Garage Door opener is tripping its circuit breaker

Thread Starter

wayneh

Joined Sep 9, 2010
16,102
My LiftMaster garage door opener is 27 years old. I've replaced the drive gears once but otherwise it's been quite reliable. It's nominally 1/3 HP.

Recently it has started blowing its breaker intermittently. I think the rate is increasing. I removed the ~100W lightbulb but the trips continue. There are a few low wattage lights on the same breaker, including an outdoor "gaslight".

I once was looking at the lift when I hit the button, and saw a small flash as it tripped. At least once when it had tripped, I had to unplug the unit in order to reset the breaker. It worked normally when plugged back in.

I haven't opened it up yet but I'm just posting to see if anyone has previous experience that might explain all this. How about the limit settings? It occurs to me that it always fails fully closed.
 

MaxHeadRoom

Joined Jul 18, 2013
19,014
Have you adjusted the down/up limit, two adjustments on the motor unit itself.
You could reduce the down setting to see if any results, the other issue could be the start capacitor as a long shot.
Max.
 

jpanhalt

Joined Jan 18, 2008
7,876
Have you tried "grease?" Not the spray stuff used for cooking, real grease and mineral oil.

Also, if your door is coil assisted, might check that the coils aren't broken. That is probably an unlikely cause for something that developed over time.
 

Hymie

Joined Mar 30, 2018
708
Are you sure that the breaker is tripping due to an over-current event; and not earth leakage/ground fault?
 

Thread Starter

wayneh

Joined Sep 9, 2010
16,102
Are you sure that the breaker is tripping due to an over-current event; and not earth leakage/ground fault?
The breaker is also 27 years old and back then, the breakers did not have those fancy capabilities. So yeah, I'm sure of that one. I do wish I had a measure of the current going outdoors to that gaslight. I don't suspect any problem (it's working normally) but I'd like to take it off the list of possibilities. The arc I observed certainly draws my attention to the lift unit.
 

Thread Starter

wayneh

Joined Sep 9, 2010
16,102
Have you adjusted the down/up limit, two adjustments on the motor unit itself.
You could reduce the down setting to see if any results, the other issue could be the start capacitor as a long shot.
Max.
I have not, but I think that may be the first thing I do next. I did install a new gasket on the bottom of the door last year and it's a lot beefier than the old one. Everything worked fine then so I never made an adjustment.
 

Thread Starter

wayneh

Joined Sep 9, 2010
16,102
Have you tried "grease?" Not the spray stuff used for cooking, real grease and mineral oil.
Not yet, no. It seems to move smoothly but I haven't examined it closely yet.
Also, if your door is coil assisted, might check that the coils aren't broken. That is probably an unlikely cause for something that developed over time.
It's definitely coil-assisted but they're fine and the door is still working maybe 90% of the time. I can easily lift the door by hand if the power is out.
 

MaxHeadRoom

Joined Jul 18, 2013
19,014
This is why the suggestion on adjusting the down pressure setting, I had to adjust mine recently as it would not go down, it would move a foot and go back up.
Max.
 

jpanhalt

Joined Jan 18, 2008
7,876
I can easily lift the door by hand if the power is out.
That's a key observation. My home in Parma Heights (Cleveland) has solid, wood paneled doors (circa 1950). Could never lift them without the spring assist.

I would look for binding, clean and re-lubricate. Guide rails and drive. Don't forget the motor bushings too. Good to do both regardless of the reason for the problem. It is also possible the circuit breaker has gone bad and trips at too low a current.
 

Thread Starter

wayneh

Joined Sep 9, 2010
16,102
Turns out the limit adjustment changes the force, not the position. Both the up and down force knobs were set to the line between low and normal. There’s also a high setting. I turned the down setting a little farther in the low direction. Nothing else obvious but I didn’t open it up yet.
 
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