I have a LiftMaster 1255R. A few days ago I went out to go to work and the door wouldn't open. Just a small buzz from the opener. I took the cover off to see if I could see anything and I noticed that the drive gear was all chewed up. I ordered a kit and in the meantime just used the door the old fashioned way, manually.
I replaced the drive gear and worm gear, put it all back together, and now the door still doesn't work. It will move the door either up or down a few inches, then the exact opposite way til it reaches its full travel then it will bind.
If I turn the force all the way down, it will move a couple inches in one direction, then back to where it was.
I checked the limit adjustment, and it's as if the settings are completely being ignored. The door is opening or closing beyond the settings and actually bending the metal tabs on the limit switch.
Also, the directions that came with my gears said to have the door in the down position and put it back together the same way. When I do this, when I hit the button the door will try to go down (keep in mind it's already down) and instantly bind. Almost like the door is acting backwards of the way it should work.
I'm out of ideas, so if anyone can PLEASE help me. The only thing I can think of at this point is the circuit board, but that's $75 I don't want to spend if I don't have to.
I believe your opener is out of timing with the door. With the door down, loosen and remove the chain from the drive sprocket, then run the opener,watch the sprocket on top. ensure it is rotating clockwise (looking down from the top) when it stops, reinstall the chain
I did that, and when I do that it doesn't stop. It just continues moving in a clockwise direction til I hit the button. Even bends the tabs on the limit switch 90 degrees.
Or if I hit the button again, it moves in a counter-clockwise direction til I hit the button.
Originally Posted by ez4u2chere
I did that, and when I do that it doesn't stop. It just continues moving in a clockwise direction til I hit the button. Even bends the tabs on the limit switch 90 degrees.
Or if I hit the button again, it moves in a counter-clockwise direction til I hit the button.
Make sure all 3 wires are attached to the limits tabs (two stationary, one moves back and forth)
Did you unplug the opener when changing the gear kit? you may have shorted the circuit board
clean the limits tabs to ensure a good contact, some times they get corroded
I would have to guess a bad circuit board
Yes, I unplugged the opener prior to taking it apart. Also, the three connectors you speak of are hooked up and clean.
Is there anything else it could be other than the circuit board? I don't mind paying $75~ for a new board. It's paying $75 for a new board, then $20 for something else, then $20 for another something else, etc... that I'm afraid of.
Just wondering, is it possible to have the circuit board tested?
Originally Posted by ez4u2chere
Yes, I unplugged the opener prior to taking it apart. Also, the three connectors you speak of are hooked up and clean.
Is there anything else it could be other than the circuit board? I don't mind paying $75~ for a new board. It's paying $75 for a new board, then $20 for something else, then $20 for another something else, etc... that I'm afraid of.
I still think it is a circuit board, Liftmaster makes a tester, but finding a dealer who has one might be tough.
You could remove it and try it in another opener if you knew someone who has a similar model. you would need to find an opener with the serial number ending with 021-1F or 021-F stamped on the circuit board, it could be craftsman, liftmaster, chamberlian, DoIt best, Raynor, the list goes on
Read the last post in this thread, the guy had a similar problem and found a bad solder on the C/B
http://forum.doityourself.com/showthread.php?t=295348
You know, the more I look at the opener, the more I think it might be part of the RPM Sensor circuit. I did not realize that the gray wire that goes to the Center Limit Contact of the Limit switch is connected to Pin 3 of the RPM Sensor Circuit assembly.
It also seems as though at one time I saw the light on the back of the opener blink 5 times, which I think I read somewhere indicates something to do with the RPM sensor.
What are your thoughts on that?
I'm sure you know what I'm talking about, but just incase, here is a pic.
http://www.all-gates.com/ProdImages/aaaremotes_1776_5465403.jpg
Doorman, I just read that post.
The thing is, his was actually stopping when it reached the up position. Mine reaches the up position and keeps on going up. The limit contacts are being completely ignored up or down.
I guess it can't hurt to take the circuit board off and take a look, but I'd still like to know your thoughts on the RPM assembly.
Originally Posted by ez4u2chere
Doorman, I just read that post.
The thing is, his was actually stopping when it reached the up position. Mine reaches the up position and keeps on going up. The limit contacts are being completely ignored up or down.
I guess it can't hurt to take the circuit board off and take a look, but I'd still like to know your thoughts on the RPM assembly.
I guess it could be possible, but the only problem that I know of when an RPM sensor goes bad, is the motor will only run a little in the down direction then stop and return back, So in a sense the door would only travel about 6 inches and then go right back up to where it started. The RPM sensor , senses when a door hits an obstruction, the motor slows down, and the door is reversed for safety.
Originally Posted by Doorman2722
IThe RPM sensor , senses when a door hits an obstruction, the motor slows down, and the door is reversed for safety.
OK, well let me see if I can try to describe this correctly.
I just took EVERYTHING apart and gave it all a good cleaning. Circuit board and all. The board didn't look like it had lost any solder, and there were not signs/smells of it being burned.
I put everything back together and unhooked what I believe is called the helical gear (it's the small gear at the bottom of the sprocket/drive gear assembly that drives the limiter switch).
I then ran the opener without the chain hooked up and manually turned the limiter assembly. When the up/down contacts made contact with the center limit contact the opener stopped. This is how it is supposed to work.
I thought I had it all figured out, so I put the chain back on and again the door doesn't stop when the center contact makes contact with the up/down contacts. It acts just like they aren't there and keeps going up or down til it binds. Sometimes it binds so much that it's scarry being in the garage at the same time. The trolly was all bent up nearly touching the cealing.
What you said about the RPM assembly makes me beilieve that it IS the RPM assembly. The opener doesn't sense that there is an obstruction and keeps moving in the same direction up or down no matter what's in its way.
Does that make sense?
Oh yeah, one more thing, would the capcitor being hooked up wrong cause this? The manual I received with my drive gear shows a picture of it being wired up backwards of the way mine was wired up. Their picture shows the red wires on the left and the blue wires on the right. Mine was opposite when I took it apart. When I put it back together I hooked it up the same way I took it apart.
One reason I ask this is because the force settings seem backwards to me. When I first hooked it back up the door would only open a couple inches, then go back to beyond closed causing the binding. I increased the up force and nothing happened but it appeared to bind a little more when it went down. I then increased the down force and the door opened (then of course binded when it was up).
Originally Posted by ez4u2chere
Oh yeah, one more thing, would the capcitor being hooked up wrong cause this? The manual I received with my drive gear shows a picture of it being wired up backwards of the way mine was wired up. Their picture shows the red wires on the left and the blue wires on the right. Mine was opposite when I took it apart. When I put it back together I hooked it up the same way I took it apart.
One reason I ask this is because the force settings seem backwards to me. When I first hooked it back up the door would only open a couple inches, then go back to beyond closed causing the binding. I increased the up force and nothing happened but it appeared to bind a little more when it went down. I then increased the down force and the door opened (then of course binded when it was up).
the capacitor wiring doesn't matter.
By increasing the up /down force you are making the binding worse, That tells the opener to push harder in up/down direction. Or a higher setting makes the RPM sensor less sensitive requiring more resistance to reverse the door
Originally Posted by Doorman2722
By increasing the up /down force you are making the binding worse, That tells the opener to push harder in up/down direction. Or a higher setting makes the RPM sensor less sensitive requiring more resistance to reverse the door
I know.
But what I'm saying is that from a closed position the door would go up a few inches, reverse to beyond down, then stop. I increased the UP force and the same thing happened only it binded more.
To make the door go up I had to increase the DOWN force.
I believe this is exactly opposite of how it should be working.
Originally Posted by ez4u2chere
I know.
But what I'm saying is that from a closed position the door would go up a few inches, reverse to beyond down, then stop. I increased the UP force and the same thing happened only it binded more.
To make the door go up I had to increase the DOWN force.
I believe this is exactly opposite of how it should be working.
Well then go ahead and replace the RPM sensor because it is much cheaper than the main board ,and see what happens. But with the chain off, and it runs past the limits, I'm betting it's the main C/Board
Doorman, what do you think about this?
I received these troubleshooting steps today from liftmaster.
Jump starting a motor:
Unplug the motor.
Remove the motor cover.
Remove the logic board.
Locate the capacitor, it resembles a d sized battery. it has 4 wires, 2 red, 2 blue.
Make a jumper wire from insulated wire, it only needs to be 8 to 12 inches long.
Peel 1/2 inch of insulation from both ends of the jumper wire.
The power cord goes into the opener and end on a terminal block.
The terminal block has 3 wires, white, green and black. Each wire is secured with a screw.
Place one end of the jumper wire under the screw holding the black wire.
Plug the motor back in.
Touch the other end to the red or blue terminal on the capacitor.
If you touch red, the opener runs up.
If you touch blue, the opener runs down.
If the opener can run up and down without losing power, replace the logic board.
If the opener does not run, and you hear a short hum, replace the capacitor.
If the motor starts and stops, replace the wire harness.
If the motor runs and the gray contact pushes against the yellow or brown contact and does not stop, replace the low voltage wire harness.
As long as I keep the jumper connected to the red or blue, the door will continue to go up or down. If I take the jumper off the door will stop.
This to me rules out the logic board. It runs, so it's not the capcitor. The motor does not stop and start as long as I'm holding the jumper wire on the capcitor, so I guess that rules out the wire harness.
Now, the tricky part, the motor continues to run when the gray contact pushes against the yellow or brown (up/down of the limiter switch) which according to what they sent me says the low voltage wire harness is my problem. But doesn't the logic board sense the limit switch contacts? And step 3 says to disconnect the limit switch.
So I feel like I'm making progress, but I'm stumped just the same.
Can you shed some light?
And if you feel it is the low voltage wire harness, what exactly is it? I don't see any reference to it in my owners manual.
Ya got me, I have never heard of this before. You have surpassed the master in troubleshooting. I do not know what the low voltage wire harness is. I would guess it is the harness that plugs into the main board?
I'm 99.9% sure the problem is in the logic board.
When you ran the troubleshooting test, the board was disconnected. That means your opener is going to ignore any signal sent by the limit switch.
The opener is going to run when you make contact with the jumper.. and stop when you break that contact. The jumper by-passes the RPM sensor and the limit switch (among other things). The purpose of that test is to rule out a problem with the motor or capicitor.
In my many (too many) years of working on untold thousands of LM openers, I've never had to replace a low voltage wire harness.
Assuming you've correctly wired the limit switch, it's mechanically working and the contacts are clean... your logic board is bad. It's easy to mess up a board when you change out the gear... and you usually can't tell if it's bad by looking at it.
Well, I fixed it and I now feel like a total moron.
After running through the tests again last night, putting the jumper on the red or blue terminals of the capacitor, I realized the motor was only turning one way. hmmmm......
Well, here's the problem, the picture they sent me for my gears showed the red wires on one side of the capacitor and the blue wires on the other. That would have been all fine and dandy if my capacitor was mounted the same way the picture showed. Instead of having both red on one terminal of the capacitor, and both blue on the other, I had one red and one blue on one terminal, and one red and one blue on the other.
So, I hooked it up correctly and all is well.
Sorry for making you guys go on a wild goose chase due to my stupidity. haha
Also, I learned that the default settings for the limiter switch for a standard size door is 7 turns out from full close for the down, and 17 turns in from full open for the up.
On another note, my door is really loud. I always thought it was the opener, but after going through this escapade I realize that it is really the spring on my door. Is there any oil/lube that I can put on the rails and spring to make it a bit quieter?
You can lube your door with a light oil, lubricate the springs, bearings, hinges, rollers and the roller stems (where it goes through the barrel of the hinge) Do not use grease on your overhead door or track. You can grease the opener rail where the trolley slides back and forth
I know this is an ancient thread but since it helped me find my problem today I thought I would post. I replaced the 2.75 plastic chain drive gear today and put the opener back together. My door would move maybe a foot stop and return. I fiddled with it all day unplugging adjusting limit switches removing the chain and moving the door but all it accomplished was changing the where the door was at while it moved 12 inches. After reading this thread I went and looked at the green light on the back of the opener and it was flashing. I disconnected the RPM sensor wires and got the same result. So I figured it was an RPM circuit issue. The first thing I checked was the plastic crown shaped RPM interrupter. I push on it fairly hard and it snapped in maybe 1/16-1/8. I plugged in the opener and it worked. I re-adjusted the limit switches and all is well.
Thanks to everyone who posted to this thread. It gave me a little direction!
Welcome to the forums
Glad to hear this worked out for you
Sometimes when you put too much grease on the new gear, the grease will splatter onto the rpm sensor and cause a malfunction. And I too have been servicing LM openers, and every other opener,commercial and residential for many years and i am having a hard time believing that the capacitor wiring was the issue with this original post. I think someone put the cover back on before checking limits and really had things screwed up. A 41c4220A Gear and sprocket assembly replacement only takes about 15 minutes with plenty of experience, and with a little common sense you generally only need to adjust the limits from the original position by a fraction of an inch, and I've never had to disconnect the capacitor during this process.(you'd better unplug the machine though)
$135.00 total and 45 minutes later after a good door service as well, will save a lot of people a lot of headaches, plus if something directly related goes wrong afterwards, a good service company would(or at least should) handle it without charge under a 30 day workmanship warranty.
Thank goodness for this thread. I had replaced the gears on my liftmaster door opener and everything seemed to be working backwards. I don't even remember touching the capacitor but sure enough after reading through this thread, I checked the capacitor connections and I had it wired wrong. I was going bananas trying to figure out how the damn safety stuff was working backwards (i.e. when you broke the beam with the door going up, the door reversed and CLOSED. If you broke the beam with the door going down it didn't stop). Anyway, with the capacitor miss wired the motor was running in the opposite direction of what it was supposed to be doing. When the controller thought the door was going up, it was going down, etc. I have been working on this stupid thing for weeks. Grrrrrrr.
So I replaced the gears and got everything working. I was doing great. Really high on myself. Then I got ahead of myself and made a bad mistake.
When I finished installing everything I was so happy that it was all working that I did not properly ensure the next push of the garage door would send it up. So with my door in the down position the motor sent it down.
It locked up. While watching there was even a little smoke before I disconnected the power cord.
Now one side of the chain is an a lot of tension (looks unsafe), and the other side is all slack.
Thoughts? I turned the power down to low, so I'm hoping that saved permanent damage. A friend told me I'd probably have to replace everything....
Really hoping there's a solution here. If I press the button again, shouldn't it go in reverse and go up??
As seen from the posting below, jump starting a motor, I too am having trouble with my chamberlain model 5100 door opener. It was acting up for a few weeks, then it went haywire. Upon opening it I noticed the plastic drive gear was shreaded and shavings lying below it. I replaced the gear ( for $4.90 ) and now before re-installing it, have tried to operate it. It runs for one second in one direction, then reverses and will run forever unless the limit switches are reached. I'm assuming the shreaded gear is a result of , and NOT the real problem. I took advise from below and jumpered the black wire to the red capacitor wire, and the motor ran continuously. Jumpered it to the blue wire, the motor ran continuously in the other direction. Does this mean for sure it is the logic board that is bad ?? Where can I get the least expensive board ?
New / used ?
When it comes to gear replacements, I've found using the entire gear and sprocket kits does a better job. replace both gears, use new bushings in metal bracket and re shim motor to metal bracket. it's not that much more for the complete kit. 41c4220a found here
if you forget to put the very small gear that drives the limit switch assembly at the bottom, then the motor/trolley will run until it jambs against something and locks. i usually take channel locks on the short side of motor shaft until it frees itself.
OKAY I am stumped..........I have replaced the logic board. As I check for continuity on #'s 1 to 2, 1 to 3 and 2 to 3, they ALL have continuity. When I hit the remote, it will run for a short while in one direction, then reverse stop at the limit switch. If I continue to attempt to remotely operate it, the motor goes less than one revolution, and stops, as it is still at the limit switch post. ( Wrong way of desired operation ) Then, if I jump #'s 1 and 2 together and HOLD them together, the closer will work properly. IF I release the jumpers before the door has cycled completely to the other limit switch, the motor will stop, and reverse itself until it reaches original starting point, the limit contact. Thus, IF I hook the unit up, I will be able to completely close the door by holding down the indoor switch. The door will then open and operate by pushing the remote / OR / indoor mounted garage switch. After backing the car out, and attempting to close the door by remote, it does not work. The motor will again turn less than one RPM then quit and blink the light. Also, the blinking green light on the back would blink sometimes 4 times, but mostly only twice. I can only close the door by holding the garage mounted opener button until the door is fully closed. Any ideas ??
Well, well, well,...........after going and buying a new garage door opener, as I was installing it I noticed the lights that I had taped together instead of installing them at the lower door area on each side of the door ( yes the safety lights ) I had them taped together sitting in a bucket on top of the opener. Well, I noticed they had come apart probably from all the vibrations over the years. So, with no signal , the door continued to try reverse itself. So, lesson learned.............CHECK everything BEFORE replacing anything!! I am humbled to say the least!!
Why would you not install the sensors? That's a very important safety feature.
Tags: problem, liftmaster, limit switch, logic board, circuit board, door would, drive gear, Originally Posted, wire harness, back together, Originally Posted ez4u2chere, Posted ez4u2chere, this thread
