Older Lift-Master opens and closes 6 inches only


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Old 01-11-14, 10:02 AM
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Older Lift-Master opens and closes 6 inches only

I have an older *Probably 10-15 years old" it was working fine 6 months ago, I usually only park in the garage when the weather is bad. Now when I use the remote, or the wall mount, it will travel up 6-10 inches, stop and go back down. if I am at the wall button I can stop it when it starts to go back down, hit it again, and it will travel another 6-10 up, then repeat back, again only 6-10, it is like it thinks the entire door is only a foot tall. I can repeat the open close all the way up to fully open, and all the way back to closed, but that is a waste of time, for now I have unhooked the power and the travel chain so I can just manually open and close the door,, any help would be great!
 
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Old 01-11-14, 11:23 AM
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Welcome to the forums. Your profile does not indicate where in the world you are, but I will assume that you have cold weather this time of year.

First, does your door open and close smoothly by hand, and will it stay in one spot if opened about half way? If not, the spring need adjusting.

Clean the door tracks. They should be free of oil or grime. Do oil the roller bearings, but not the roller itself. You can also oil the hinges between sections.

Finally, there should be adjustment screws on the opener. You can increase the up force to help the opener overcome the seasonal stiffness of the door.
 
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Old 01-11-14, 07:25 PM
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Sorry, hadn't gotten that far lol, I am in Denver Colorado, The door opens like a dream by hand, even when I unhook the door from the opener the opener only goes back and forth a few inches, I fiddled with what I assume is the force screws, two blue knobs on the back of it, one with an up arrow and one with a down arrow,,, it did not affect anything at all that I could find,
 
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Old 01-12-14, 08:33 PM
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liftmaster garage door only opens and closes a few inches

hi Folks
i have read all the posts but still cant get my liftmaster GDO working.

i replaced the opto transmitter but that did NOT change the behaviour

the white plastic gears show just a bit of wear and tear. I greased them a bit to make sure it was not causing too much resistance.

the door will move back and forth (sometime 1/2 inch , sometimes 1 foot. oddly enough, it seems to follow a sequence....every 3rd push of button, it seems ot move the most (about 1 foot)

the green led blinks 4 times

i did NOT replace the CUP that interrupts the light beam...but that just seems to be a simple piece of plastic. cant imagine that its not working. I can confirm that the fingers of the cup do go at least 1/2 way into the opto reader thing (thus breaking the beam i think)

of course I confirmed that the electric eye thing (safety device) is aligned and the door moves freely when i disconnect from the trolley.

I also cranked up the 2 knobs to exert max force in both directions

can someone please help ! thanks!
 
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Old 01-18-14, 12:05 AM
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Welcome to the forums.

I see you snuck a post in here on this thread

The four green flashes signifies a safety sensor out of alignment problem.
Does the light on the safety sensor look normal ? Is it flickering ?
 
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Old 01-18-14, 07:48 AM
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whoops. im a bit new to posting and threads , i probably should have started a new post huh?

if, by safety sensor... you mean the 2 units at ankle level by the door... yes they are aligned and there is a green led that is solid 'on' in both of them. in past, when they were not aligned... i dont think the motor would turn at all, not even a second.
now, the motor moves the trolley a fraction of an inch or sometimes a foot before reversing.
i did change the optical rpm sensor.. but nuthin'

im really scratching my head here .
 
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Old 01-18-14, 11:48 AM
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hi. thx for responding.. im not sure i replied in the right place.. just fyi
 
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Old 01-22-14, 06:51 PM
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i made a wrong assumption! i incorrectly thought the safety sensors were aligned and wasted a lot of time replacing stuff that didnt need replacing. thanks for the advice!!!, because si noticed the 'green led' was flickering. i adjusted the sensor a bit and light became a strong green. now door works fine

BTW - why does the system need an rpm sensor. isnt the little mechanism with start and stop contacts enough to know when to stop the motor ?
 
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Old 01-22-14, 09:28 PM
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The RPM sensor is always monitoring the motor when the opener is operating..... if the door should stop moving anywhere in it's travel...... not just the ends..... the motors stops.
 
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Old 01-23-14, 05:09 PM
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ahh. so its not bothering to count the # of revolutions to measure distance or anything like that , its just trying to know if the the door has physically stopped when it 'thinks' the door should be moving (ie when the system is applying power to the motor. is that right ?

isnt is possible for the system to be designed without that 'rube goldberg' rpm sensor... ie. simply measure the amount of current that the motor is pulling and if it spikes (ie i think a motor pulls a lot more current if it stalls ... kind of like the your car when when you hold the button down even after your window has rolled up) and if current spikes, then system can stop sending power to motor. this would require less moving parts. does that make sense ?
 
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Old 01-23-14, 06:02 PM
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You missed your calling You should be designing door operators.
 
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Old 01-27-14, 08:35 AM
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Clean RPM sensor with WD40 and blow out with compressed air, this fixed mine.
 
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Old 01-28-14, 01:08 PM
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i know this is crazy, down here in houston the mud bees build nests inside door openers. pull cover and make sure limits are ok. could be rpm sensor. easy to work on and get parts
 
 

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