Chamberlain LiftMaster Professional 3780 Instructions Manual Download Page 8

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9. Door stops but doesn't close completely:

Review Limit Adjustment section.

Repeat safety reverse test after any adjustment of door arm length,
close force or down limit.

10. Door opens but won't close:

• Check The Protector System™ (if you have installed this

accessory). If the light is blinking, correct alignment.

• If opener light does not blink and it is a new installation, check the

down force.

Repeat the safety reverse test after the adjustment is complete.

11. Opener light does not turn on:

Replace light bulb (40 Watts maximum). Replace burned out bulbs
with rough service light bulbs.

12. Opener light does not turn off:

There may be a defective earth at the ceiling or wall receptacle.
The unit must be earthed.

13. Opener strains or reversed during opening:

Door may be unbalanced or springs are broken. Close door and use
manual release rope and handle to disconnect trolley. Open and
close door manually. A properly balanced door will stay in any point
of travel while being supported entirely by its springs. If it does not,
call for professional garage door service to correct the problem. Do
not change force settings.

14. Opener motor hums briefly, then won't work:

• Garage door springs are broken. SEE ABOVE.

• If problem occurs on first operation of opener, door is locked.

Disable door lock. If chain was removed and reinstalled, the motor
may be out of phase. Remove chain; cycle motor to down position.
Observe drive sprocket. When it turns in clockwise direction and
stops in down position, re-install chain.

Repeat safety reverse test after adjustment is complete.

15. Opener won't activate due to power failure:

• Pull manual release rope and handle down and back to disconnect

trolley. Door can be opened and closed manually. When the power
is restored, pull the manual release handle straight down. The next
time the opener is activated, the trolley will reconnect.

• The Outside Quick Release accessory (if fitted) disconnects the

trolley from outside the garage in case of power failure.

When properly installed, opener will provide high performance with
a minimum of maintenance. The opener does not require additional
lubrication.

Limit Adjustments: These adjustments must be checked and
properly set when opener is installed. Only a screwdriver is
required. Weather conditions may cause some minor changes in the
door operation, requiring some re-adjustments, particularly during the
first year of operation.

Refer to the limit adjustments and force settings on page 5. Follow
the instructions carefully and repeat the safety reverse test after
any adjustment.

Remote Control Transmitter: The portable remote control may be
secured to a car sun visor with the clip provided. Additional remotes
can be purchased at any time for use in all vehicles using garage.
Refer to Accessories. Any new remotes must be set to the same
code as the original remote.

Remote Control Battery: The lithium batteries should produce
power for up to 5 years. If transmission range lessens, check the
battery.

To Change Battery: To replace batteries, use the visor clip or
screwdriver blade to pry open the case. Insert batteries positive side
up. To replace cover, snap shut along both sides. Do not dispose of
the old battery with household waste. Take batteries to a proper
disposal center.

CARE OF YOUR OPENER

Once a Month:

• Repeat safety reverse test. Make any necessary adjustments.

• Manually operate door. If it is unbalanced or binding, call for

professional garage door service.

• Check to be sure door opens and closes fully. Adjust Limits and/or

Force settings if necessary.

Once a Year:

• Oil door rollers, bearings and hinges. The opener does not require

additional lubrication. Do not grease the door tracks.

• GREASE THE RAIL AND THE TROLLEY.

MAINTENANCE OF YOUR OPENER