[Charles]

No joy on finding a schematic for a LiftMaster control board. Thought I'd
ask here.

The remotes (4 of them) work flawlessly to open the door. They also work to
close the door, but only after the built-in overhead light turns off. That
takes about 2 minutes.

Checked the obvious for the beam sensor: sensor obstruction, sensor wiring,
sensor lenses, sensor alignment. The wall switch always works.

Any ideas?

Thanks!

[tm]

"Charles" wrote in message
...
No joy on finding a schematic for a LiftMaster control board. Thought I'd
ask here.

The remotes (4 of them) work flawlessly to open the door. They also work
to close the door, but only after the built-in overhead light turns off.
That takes about 2 minutes.

Checked the obvious for the beam sensor: sensor obstruction, sensor
wiring, sensor lenses, sensor alignment. The wall switch always works.

Any ideas?

Thanks!

Are you using CFLs in the unit?

[Charles]

"tm" wrote in message ...


"Charles" wrote in message
...
No joy on finding a schematic for a LiftMaster control board. Thought I'd
ask here.

The remotes (4 of them) work flawlessly to open the door. They also work
to close the door, but only after the built-in overhead light turns off.
That takes about 2 minutes.

Checked the obvious for the beam sensor: sensor obstruction, sensor
wiring, sensor lenses, sensor alignment. The wall switch always works.

Any ideas?

Thanks!

Are you using CFLs in the unit?

No, just an ordinary incandescent. I see your point ... high frequency
interference.

[John Keiser]

An older unit?
My limited experience with a 10 year old Genie opener with failed control
board: check carefully for a corroded trace. [Perhaps more expecetd here in
Hawaii but could happen anywhere as the Genie board was not well protected
from the environment.]


"Charles" wrote in message
...


"tm" wrote in message ...


"Charles" wrote in message
...
No joy on finding a schematic for a LiftMaster control board. Thought
I'd ask here.

The remotes (4 of them) work flawlessly to open the door. They also work
to close the door, but only after the built-in overhead light turns off.
That takes about 2 minutes.

Checked the obvious for the beam sensor: sensor obstruction, sensor
wiring, sensor lenses, sensor alignment. The wall switch always works.

Any ideas?

Thanks!

Are you using CFLs in the unit?

No, just an ordinary incandescent. I see your point ... high frequency
interference.

[tm]

"John Keiser" wrote in message
...
An older unit?
My limited experience with a 10 year old Genie opener with failed control
board: check carefully for a corroded trace. [Perhaps more expecetd here
in Hawaii but could happen anywhere as the Genie board was not well
protected from the environment.]


"Charles" wrote in message
...


"tm" wrote in message ...


"Charles" wrote in message
...
No joy on finding a schematic for a LiftMaster control board. Thought
I'd ask here.

The remotes (4 of them) work flawlessly to open the door. They also
work to close the door, but only after the built-in overhead light turns
off. That takes about 2 minutes.

Checked the obvious for the beam sensor: sensor obstruction, sensor
wiring, sensor lenses, sensor alignment. The wall switch always works.

Any ideas?

Thanks!

Are you using CFLs in the unit?

No, just an ordinary incandescent. I see your point ... high frequency
interference.


If you turn the light on before opening the door will it cause the same
problem? How about if you remove the bulbs?

[Jeff Liebermann]

On Wed, 6 Mar 2013 18:02:37 -0500, "Charles"
wrote:

No joy on finding a schematic for a LiftMaster control board. Thought I'd
ask here.

Model number?
http://www.liftmaster.com

The remotes (4 of them) work flawlessly to open the door. They also work to
close the door, but only after the built-in overhead light turns off. That
takes about 2 minutes.

The off time on the light should be adjustable. That should help with
the testing.

Checked the obvious for the beam sensor: sensor obstruction, sensor wiring,
sensor lenses, sensor alignment. The wall switch always works.

Check the "Protector" obstruction sensor again. It's optical, where
there's an IR beam going across the garage door opening detects pets
and people. If you break the beam, the overhead light comes on, and
the garage door stops. The overhead light may be overloading the
optical obstruction detector, which pretends that there's an
obstruction, until the overhead light goes out. Put a smaller light
bulb in the overhead, or just remove the bulb temporarily to see if
something optical is associated with the problem. If that's the case,
put a paper or plastic pipe over the optical detector to block light
from the overhead bulb.


--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

[[email protected]]

On Wednesday, March 6, 2013 4:02:37 PM UTC-7, Charles wrote:

The remotes (4 of them) work flawlessly to open the door.
They also work to close the door, but only after the built-in
overhead light turns off. That takes about 2 minutes.

Checked the obvious for the beam sensor: sensor obstruction,
sensor wiring, sensor lenses, sensor alignment. The wall switch
always works.

Any luck at Sears.com or ElektroTanya.com ? Liftmaster is the same
as Chamberlain and Sears Craftsman, only with a one-piece overhead
rail.

I found that the optical sensor can seem OK and its LED seems to
glow steadily, but in reality it may be cutting in and out very
rapidly because of a bad wiring connection from motor vibration,
which also eventually cracks some of the solder, all over.

If your wall button isn't lighted, it can cause problems with the
optical sensor -- something about the lack of a pull-up or pull-down
resistor. Chamberlain used to give out lighted wall consoles to
fix this problem, but if you phone them, talk to an electronics
tech instead of an installation tech.

Could the driver for the relay of the overhead light be at fault? I
had a protective diode across a relay coil blow and cause intermittent
glitches with an opener.

[[email protected]]

On Mar 6, 5:02*pm, "Charles" wrote:
No joy on finding a schematic for a LiftMaster control board. *Thought I'd
ask here.

The remotes (4 of them) work flawlessly to open the door. *They also work to
close the door, but only after the built-in overhead light turns off. *That
takes about 2 minutes.

Checked the obvious for the beam sensor: sensor obstruction, sensor wiring,
sensor lenses, sensor alignment. *The wall switch always works.

Any ideas?

Thanks!

Unscrew the overhead light and see what happens and let us know.

[Charles]

" wrote in message
...

On Mar 6, 5:02 pm, "Charles" wrote:
No joy on finding a schematic for a LiftMaster control board. Thought I'd
ask here.

The remotes (4 of them) work flawlessly to open the door. They also work
to
close the door, but only after the built-in overhead light turns off.
That
takes about 2 minutes.

Checked the obvious for the beam sensor: sensor obstruction, sensor
wiring,
sensor lenses, sensor alignment. The wall switch always works.

Any ideas?

Thanks!

Unscrew the overhead light and see what happens and let us know.

No effect.