Got a new opener, the safety beam can only be tripped near one of the sensors or by placing a medium size box in the middle. Can’t trip it with my foot anywhere except near a sensor. Already replaced both sensors and the circuit board under warranty. The manual says to test with a box. Is this their attempt to prevent misaligned sensors and cats tripping the sensor? Next step is trying to get an engineer at Chamberlain on the phone. How many times have you tested a door by waving your foot near a sensor rather than the center? 
I have a Chamberlain and just tried it 5 times in several spots starting with the center and working towards both sensors and it tripped in every spot. Sounds like the sensors aren’t putting enough of a beam to be tripped at the center. My garage door is 17’ wide.
How old is yours?
The beam on mine is about two feet in diameter at the center. I can tape over the sending unit and just leave a pin hole opening in the tape and it improves the tripping with a wave of my foot but still not enough.
Im not sure on its age, it was here when i bought this house 5 years ago. My beam seems to be a lot more narrow than that. Almost like a laser. Mine won’t trip until my foot is almost clean in front of the sensor.
The only other thing I can think of is that they have some weird signal to the sensors that requires each one to be wired straight to the unit. Mine is prewired and has one sensor wired to the other and just one cable going to the unit.
Mine are wired separately and both wires go to the main drive unit.15965606746433286631014267336564|375x500
I see two cables in the picture. One is for the wall switch right? I see, now they are both headed towards the door.
Here is a shot inside. The red one that says wall is the wall switch and the blue and green lines are left and right sensors. They both go into the same plugs, but get the same power vs daisy chained.
Maybe the sensors are dirty being so close to the floor?
Sensors and circuit board replaced already under warranty but still same problem. They surely don’t think this is acceptable. I will call them again. Customer service is like all others but with an open ticket it might get someone’s attention.
After a tremendous amount of work with a new unit, original new unit and new board and sensors I have found that the garage floor paint is causing the problem with this new Chamberlain opener. Have video of proof but this site says a 51 second video is too big.
No problem on bare concrete, just with smooth garage floor paint. Not sure about the textured epoxy floors.
I am the same person as screen name bking. Have two for some reason. Have been a nachi member for 15 years.
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Wow, Bruce, first time I hear about something like that. There are a lot of painted garage floors out there, seems odd that yours would affect the sensors.
Did you run that through with the Manufactures?
Good luck with that ordeal.
If it trips with the manufacture’s recommended procedure it is all right.
It only trips real close to a sensor or if you put an object flush with the floor. Chamberlain has never heard of it until now. Probably partly due to their substandard method of checking the sensors, placing a big box on the floor. They agree that there is a problem. CPSC is going to know about it too. Their older opener I have on the door next to this one is not affected by the paint.
Paint a flat black strip of paint on the floor under the sensor’s
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That’s what I was thinking since the moving blanket that helped is black. Or take a drill motor with a wire wheel to it. Can’t do anything until all the interested parties have their say.
No kids or pets here so not an immediate issue.