20 Most Recent liftmaster Chamberlain Garage Door Opener Transmitter 300MC Questions & Answers


When you say sensors, are you talking about the photo-eye that checks if obstruction is in path of garage door?

1) You can buy sensors for $20-30. They seem generic

2) The new openers may be set up so by-pass is not an option.
Solution: In that case, you can move sensors above the garage door and put them face to face to see if that helps.

3) The way the sensors work is this. One side produces beam of light. Other side receives light. The receiver keeps a circuit closed at all times when light is received. If no light, then the circuit opens up and an electronic part interprets the lack of signal and turns off opener.

Solution: one side produces light. It does not have a switch. The other side has the switch. You can disconnect (or cut) a wire see which side has the light. The other side has the switch ... cut the 2 wires on the side with a switch, cap them off, and then see if opener works. Next twist the 2 wires together and see if opener works.

4) Fall-back position: Mark your wires and you can put it back the way it was.

liftmaster... | Answered on Dec 01, 2019


is the remote coded correctly, fuse on the remote board blown.or faulty remote board

liftmaster... | Answered on Sep 08, 2019


Get a best garage repair provider from http://www.aqualitygaragedoors.com/. I recently hired them and find them best in Miami.

liftmaster... | Answered on Jan 03, 2019


Something could be blocking the electric eye.they are down at ground level on both sides of the door

liftmaster... | Answered on Dec 29, 2018


Try reprograming the opener to each remote, if this doesn't work then the command/radio module in the opener is damaged and needs to be replaced. Hopefully you can find one or you will have to replace the whole garage door opener. Good luck.

liftmaster... | Answered on Dec 29, 2018


batteries in remote maybe?

liftmaster... | Answered on Feb 03, 2018


hi
check that the door is free from stifness

liftmaster... | Answered on Jan 03, 2018


http://support.liftmaster.com/articles/How_To/LiftMaster-receiver-and-remote-compatibility-1484145638635

I don't believe a universal remote will work. Here is a link to compatibility

liftmaster... | Answered on Nov 27, 2017


It will only take a 4 digit program code. After you program the code, and then enter that code to open the door, hit an additional number on the keypad. Some need the additional digit to act like an 'enter' key.

liftmaster... | Answered on Oct 03, 2017


Disconnect power to the opener! Then, with a dental tool or small screwdriver scrape off any corrosion etc from the contact in the center of the socket. Also note if it is lying flat against the bottom of the socket. If so, gently lift the center so it has some spring retention and rises up off the flat bottom of the socket.

liftmaster... | Answered on Sep 23, 2017


Check alignment of the obstruction sensors .... they shoot a light beam across the doorway about 6 inches above the floor. One is mounted on each side of the door track near the floor.

liftmaster... | Answered on Sep 23, 2017


This sounds like a similar problem that I had. The circuit board on the garage door motor has a capacitor that goes bad and this prevents the remotes from working. You can either buy a replacement circuit board online (for around $80 if I remember) or if you can solder, simply replace the capacitor for a few dollars. I answered a similar question on this site before after I went through the process. There are more details there. The capacitor in question was close to a heat producing component and over time it cooks.

liftmaster... | Answered on Sep 15, 2017


SORRY BUT THE GUY WHO GOT RID OF IT HAD THE RIGHT IDEA.
I DOUBT YOU CAN FIND A REMOTE AND IF IT HUMMS IT IS A POTENTIAL FIRE HAZARD.
SORRY I CAN'T GIVE YOU GOOD NEWS

liftmaster... | Answered on Sep 09, 2017

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