DISCONNECT OPENER
PULL THE RED 
RELEASE HANDLE 
TO DISCONNECT 
THE OPENER FROM 
THE DOOR
CHECKING THE DOOR BALANCE
NOTICE
IF DOOR BECOMES OBSTRUCTED,
PULL DOWN ON HANDLE
TO RECONNECT OPENER
FLIP THE LEVER UP 
AND RAISE OR 
LOWER THE DOOR 
TO RECONNECT 
THE OPENER
THE DOOR SHOULD 
BALANCE WITHOUT 
GOING UP OR DOWN
NOTICE
IF DOOR BECOMES OBSTRUCTED,
PULL DOWN ON HANDLE
 WARNING 
Always perform the entire Door Force Safety 
System Test (see Section 6) after making any 
adjustments to the opener.
TESTING THE SAFETY REVERSAL SYSTEM
ADJUSTING A CHAIN-DRIVE
TURNBUCKLE 
LOCKNUTS
LOCKNUTS
LOOSEN
HOLD TURNBUCKLE
TO OPENER
ADJUSTING A BELT-DRIVE
TURN THE ADJUSTMENT 
WHEEL UNTIL THE TENSION 
SPRING IS ABOUT 1" LONG
LOCKNUTS
TRAVELER
WITH FLAT BLADE 
SCREWDRIVER TO
TIGHTEN
BACKUP LOCKNUTS
ADJUSTMENT WHEEL
LOOSEN
TIGHTEN
TEST WITH SMALL OBSTACLE
THE DOOR MUST REVERSE 
WITHIN 2-SECONDS AFTER 
IMPACT WITH A 2 x 4 BOARD
2 x 4 BOARD LAID FLAT 
UNDER 
CENTER OF DOOR
TWIST
TURNBUCKLE
CHAIN
TIGHTEN
CHAIN
LOOSEN
MEASURE THE TENSION 
SPRING LENGTH

4 Testing the Infrared Safety Beam
The safety beam has two components, a sender and a receiver. The sender produces a narrow infrared beam that 
travels across the bottom of the door opening to the infrared receiver. If an object blocks the infrared beam while the 
door is closing, the door will stop, then reverse and fully open (the opener’s light will fl ash three times).
As a safety feature, the opener will ignore signals from all remote controls if the door is open and the 
infrared safety beam is blocked or out of alignment. In this case, the door can be forced closed by pressing 
and holding the wall station’s up/down arrow pushbutton (be sure the door area is in clear view).
 WARNING 
With the door closed, disengage the trolley 
from the chain during these alignment tests by 
pulling the red release handle.
Safety Beam Test
1 Check that the opener has power. The green lights on 
the sender and receiver should be lit.
Serious injury or death from a closing garage 
door may result because of failure to test and 
adjust safety reverse system. Repeat this test 
monthly and adjust as needed.
SAFETY BEAM INDICATORS
 WARNING 
2 If the receiver’s green light is on, but the red light is off, 
the receiver has power but is not detecting the infrared 
beam from the sender. The red light might fl ash when 
the beam is partially detected. This can be caused by 
mis-alignment or something blocking the beam. Adjust 
the safety beam sender and receiver while watching the 
receiver’s red light (stay out of the beam while aligning 
it). When the red light stays on, the beam is aligned.
SAFETY BEAM INDICATOR TABLE
GREEN ON POWER ON
GREEN OFF POWER OFF
RED ON BEAM OK - NO BLOCKAGE
RED OFF BEAM BLOCKED OR MIS-ALIGNED
RED FLASHING BEAM ALIGNED POORLY
GREEN LIGHT
ON = POWER ON 
OFF = POWER OFF
RED LIGHT
ON = BEAM ALIGNED, NO OBSTRUCTION 
OFF = BEAM NOT ALIGNED, OR OBSTRUCTION 
BLINKING = BEAM NEEDS BETTER ALIGNMENT
ADJUSTING THE BEAM
ADJUST THE SENDER 
AND RECEIVER UNTIL 
THE RED INDICATOR 
LIGHTS SOLID
RED LIGHT
GREEN LIGHT
➤ NOTE: If the receiver’s red light remains off, check 
for: 1) Dirt on the receiver’s lens, 2) Sunlight shining 
into the receiver’s lens, 3) A short in the safety beam 
wiring (from staples or at the opener terminals).
3 With the door closed and the opener disengaged 
CHECKING FOR REVERSAL
from the door, press the wall station’s UP/DOWN 
ARROW button to move the traveler (the part on the 
belt or chain that the trolley engages with) to the up 
position (away from the door).
4 Push the wall station’s UP/DOWN ARROW button again. 
While the traveler is moving to the down position (toward 
the door), block the safety beam. THE TRAVELER  
MUST STOP, THEN REVERSE TO THE UP POSITION. 
The opener’s light should fl ash three times.
5 Place an object in the path of the safety beam. Check 
that constant pressure is required on the wall station’s 
UP/DOWN ARROW button to cause the traveler 
to move toward the down position. Release the 
pushbutton before the opener stops; check that the 
BLOCK THE BEAM 
WHILE THE TRAVELER 
IS MOVING DOWN
CHECKING FORCED CLOSURE FEATURE
THE TRAVELER MUST REVERSE 
WHEN THE BEAM IS INTERRUPTED
DOWN
UP
TOWARD 
DOOR
TRAVELER
VERIFY THAT CONSTANT 
PRESSURE IS REQUIRED 
ON THE WALL STATION'S 
PUSHBUTTON TO MAKE 
THE TRAVELER GO DOWN 
TOWARD 
OPENER
traveler returns to the up position.
➤ NOTE: The garage door opener will not respond to a 
CLOSE command from a radio transmitter if the safety 
beam is blocked.
6 To reconnect the opener, fl ip the release lever up. 
Raise the door manually until the opener reconnects.
PLACE AN OBJECT 
IN THE BEAM'S PATH
RELEASE PUSHBUTTON 
BEFORE THE OPENER STOPS, 
THE TRAVELER SHOULD 
RETURN TO THE UP POSITION
5 Adjusting the Open and Close Limits
The limit adjustments that control how far the door will 
open or close are located on the side of the opener. The 
limits should be adjusted so the door opens just short of 
any door stops, and closes right at the fl oor level. Each 
full turn of a limit adjustment equals about 2-½” of door 
travel.
CAUTION
Set the open and close limits carefully. Setting 
the limits beyond the distance that the door can 
travel could cause damage to the door, the door 
hardware, or opener.
1 Star t with the door in the closed position.
2 Activate the remote control. Wait while the door moves 
to the open position and stops.
3 Examine the position of the door.
 • If the door needs to open more, turn the OPEN 
LIMIT adjustment clockwise ¼-turn (towards UP on 
the label) to raise the open limit.
 • If the door needs to open less, turn the OPEN LIMIT 
adjustment counterclockwise ¼-turn (towards DOWN 
on the label) to lower the open limit.
➤ NOTE: On jamb doors, set the open limit so the door 
stops just short of level (see fi gure).
4 Activate the remote control. Wait for the door to move 
down a few feet, then activate the remote control again 
to stop the door.
5 Repeat Steps 2-4 until the open limit is properly 
adjusted.
6 Activate the remote control. Wait while the door moves 
to the closed position and stops.
7 Examine the position of the door.
 • If the door needs to close more, turn the CLOSE 
LIMIT adjustment counterclockwise ¼-turn (towards 
DOWN on the label) to lower the close limit.
 • If the door needs to close less, turn the CLOSE 
LIMIT adjustment clockwise ¼-turn (towards UP on 
the label) to raise the close limit.
8 Activate the remote control. Wait for the door to move 
up a few feet, then activate the remote control again to 
stop the door.
9 Repeat Steps 6-8 until the close limit is properly 
adjusted.
➤ NOTE: If the door stops during opening or reverses 
during closing before reaching the limits, the door force 
adjustment needs to be set. Change the adjustment as 
described in the next section then return to this step to 
fi nish setting the limits.
CHECKING WHERE THE DOOR STOPS
DOWN
SETTING THE OPEN LIMIT ON A JAMB DOOR
JAMB DOOR
NOTE: SETTING THE OPEN LIMIT TOO HIGH WILL CAUSE 
THE OPENER TO "BUCK" WHEN STARTING DOWN
SETTING THE OPEN LIMIT
UP
DOWN
OPEN LIMIT
ADJUSTMENT
CHECKING WHERE THE DOOR STOPS
UP
DOWN
SETTING THE CLOSE LIMIT
UP
DOWN
CLOSE LIMIT
ADJUSTMENT
SET THE OPEN LIMIT SO THE DOOR 
STOPS JUST SHORT OF LEVEL
UP
EXAMINE THE SPOT WHERE 
THE DOOR STOPS OPENING
USE A SCREWDRIVER 
TO ADJUST THE LIMIT
EXAMINE THE SPOT WHERE 
DOOR STOPS CLOSING
USE A SCREWDRIVER 
TO ADJUST THE LIMIT
6 Testing & Adjusting the Door Force Safety System
The door force adjustments are located on the side of the opener. The door force adjustments must be properly 
set at all times. The CLOSE FORCE adjustment controls how much force is required to cause the door to reverse 
direction if an obstruction is encountered during closing. The OPEN FORCE adjustment controls how much force 
is required to stop the door if an obstruction is encountered during opening.
 WARNING 
SETTING THE DOOR FORCE
Too much door force will interfere with the 
proper operation of the safety system. SOMEONE 
COULD BE SERIOUSLY INJURED OR KILLED IF THE 
DOOR FORCE IS SET TOO HIGH. A closing door 
might not reverse properly when required and 
someone could be pinned under it. An opening 
door might not stop when going up and someone 
hanging on the door could get pinned between 
the door and the header. Do not increase the 
door force beyond what is required to move the 
door. DO NOT USE THE DOOR FORCE ADJUSTMENT 
TO COMPENSATE FOR A BINDING OR STICKING 
GARAGE DOOR. PERFORM THE SAFETY REVERSAL 
ADJUSTING THE CLOSE FORCE
UNDER-SETTING THE CLOSE FORCE
ADJUSTING THE OPEN FORCE
DECREASE CLOSE FORCE 
ADJUSTMENT UNTIL THE 
DOOR REVERSES MIDWAY 
WHILE GOING DOWN
SYSTEM TEST (STEPS 4-6) MONTHLY!
➤ NOTE: Read the following directions carefully before 
changing the door force adjustments. 
DECREASE
CLOSE FORCE
 WARNING 
Always perform the Door Force Safety System 
Test after making any adjustments to the 
opener.
Door Force Safety System Test
1 Start with the door open. Use the remote control to 
cycle the door during this test.
 Adjusting the Close Force
2 Turn the CLOSE FORCE adjustment 1/8-turn at a time 
in the DECREASE direction (counterclockwise) until 
the door stops and reverses mid travel while going 
down.
3 Turn the CLOSE FORCE adjustment 1/8-turn at a time 
in the INCREASE direction (clockwise) until the door 
fully closes without reversing.
 Safety Reversal System Test
4 Lay a 2 x 4 board fl at on the fl oor where it will be struck 
by the center of the door as it closes.
5 Verify that the door reverses when it strikes the board. 
The door must reverse within two seconds after 
striking the board.
➤ NOTE: If the door stops after encountering the board 
and does not reverse, the CLOSE FORCE needs to be 
DECREASED.
6 Repeat the Safety Reversal System Test until the door 
reverses within two seconds of striking the board.
 Adjusting the Open Force
7 Turn the OPEN FORCE adjustment 1/8-turn at a time 
in the DECREASE direction (counterclockwise) until 
the door stops mid travel while going up.
8 Turn the OPEN FORCE adjustment 1/8-turn at a time 
in the INCREASE direction (clockwise) until the door 
fully opens without stopping.
7 Replacing the Opener’s Lamp
If the opener’s safety lamp fails to light manually or when 
the opener is cycled, the light bulb needs replacing. Use 
the following steps to replace the light bulb.
1 Swing the light cover open to expose the light bulb and 
lamp socket.
2 Replace the light bulb with a 100 watt maximum rough 
service bulb (sometimes called a garage door bulb).
3 Swing the light cover closed, snapping it shut.
4 Press the wall station’s lamp button to test the lamp.
8 Troubleshooting
LAMP FLASHES 
TROUBLE CODE
1 FLASH
2 FLASHES
3 FLASHES
4 FLASHES
5 FLASHES
6 FLASHES
FCC NOTICE
Changes or modifi cations not expressly described in this manual or approved by the manufacturer could void the user’s authority to operate the 
equipment. This device complies with FCC Part 15. Operation is subject to the following two conditions: (1) This device may not cause harmful 
interference and (2) this device must accept any interference received, including interference that may cause undesired operation.
LIMITED WARRANTY
This Linear product is warranted to the original consumer against defects in material and workmanship for:
 MODEL  ELECTRONICS MECHANICAL  MOTOR  BELT 
 LDO50 1 year  5 years  Lifetime  Lifetime 
  LDO33  1 year  5 years  10 years  Lifetime
This product is warranted to the original consumer against defects in material and workmanship for the periods mentioned above. Linear 
will repair, or at its option, replace, any device that it fi nds requires service under this warranty, and will return the repaired or replaced 
device to the consumer at Linear’s cost. Devices must be sent to Linear for service at owner’s expense. This warranty does not apply 
to damage to the product from negligence, abuse, abnormal usage, misuse, accidents, normal wear or tear or due to failure to follow 
Seller’s instructions, or arising from improper installation, storage or maintenance. In no event will Linear be responsible for incidental, 
compensatory, punitive, consequential, indirect, special or other damages. The remedies provided by this warranty are exclusive. Some 
states do not allow the exclusion or limitation of incidental and consequential damages, so the above limitation or exclusion may not apply 
to you. Any warranties implied by law are limited to the time periods set forth above. Some states do not allow limitations on how long an 
implied warranty lasts, so the above limitation may not apply to you. This warranty gives you specifi c legal rights, and you may also have 
other rights which vary from state to state.
For warranty service and shipping instructions contact Linear at the phone number shown below. In order to be protected by this warranty, 
save your proof of purchase and send a copy with equipment should repair be required. All products returned for warranty service require 
a Return Product Authorization Number (RPA#). Contact Linear Technical Services at 1-800-421-1587 for an RPA# and other important 
details.
Copyright © 2007 Linear LLC  223710 B
PROBLEM CAUSE REMEDY
No problem
Door won’t close Shorted wall station wires
Door won’t close Safety beam obstacle
Door reverses 
or won’t open or 
close
Door won’t open 
from transmitter
Motor ran longer 
than 30 seconds
Remote control entered into 
memory
Open or Close force 
exceeded, or motor thermal 
shutdown
Remote was activated while 
vacation switch was locked
Mechanical or electronic 
failure
SETTING THE CLOSE FORCE
TESTING THE SAFETY REVERSAL SYSTEM
UNDER-SETTING THE OPEN FORCE SETTING THE OPEN FORCE
DECREASE
DECREASE OPEN FORCE 
ADJUSTMENT UNTIL THE 
DOOR STOPS MIDWAY 
WHILE GOING UP
REPLACING LAMP
SWING COVER OPEN
OPEN FORCE
INSTALL NEW BULB (UP TO 100 WATTS)
Add any additional remote controls 
(MegaCode™ type only)
Check wall station wires. Be sure both are 
connected to the terminal screws.Check for a 
staple in the wall station wires. Remove any 
staples compressing the wire.
Check for obstacles. Align the safety beam 
(Section 4)
Check for binding or un-balanced door. 
Adjust the door force (Section 6). If motor had 
thermal shutdown, wait 30 minutes and retry.
Unlock vacation switch on wall station
Call your local garage door professional
INCREASE CLOSE FORCE 
ADJUSTMENT UNTIL THE 
DOOR CLOSES FULLY 
WITHOUT REVERSING
INCREASE
CLOSE FORCE
TEST WITH SMALL OBSTACLE
THE DOOR MUST REVERSE 
WITHIN 2-SECONDS AFTER 
IMPACT WITH A 2 x 4 BOARD
2 x 4 BOARD LAID FLAT
CENTER OF DOOR
UNDER 
INCREASE OPEN FORCE 
ADJUSTMENT UNTIL THE 
DOOR OPENS FULLY 
WITHOUT STOPPING
INCREASE
OPEN FORCE