Question about liftmaster Chamberlain Garage Door Opener Transmitter 300MC

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Safety sensors Can i bypass the electric eye safety sensors? I do not have a green light on the sensors. The green reset light on the back of the garage door opener will not stay on.

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Pull the contact wires off the back of the eyes. If this is found helpful, please post as such. Post as fixya if it gets the desired effect. TY

Posted on Jan 16, 2009

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Posted on Jan 02, 2017

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D1000 closes holding wall button only, sensors clean and same, bypassed them it still did it, remotes don't work


This sounds like a problem with the safety sensors; either due to a blocked path between the safety sensors, condensation, mis-alignment, dirty eyes, loose wires at the sensors or at the motor head, or just bad safety sensors. When the infra-red safety sensors are malfunctioning, usually one of the sensor lights will be blinking or a blinking red light will show rather than green or amber. The sensor lights need to be solid and not dim or flickering.

When the sensors are at fault, the remotes cannot close the garage door; they can only open it. You may find that the door will only move an inch or so in the close direction. When this happens, your garage door will only close by holding down on the wall button until the door fully closes. This method is the only way to override the safety sensors and close the door. This is also a direct clue that the safety sensors are the problem.

Also, try unplugging the garage door opener and re-plugging the unit back into the outlet. This can act as a reset and may reset the sensors. If none of this works then you may have to replace the sensors or possibly the logic board inside the motor unit.

Aug 20, 2017 | Building Materials

2 Answers

How do you align the safety sensors for a lifmaster garage door


The indicator lights in both sending and receiving eyes with glow steady if wiring and alignment are correct.
http://waterheatertimer.org/pdf/Liftmaster-safety-reversing-system.pdf
Connect the wires together on safety sensor receiver (with green indicator light), so it by-passes safety system.
The safety system consists of sender with amber light, and receiver with green indicator. Receiver must receive light in order to keep switch circuit closed. If receiver receives no light from sender, then switch opens, and garage door will not function.
Connect both wires on receiver will simulate the closed switch, as if receiver is receiving beam of light.
You can order replacement sensors from amazon

May 28, 2013 | Electrical Supplies

1 Answer

Door will not operate unless you hold down button


I am presuming the following: is it that the door will not operate unless you hold down the button to "close the door"? And the button you are pressing is the hardwired wall button or control inside the garage correct? And if you try to close the garage door with the remote the overhead lights flash off and on or the motor make a clicking sound (about 5 clicks?)
The problem is either an obstruction of the safety sensors at the bottom of the door or, one or both sensor eyes are out of alignment. If you look closely at both safety sensor eyes on the part that faces into the garage, you should see a glowing LED. One side will be an Amber color and the other Green. If one is lit (amber) but the other is not (green), that is an indication that the beam is not being received by the receiving eye (amber).
If there is no obvious obstruction (check for spider webs, dust, try cleaning the clear lenses facing each other, etc,) Try re-aligning the sensors. When they are properly aligned the Green LED will be lit. Now, check the motor for operation.
If you have difficulty getting the transmitter eye (green LED) to light, try closing the door at the wall button, then, pull the red emergency release handle to disengage the door.
Now, try operating the motor unit with the door disconnected while using the hand held transmitter. If the motor unit operates to the close position while the door is closed but not when opened, then that sounds like there is sufficient light entering the garage to "Wash" the transmitter beam out so the receiving eye does not get it.
Contact Chamberlain/Liftmaster for Sensor eye blinder shields that can be easily installed by you. (they just snap on) If neither LED is lit, make sure that the wire to the sensor(s) has not been cut off at the sensor itself. If that checks out, check the connection at the logic board. Make sure that both wires are securely connected.
If after checking all of that, and you do not have either of the LEDs on, then disconnect the safety sensor wires from the motor unit's logic board. Then take a 2" piece of bell wire and jump it across the two terminals for the safety sensors. If the unit operates normally when using the hand held transmitter, then the problem is likely: a) Bad safety sensors b) Broken wire to one or both sensors
To check if the safety sensors are good:
Remove both sensors from their mounting brackets. measure about 8" to 12" of wire from the back of the sensors and cut. You should have about 8 - 12 inches of wire on each. Now, separate and strip the insulation from each and then match the white striped wires and twist them together, and do the same with the solid non-striped wires. Take the sensors up to the motor head and connect the spliced wires to their respective positions on the logic board. Now, Point the two sensors directly at each other (its okay if the clear lens part are touching each other) Check if both LEDS are now lit. 1) If YES; then the sensors are good, the wire to them is broken somewhere; [FIX] replace the wires for both sides. 2) If NO: then the safety sensors need to be replaced. [FIX] Replace the sensors, contact Chamberlain / Liftmaster for replacement parts. You will need your garage door opener's model # which can be found under the light bulb or light fixture on the opposite side of the logic board. Having the model # speeds up the parts search for you.
I hope this helps you out. [I have been factory trained on residential and commercial garage door openers by Chamberlain / Liftmaster and have been providing installation and tech support on them for over five years. Prior to that I used to install and repair these units, and I've done that for nearly seven years.]

May 18, 2011 | Chamberlain & Liftmaster Garage Doors

1 Answer

My garage door opens fine by pushing the button once, but won't close unless I hold the button down through the whole down motion.


The problem is with your safety "eyes" on your system. I bet the lights on the opener click rapidly once in awhile as well. Make sure that both lights on safety "eyes" sensors are on (one of them is amber and the other is green). If not, check the wiring onto the opener - white wire should go to white and gray to gray. This system will not operate properly if it cannot sense the proper functioning of the safety "eyes" sensors.

Oct 07, 2010 | Chamberlain 1/2-HP Whisper Drive Belt...

1 Answer

Can't close my garage door Mine will go down if I hold the wall button until it is all the way down, but it goes right back up. i removed the cob webs and checked the sensors. is there suppose to be a...


HOLDING DOWN THE WALL BUTTON OVERRIDES THE SAFETY EYES.
WHEN HOLDING IT DOWN MAKES THE DOOR CLOSE PROPERLY THE PROBLEM IS IN THE SAFETY EYES.

THERE ARE LED'S THEY SHOULD BOTH BE LIT - CHECK FOR A LOOSE OR BROKEN WIRE.
ARE THE EYES WIRED CORRECTLY?
ARE THEY AIMED AT EACH OTHER?

IF ALL ELSE FAILS GET SOME DOORBELL WIRE AND BYPASS THE EXISTING WIRES AS A TEST - BE SURE TO CHECK THE POLARITY & LOOSE CONNECTIONS.

HOPE THIS HELPS

Jun 10, 2009 | Chamberlain Powerdrive PD422D 1/2 HP...

1 Answer

We have 2 sensors. 1 has a green light and the other has no light


Your safety eyes are out of ajustment. Make sure that the eyes are pointing directly at each other. A light will come on on each eye when they are properly aligned. The only other thing that could be wrong is that one of the safety eyes could be bad, and the only thing you can do is replace the eyes. 99% of the time the problem is an alignment issue. By holding down the wall button, you are overriding the safety eyes.

Mar 05, 2009 | Sears Craftsman LiftMaster Chamberlain...

1 Answer

Pressing remotes the door won't go u[


It sounds like you have the lock enguaged. When it is flashing it locks out all remote access. Hold the lock button for 3 seconds. The green light should go solid. On the issue of closing, it is most likely a safety eye issue. Hold down the wall button. If it closes it is the safety eyes. Holding the button overrides the safety eyes. Make sure that thelight on both eyes are both lit.

Jan 27, 2009 | Sears Craftsman LiftMaster Chamberlain...

2 Answers

One sensor light is blinking green, the other sensor light is bli


the safety eyes are wired wrong on the back of the opener. Check the wire locations.

Nov 24, 2008 | Sears Craftsman LiftMaster Chamberlain...

5 Answers

Programing limits on a Grifco MK3 Garage door Operator


It has the "Protector System" (safety sensors). chec the sensor indicator light on the receivinng eye the green light had a slight flicker.cleaned both the sending eye and receiving eye lens of dust and cob webs, then realigned the receiving sensor for a steady green indicator light. then check the door function it now works fine.over time, temperature, and viberation the sensors become dirty and get out of alignment, as no one had tampered with the sensor alignment prior to this. Hope this works for you.

Nov 21, 2008 | Sears Craftsman LiftMaster Chamberlain...

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