If the main light flashes 10 times and the door reverses to the open position, it is a door sensor problem. Tweak them a little. Sometimes the light in one of the sensors is flickering ever so slightly and will cause this problem. Very hard to see. If the main light is not flashing 10 times you could have a bad RPM sensor which is a small circuit board just in front of the motor.

don,
Thank you for the quick reply. The main light certainly doesn't flash 10 times that I or my wife have seen. I'm rather certain that the sensor lights are solid, yet will double check tonight. Your diagnosis is right in line with the on-phone tech I spoke with just yesterday. Upon explaining the same information I shared above, she mentioned that I could have a bad "Logic Board". Is this what you're referring to when you mentioned "RPM Sensor"? As I believe, by viewing the opener diagram, near the motor is the same/similar location as the Logic Board. Thanks

No it is a separate board. The logic board is the main brains of the opener and is on the end where all those white wires go. The RPM sensor board is inside and you must remove the cover from the motor unit to see it.

Before you rush out and spend money let's run through your listed symptoms.

Number 1 says "lights blinking when this happens." Is this blinking of lights the main lights? If it is and they blink 10 times it is a door sensor problem. Nothing else will cause this.

Number 3 says "shuts off altogether after repeated attempts." This is normal. The motor has a thermal protector.

On the rear of the motor unit you will find the 'down force' adjustment. Increase this by a 1/4 turn and try.

don,
Yes, the blinking lights are the main two bulbs that turn on during normal operation of the garage door. Good to know that the system has a "fail-safe" function that protects it after failed attempts.. Lastly, I'll try increasing the down-force, although, yesterday when I was reconnecting the door to the opener (the opener piece that allows the door to disconnect from the opener) the chain had no load (because the door was not connected) and it still gave me the same problem closing. I'll adjust the down-force tonight and let you know what I discover. Thanks again. Fred

It is looking more and more like your logic board. The part number for it is on the end of the motor unit with all the white wires. It starts with 41A. You can check with that for the cost. Not cheap.

Don,
I've re-adjusted the downforce a 1/4 turn and tweaked the downtravel, and had the same problems as before. Just that the door barely moved now before stopping, was powering off a lot(themal protecting the motor). What I did notice, that I had not noticed before, was that the chain was extremely tight. I loosened the chain to a respectable tension, trimmed the "exposed" wire to the sensors (that plug into the unit) to the recommend length of 7/16in., and after some more fidd'ling around, tested the garage door again. IT WORKED PERFECT FOR ABOUT 10 times in a row and then started acting up again, just not acting up near as bad. It's managable now, the wife is no longer stressed out... By the way, the lights on the sensors are solid,... no flickering at all. Also, I was able to open one side of the unit and the white plastic gears inside appear perfect in condition... no grinding evident.. Do you still think the logic board is failing? Thanks...

This darned thing is going to be hard to pin down but if you can catch it when it is acting up and you have a volt meter you can check for this.

Check for 5vdc between terminals 2 and 3 on the rear of the motor unit. If there is no voltage or if it is greater than 6vdc the logic board is bad.

Good luck.

Don,
Thanks for the additional advise. I was too busy last night to test the voltage. I'll see if I can make some time tonight. I'll certainly get back to you to let you know how it goes.. Thanks.

Don,
Thank you for your patience. I finally had some time last night to take the garage-door opener apart a bit and test the voltage with my multi-meter. I had some difficulty figuring out which terminals were 2 and 3. I tested several wires and combinations between the white, blue, and red wires that came off the back of the motor. My voltage readings were no higher than 1.5vdc. Again, I may not have had the wire combinations correct, though I tried many different combinations. Also, the garage-door opener was working perfectly: could not get it to act up�. Here�s what I discovered� There is one white, red, and blue wire that come off the back of the motor. The white wire goes directly to a connection point (for power, as it is the power line that comes into the unit and branches off to the motor and etc.) and branches off to the logic board, lighting and other components such as the up/down force and up/down travel�. The blue and red wires come off the motor and hook to a cylindrical component (about 4in. in length and 1in. in diameter) and come out of the same cylindrical component at different connection points and those connect to the what I believe is the logic board.. In other words, there�s a red and blue "in" connection point as well as a red and blue "out" connection point� I�m not certain as to exactly where I need to test for voltage�. Can�t get the opener to act up now that the weather is warmer� Thanks for your help and additional advise�

Fred

You"ll have to wait until the opener starts acting up again. The terminals to check are on the rear of the motor unit. They are marked 1, 2 & 3 and are where all those white wires go. Not inside the motor unit.

Don,
Haven't forgotten about updating you.. Though I was unable to test the terminals correctly, I believe that I discovered what may have been my problem all along. Since making this adjustment, I have not had one single issue with the garage door opener acting up when closing. I believe my problem was the connection with the wiring plugging into the logic board. They appeared to be pinched. I re-adjusted the position of them and pressed them into the logic board firmly, and I've not had a problem since. I guess after four years of being in that position and enduring all the vibrations from the door-opener motor, the wiring worked itself free a bit; giving me a bad connection. Again, I believe this to have been my problem as it makes complete sense. Hopefully this was my "cheap" fix (just time invested) and I'll be able to get a few more years out of the door opener before something breaks down. Thanks again for your time and help....

This thread just saved me $155 and the pain of swapping out my 2 year old GDO unit with replacement. THANK YOU!

I had looked all over the net for answers but nothing until this thread which explains the same issues I was having and ironically all the steps I also had taken to date.

Final post of control board loose connections seems to have also been my issue now also solved...

Returning replacement unit in the morning still in the box....