Garage door opens /closes variably

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Old 11-02-18, 09:37 AM
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Garage door opens /closes variably

I have a liftmaster 1/2 hp chain drive. Lately it has been opening or closing a variable distance from the set limits. The door moves freely when disengaged and manually operated. It is balanced. When it stops in the semi-open/closed positions, the light does not flash indicating an obstruction and it does not reverse direction. I have played with the force settings, but no luck.
Any ideas? Thank you!
 

Last edited by boonjh; 11-02-18 at 09:38 AM. Reason: Typo
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Old 11-02-18, 09:52 AM
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Could you possibly have some spider webs that affect what the sensors see? I had a problem when a leaf was caught in a spider web and fluttered into the beam when the wind/outside air disturbed it.

Dick
 
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Old 11-02-18, 02:28 PM
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Check the limit switch closest to the head of the door. Sometimes there's just enough shift in the door header that the piece of stiffener material, across the top of the door, that the opener attaches to will make contact with the limit switch as it passes by going up or down.
 
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Old 11-02-18, 05:57 PM
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If I understand correctly, I have different setup. My limit switches (and corresponding adjustment dials) are on the actual motor assembly. I do not have any switches by the door header.
 
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Old 11-02-18, 06:15 PM
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Dick,

My sensors appear clean. Wouldn’t one expect the overhead lights to flash, when these sensors “detect” something?

Is it possible that the actual motor is meating resistance pehaps in a bushing / bearing, or is just petering out, rather than some obstruction that would activate the force limiters?
 
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Old 11-04-18, 04:04 AM
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If very well could be the plastic drive gear is failing or the bushing just under the drive sprocket is worn (does your chain look loose) the bushing wears out, the shaft tips forward which sometimes makes a gear loose contact with the limits.
 
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Old 12-24-18, 02:51 PM
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Thanks for your reply. The cog wheel / pulley looks good (I actually replaced it a few years ago). Something else I have noticed, is that it can get “stuck”, even when the door is disengaged from the trolley. It still puzzles me that when that happens, it does not reverse direction and the light does not flash as it would normally when encoutering an obstruction. I also tested capacitor, which was good.

I am stumped!
 
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Old 12-24-18, 02:57 PM
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I do not recall if I replaced the bushing when I replaced the plastic drive gear. I repkaced everyting that came in the “kit”. Is there an easy way to tell if bushing is warn, without dissembling the drive mechanism?
 
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Old 12-25-18, 04:08 AM
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usually the chain will loosen up, you can pull the cover off the opener and look on top of the planetary gear for black metal particles. That is a tell tale sign the bushing is worn. This is why I recommend buying the whole replacement gear assembly and not just the kit with just the gear and some lubricant
 
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Old 12-25-18, 10:57 AM
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All looks completely clean. no particles.The kit I used contained the following:
Sprocket drive shaft
Shaft housing
Main drive gear
Worm gear
Limit switch gear and clip
Lubricant
Replacement bushing, fittings, & pins
Instructions
 
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Old 12-26-18, 03:28 AM
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I went back and reread your original post, you stated "When it stops in the semi-open/closed positions, the light does not flash indicating an obstruction" ( is this on the up and down?) It sounds like to me the circuit board is loosing power, the door stops then power is immediately restored. I have seen this before and replacing the circuit board fixed it. When this happens the the light will immediately illuminate but not flash, just like it does when the unit is first plugged in.
 
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Old 12-26-18, 06:33 AM
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Thank you very much. That certainly sounds like it. Do you think it is worth replacing circuit board, or is this a good time to upgrade to belt drive? The unit is almost 15yrs old, otgerwise clean and good shape. Thanks again for you expetise!!
 
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Old 12-27-18, 03:26 AM
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15 years... I would upgrade, they are like any appliance. I recommend any Liftmaster/ Chamberlian belt drive opener. The new Liftmaster WLED are the best, most now come with built in wifi so you can run from your phone.
 
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