20 Most Recent liftmaster Chamberlain Garage Door Opener Transmitter 300MC - Page 9 Questions & Answers

I have the very same problem. I have 2 Liftmaster 2500, 1/2HP openers installed in a 2 car garage. They are merely 15 feet apart in my garage ceiling. About 15months ago one stopped working by only the remotes. Went through the process of reprogramming the good one 1st and replaced batteries in the remotes, then trying to reprogram the one not working. Checked for radio interference near the one not working no LED or Halogen Lights, no wall tarnsformers, no cell phone interference etc... Nothing worked to on the 2nd opener in trying to get the remotes working again. I then purchased a New Logic Board, part number 41A5507-B. It was about $70 and then installed it in the 2nd opener which is not working. Tried to get the remotes programed - still nothing? I was baffled. I called Liftmaster - the only suggestion they gave me was was to totally unplug the GOOD opener and try the reprogramming up close to the 2nd door opener that's not been working. SURE enough - the Opener Remotes "Learned" okay and started working! Liftmaster Help line indicated that the thought to be GOOD opener actual had the defective Logic board and it was over powering the signal from the 2nd opener which was not working. I'll be taking the New Logic board and replacing it in the 1st opener.Thank you Liftmaster for the help !

If chain is too long just take out links. You DO NOT have to go out and buy a chain breaker. If you have a Dremel or grinder, just grind off the top of the pin and punch it thru and you are all set.

thanks w/d for getting right on my problem,my closer doesnt have lights at the bottom, it's a garage sale deal. works good otherwise exept I have to hold closer button on the wall to close.

Turn off circuits in house, one by one , and try. What about neighbors close by. Satellite dishes?

YOU CAN GO TO LIFTMASTER.COM TO DOWNLOAD THE MANUAL

One photo eye light should be green and the other light should be yellow.

SORRY TO SAY IT SOUNDS LIKE A FRIED CIRCUIT BOARD. LEAVE THE UNIT UNPLUGED FOR AT LEAST 30 MIN. & TRY AGAIN, IF SAME RESULTS I WOULD REPLACE THE BOARD.

HOPE THIS HELPS

Use the pull cord and disconnect the opener from the door.

Operate the opener and let the carrier slide back away from the door. Is the carrier moving smoothly when disconnected?

Next, lift the door by hand from the bottom to the top. Is it moving smoothly?

If not, lubricate the hubs of all the rollers on both sides of the door. Check the cable pulleys at the top sides of the door channel, lubricate them as well.

Are all cables in all the pulleys, there are 4.

Try this.

Gary

Is your house being hit by lightning? If so, there is nothing you can do.
If not, it could be a spike in the electrical service as well, I think. Try installing a high rated surge protector on the plug end. Some even have a guarantee that if the equipment protected gets damaged, they will pay for repair.

Let me know,
Gary

TAKE THE BATTERIES OUT FOR TEN TO FIFTEEN MINUTES GIVE THE UNIT TIME TO RESET ITSELF REPLACE BATTERIES .If that dos`nt work get the owners user`s GUIDE

Ensure that your electric eyes are aligned.
Disconnect the opener from the door and run the door down & up by hand. Does it move smoothly?
Most openers only require momentary contact to get them to open or close.
I have a doorbell button on mine in my house.

Gary

Sounds like it may be a broken spring. Look above the door at the coils on the steel rod and see if there is a separation of the torsion springs. Or if extension spring it will be hanging down on one side above the tracks. If it is a broken torsion spring I would advise calling someone with experience. If not what is the make and year of opener?

Sounds as if you have inadvertently turned on the vacation lock. If you have a lock button hold down for two seconds to turn off. Then your remote should start working again. May need re-programmed if you left the battery out for more than a minute or two.