Liftmaster 3900 Troubles

[Teken]

First off, I wanted to thank all the members for their past threads on the topic at hand. I have checked a few things to ensure the basics havent been missed prior to posting.

PROBLEM: Its -38 'C out where I am at, so alot of this takes 99999999 longer to do and confirm! I have been up and down this ladder, and feel like a well used toilet seat!!!

- First things I wanted to confirm with you all: This unit just came with a ugly green single push button. As far as I can tell there is no indicators or marks as to which of the wire goes where in this push button box. That being the WHT / RED, and the WHT wire, which then goes to the operator unit.

Please confirm that the placement of the wire on this switch is not critical.

- Next, the belt tension monitor: In a few pictures posted on this site the device appears to be much further than the indicated distance in the manual which states it should be 18 mm from the wall while tensioned from the cable. I will confirm the distance of the cable from the wall with respect to the monitor to verify it isnt being activated while closing.

As both sides of the cables appear to be tight, and firm with no slop or binding.

( Right now I can't honestly say if the micro switch is being activated while it goes down. But, have no problem going up there 999999999 times at this point to make it freaking work!!!

- Sensing Eye: Currently I have all four wires plugged into their respective plugs. In a previous thread it was indicated that the two pairs are to be joined prior to entering the two plugs. Please confirm for me if the way I have installed it is a problem, if so I will parallel them prior to installing them into each plug.

The sensors on both sides are lit solid, and prior testing shows that the sensor does work as it does make the operator stop and reverse the door when the beam is broken. The green LED also does go out, when you break the beam.

- How does one reset this device as if it came out of the box? There is no mention of this on any site. I want to ensure that this device has not been improperly set, which is giving me all the grief I am having now.

Case in point the device will not remember the upper limit when set multiple times! The blasted unit wont even let me program or teach it the lower limit as it constantly stops at the top where the track starts to bend.

- In one other site it mentioned to just teach the blasted box the force limits first, so it knows how much force to use to raise and lower the door.

My problem is not raising the door, but lowering the door. This is a brand new house only 4 months old. The door is well balanced and stops at any level. The part that always confused me is when people state a ten year old child should be able to raise and lower the door with little effort.

I have been around long enough to tell you I have yet to see a single door of 16 X 8 being raised or lowered from such a person regardless of tension.

The door manually goes up with some effort, and does go down with some effort, and does not bind, shudder, or any other odd sounds.

So, I need some help as to what is stopping this door from being programmed for its lower limit, the force limit, and confirmation on the above Q's.

Sorry for the length of this thread, but its really late, and I have been out side in this insane cold for 8 hours and just cant think straight anymore.

As a side fix, what I have done is program this device is to raise just before the bend in the tracks, and this seems to open and close the door once!! Opening and closing the door multiple times just results on the door hanging up when it has to come down.

So, its either the force travel that's dead wrong. Which I cant teach it since it wont complete the 3 passes of up and down. And if I could simply reset this freaking box to factory I would know if its simply a programming issue!!


Anyways, many thanks to all previous member for all the good info as it helped me just confirm the install step by step.

BTW: The collar bolts are all well tensioned and no slippage is present. I confirmed this by marking the collar, and bar.

Also, can someone please let me know where, or who has the best price on the auto lock, remote light? As I have found all the other parts I need from another vendor, but he doest carry the other two parts needed.

Regards

Teken . . .

 

[Teken]

Also, I have unplugged this unit for 24 hours to see if it would reset to factory. It doesnt, and just remembers the last setting I had entered before. But like I said it wont learn the new settings no matter how many times I try.

I don't have a remote light as well, so can't tell you any info on that. The unit does flash the trouble LED indicating one of several things is present or wrong.

9 flashes indicating the cable tension monitor

12 flashes, no freaking clue, as it doesnt say anywhere? Some where on this site someone said it could be a logic board, or rpm sensor.

Regards

EVIL Teken . . .

 

[nova65ss]

The wires for the wall control should not make a difference which way they go, usually they are numbered number 1 will go on the red terminal. SO when you open the door by hand when it gets to the top does it shoot up pretty fast and really hard to pull down there? Is the cable slack when it is all the way up?

 

[Teken]

The door will remain up at any position, and it does take some effort to push it all the way to the top. Please keep in mind I am also only 5'6" so im on my tippy toes!

With respect to the cable, could you please discribe what, where, I should be looking at to confirm the cable tension.

As always, I have appreciated your feed-back and support.

Regards

Teken . . .

 

[jimmie jam]

i feel your pain. that's why i paid $1950 to have three 3800's installed with the remote lights, digital operators, remotes, auto lock and wireless remotes at the exterior of the doors. it took 3 guys 12 hours to install three doors and operators (and get them to work right). sometimes these installs are better done by seasoned professionals. it's not knowing or learning what to do. it's knowing what to do NEXT, like the situation you're in. i'm sure someone will help you here. good luck. BTW, the doors were another $4000 in addition to the 3800's.

 

[nova65ss]

The cable tension monitor needs to stay open I would watch it as it goes up and down and see when it closes and figure out why.

 

[pattenp]

Quote: "The door manually goes up with some effort, and does go down with some effort, and does not bind, shudder, or any other odd sounds."

This does not sound quite right. At the half open level your door should remain open, above halfway it should raise on its own from spring tension, below halfway it should close from its own weight. If you have to push it up to get it open all the way or pull down on it all the way to get it to close then you have a balance problem or some binding going on in the tracks.

 

[pattenp]

Quote: "- Next, the belt tension monitor: In a few pictures posted on this site the device appears to be much further than the indicated distance in the manual which states it should be 18 mm from the wall while tensioned from the cable. I will confirm the distance of the cable from the wall with respect to the monitor to verify it isnt being activated while closing."

Your description of the mounting of the Tension Monitor is not clear. The distance from the cable to the mounting surface on which the Tension Monitor is attached should be 3/4" or 18mm minimum. The main thing is the cable needs to have tention through its entire travel to keep the roller in its outward position.

 

[nova65ss]

Quote: "The door manually goes up with some effort, and does go down with some effort, and does not bind, shudder, or any other odd sounds."

This does not sound quite right. At the half open level your door should remain open, above halfway it should raise on its own from spring tension, below halfway it should close from its own weight. If you have to push it up to get it open all the way or pull down on it all the way to get it to close then you have a balance problem or some binding going on in the tracks.

The door should not raise on its own at half way it really should just stay where it is. On the way down it should not fall from half way either. A properly balanced door should pretty much stay where it is no matter where it is.

 

[pattenp]

The door should not raise on its own at half way it really should just stay where it is. On the way down it should not fall from half way either. A properly balanced door should pretty much stay where it is no matter where it is.

In the perfect world that would be balanced. My understanding of a balanced door is when above halfway the door will start to lift on its own, below halfway it will start to close on its own. It should be balanced to stay open at halfway. I have had doors professionally installed and they all have positive lift in the top third of travel and negative lift in the bottom third of travel. I'm not aware of perfectly balanced doors that will stay open in any point of travel, at least I haven't seen any. The only ones I've seen stay where you lift them are the ones where the rollers have so much friction on them or the tracks are out of whack they'll stay open at any level. But that's not to say that there aren't any perfectly balanced doors out there.

 

[Teken]

The cable tension monitor needs to stay open I would watch it as it goes up and down and see when it closes and figure out why.

This is obviously a serious problem right freaking now!! So, guess what?? I am about 40 minutes out side of the city on the way to a family gathering. What do I get on my cell phone?

A SMS message indicating that my garage door is wide open. Next, with in 20 seconds of getting the text message from my alarm system. I am speaking to the alarm monitoring station which indicates not only is the door ajar, but they believe someone is in my freaking house!!!

After doing some checks and having the police on site all the while I'm still 40 minutes away, the house is secure.

First Q I have to ask for confirmation is this. How on Gods green earth did this freaking thing open my door, if noone has pressed the button?? I was told this can't happen.

Regardless, you would think during the two freaking days I have working on this stupid thing that it would have tried to open up just once by itself!!

Murphy's Law . . . If **** is going to happen it will happen when you're not around to do a damned thing about it!! Geeeeeeeeeeeese

Anyways lets get some facts in here so you all have more info to go on.

- Several times I was able to make this door go straight up and down and have to stop in ANY position when I was teaching it where the upper limit was.

This is why I believe two problems exist right now. One being the cable monitor is not tensioned correctly and as the door is going down it is tripping the micro switch.

Second, the force limit has not been learnt by this device, hence why it continues to fault out. The door never goes through the whole 3 up's and downs as it is suppose to because it always stops at the very begining of the closing event.

With respect to the balance thing: As indicated the door will stay stationary in any position regardless of height.

In the ideal world I believe a little help in raising and closing as the one member has stated is more practical, regardless of right or wrong.

I don't know for sure as I am not a pro or a garage expert and freely admit this.

But, the bottom line is this: I can't have this blasted thing open my door while I am away no matter what. I know alot of you can relate, we all have too much invested in our tools, toys, etc to loose it because of a stupid fault.

As the other member has also stated, sometimes calling in the pro's is the only recourse. I will seriously consider this avenue if I am unable to get this thing to operate in the next 48 hours.

If you guys could please find out the following things for me that would be most helpful.

- Can the operator open the door with out any human intervention at any time? If so, is it a sensor, board, etc causing this?

- How does one reset this device to factory out of the box specs? I want to make sure its starting from scratch. In the field where I am in its called a scratch install, for others its either a low format, full reboot, or full init.

Don't care what its called, just want to know how to do it so I know I am starting from new, no B.S. mixed programming etc getting in my way!!

As always I appreciate the help, feed-back, and assistance from one and all.

Regards

Teken

 

[StumpXJ]

Ok, deep breath.

I had similar problems as you are describing, and if I had any hair I would have been pulling it out. But you can beat this.
My door 'balances' similar to what you describe, it sounds normal to me. My door is also 18 foot wide, I am assuming yours is also a large door? Not that it matter much if its balanced.
Anyways lets get some facts in here so you all have more info to go on.

- Several times I was able to make this door go straight up and down and have to stop in ANY position when I was teaching it where the upper limit was.

I did this as well.

This is why I believe two problems exist right now. One being the cable monitor is not tensioned correctly and as the door is going down it is tripping the micro switch.

This is a super simple device, it *should* be obvious as to how it needs to work in order for the door to open/close properly. Forget the numbers they give you. Just mount it in a way that it works as it should. Also, while you are teahcing the opener what you need to teach, simply remove the tension monitor from system, but still leave it hooked up as it thinks it should be. (wedge something between the arm to keep it open). This will eliminate that potential problem for good until you get the thing programmed. Take note, OSHA would not aprove, just use your head here. It aint rocket surgery.

Second, the force limit has not been learnt by this device, hence why it continues to fault out. The door never goes through the whole 3 up's and downs as it is suppose to because it always stops at the very begining of the closing event.

This is probably the most frusterating thing with this opener. I had the same troubles. If the 'force' is not great enough to open the damn door, how the hell is it supposed to learn the limits properly right? Not sure waht they were thinking, but its backwards. They should have set it from the factory at its strongest level, then once the lmits are learned, you could tone it down a little. But this is not how it works, as you have found out.

I had to set my force first to get it to set the limits later. Sounds catch 22, since it doesnt know the limits, but it will work. I had to actually "help" the door a little in the initial closing, as it would fault otherwise since it didnt have enough force, once I did this (took a couple tries), every damn thing else fell into place with the llmit settings.

Why your door opened for no reason, I cant help you on that one. possible something to do with the tension monitor moved while you were gone.


With respect to the balance thing: As indicated the door will stay stationary in any position regardless of height.

In the ideal world I believe a little help in raising and closing as the one member has stated is more practical, regardless of right or wrong.

I don't know for sure as I am not a pro or a garage expert and freely admit this.

But, the bottom line is this: I can't have this blasted thing open my door while I am away no matter what. I know alot of you can relate, we all have too much invested in our tools, toys, etc to loose it because of a stupid fault.

As the other member has also stated, sometimes calling in the pro's is the only recourse. I will seriously consider this avenue if I am unable to get this thing to operate in the next 48 hours.

If you guys could please find out the following things for me that would be most helpful.

- Can the operator open the door with out any human intervention at any time? If so, is it a sensor, board, etc causing this?

I dont understand this question honestly.

- How does one reset this device to factory out of the box specs? I want to make sure its starting from scratch. In the field where I am in its called a scratch install, for others its either a low format, full reboot, or full init.


Don't care what its called, just want to know how to do it so I know I am starting from new, no B.S. mixed programming etc getting in my way!!

I honestly dont remember, but doesnt it have something in the owners manual about resetting the system? Not much help there...

As always I appreciate the help, feed-back, and assistance from one and all.

Regards

Teken

Dont give up on it, it kicked my *** for a few hours too, but it works like a champ now and is a SWEET opener when working properly. Good luck.

 

[Teken]

StumpXJ,

I am much calmer now then before that's for sure! I have read a few of your threads about the similar problem I am having. So, allot of the answers I applied came from you, and others.

So many thanks . . .

I did in fact follow your tip about teaching the unit the force required to move the door which is a 16 x 9 insulated R-12 door.

Where I am at: I have corrected a few installation problems which I caused not knowing, and others just for the sake of doing it.

1. Wired the safety eye in parallel prior to inserting both pins into their respective ports.

2. I had a rope in the middle of the door hinge to assist me to pull the door down, hoping if I could jump down from the ladder fast enough while it was in the down mode for learning I could help the unit do its thing.

While this was great and all, sometimes the length of rope would just catch the sensor eye and make it trip. I have since removed the rope to ensure its not just another small thing getting in my way.

3. I did remove and cheat the wire tension monitor with a screw driver and left it on the ground in the interim just to make sure it wasn't the placement of the unit which was giving me all this grief. Taking it down hasn't made a difference but at least I know its not a problem either.

4. I have varified the idiot switch is wired correctly, just in case there is a difference to the operator, there isn't !

5. I have set the upper limit so the door hangs just before the turn of the rails. As this seems to be one of the major problems here. The blasted door will not reverse (go down) if its completely parallel.

What I find strange is that when you're in the upper limit adjustment routine. I can push the up and down button and raise and lower this door from any point in its travel path.

So its not a question if the unit can or cant move the door from a particular point. As I stated before I believe its because the force limit routine is not complete, and is not learnt!!

While its simple to say *Well billy bob joe, go and make it learn it!*

The unit will NOT learn the routine. It will go up once, then on the reverse of going down, it will stop right at the curve of the rail, or often times will not move from the parallel point.

Now, I know this may sound funny to some of you but I will say this for the sake of saying it, just because well . . . I always speak my mind!!!

I believe the primary reason is that when the door was installed it was a beautiful 20'C tension was set all fine and dandy. So what ever tension, force, what ever you call it was fine in that temperature / environment.

Now, that it's a insane -36'c out here, the freaking springs are tensioned 1 to 2 x its working range.

Everything I own or have always breaks or wears out 9999999999 faster in this climate, that's why if I find something that works in our winters I buy it for life and recommend it to all my friends and family.

Right now, I have settled for having the door partially lower than it max open position, only so I can use the damned thing.

My previous door opener has since quit, and states:

You don't get fed, sexx, or anything else, if I continue being the door opener!!

So, you'all understand where I am coming from???

As always many thanks and any feed-back about resetting the unit to factory would be great.

Also setting up the force limit, and the upper range thing. OK, im beat and I need to work on something that will work out positive for me this evening.

BTW: Happy New Years to all of you great folks !!!

Teken

 

[homeworkman]

Hello,

I have the exact same problem as you described.

My opener is a Sears Craftsman Model 139.18405D, I hear they are re-branded Chamberlain Liftmaster units. I've read the liftmaster manuals online as an alternative and it uses the exact same fonts and exact same pictures in their manuals!

---
It too, will refuse to program the travel limits for me as well. When I followed the manual to program the up limit, then press the remote button to set it and then the door begins to go down and I press the GDO unit button to stop the door and to toggle the down position on the GDO unit.

But when I press the remote button the door never opens back up, and the unit just flashes its lightbulbs 10 times. So basically I never make past Step 6 of the "program the travel limits" section of the manual.

It only remembers the old settings and never learns my new settings I can't attempt to make it "learn". As the unit refuses to.

---
I have tried the Forces learning first before the travel limit programing as suggested, but that did not go so well as when I attempted it... The door goes down and as it closes I can see the rail flexing and it looks as if it keeps going and trying to close some more with more force being applied. Then it stops and stays closed with the rail visibly flexed.

I press the remote button and the door opens, to attempt to complete the force learning cycle. When I press the remote button the final time to close the door once again. As it closes it uses such force again to close, then the door will reverse to open back up. It never manages to stay closed.

So it essentially fails Step 3 of "Setting the force" in the manual.
---


Normally when "using the old settings".

2 things.

- If the garage door is at a closed position first: When I press the remote button to open the garage door, it looks as if as it is trying to close some more before the door opens up.

- If the garage door is at an open position first: When I press the remote button to close the door, it will close, I see the rail flex closing with such force until it starts to reverse and open again.


While GDO unit is idle, the little diagnostic LED, blinks 9 times, then pauses 10-15 seconds and blinks 9 times again. It keeps going like this forever.

I heard that the 9 blinks of the diagnostic LED means a cable tension monitor problem? There is no mention of this in the GDO manual, as it only lists diagnostic LED flashes up to 5 flashes.

I have a Belt driven unit.

I have left the unit unplugged for about a month and I was using the door manually as I did not have any time to troubleshoot for the time being prior. but still remembers the old programming when I plugged it back in to try again. (unbelievable!)

Also the Door is perfect, no sticking, no binding, balanced, etc..

The Seneor eyes are also good, solid lit green, etc. Sensors tested good when I purposely "trip" it while the door was closing.

Also the force test works well i.e. placing a recycling box on the floor and letting the door close on it, so that is okay.
---

This unit has only the black and purple buttons to program limits, there are no adjustments knobs to finely tune any forces or limits as in their prior older models as the manufacturers made it look different now.

I also want to know how to reset this GDO unit to factory default "out of box" settings. Because yes, when I first got the unit brand new, I WAS able to program the travel limits at one time! It makes it seem like once you put in your limits programming and you "F**k up" it stays remembered for life kind of like and you are Sh*t out of luck if you attempt to re-program it again.

There's gotta be some internal CMOS battery or jumpers inside the unit's logic board I can remove/reset??

The GDO manual makes no mention on what to do next if you fail on the programming steps, specifically on the problems I am encountering currently. It is unheard of. This issue was extremely difficult to search online as I have been searching for months on end about this particular issue.

But when I ran to into Teken's issue I got excited to know that I found someone else experiencing the exact same described issue!

So finally, I just want to know how to "factory default" the entire GDO unit.

Thanks for reading and any suggestions provided would be greatly appreciated.


Alvin

 

[Teken]

Hello,

I have the exact same problem as you described.

My opener is a Sears Craftsman Model 139.18405D, I hear they are re-branded Chamberlain Liftmaster units. I've read the liftmaster manuals online as an alternative and it uses the exact same fonts and exact same pictures in their manuals!

Please confirm that your door opener is a jack shaft styled unit. As there are no belts in this unit, that you mention.

---

It too, will refuse to program the travel limits for me as well. When I followed the manual to program the up limit, then press the remote button to set it and then the door begins to go down and I press the GDO unit button to stop the door and to toggle the down position on the GDO unit.

But when I press the remote button the door never opens back up, and the unit just flashes its lightbulbs 10 times. So basically I never make past Step 6 of the "program the travel limits" section of the manual.

It only remembers the old settings and never learns my new settings I can't attempt to make it "learn". As the unit refuses to.

The reason the unit will not learn is because the main board has detected a over limit drive situation in the down position

I have tried the Forces learning first before the travel limit programing as suggested, but that did not go so well as when I attempted it... The door goes down and as it closes I can see the rail flexing and it looks as if it keeps going and trying to close some more with more force being applied. Then it stops and stays closed with the rail visibly flexed.

This validates my answer above, this problem also happend to me as well. What you need to do is teach the unit to stop the door 1-2" from the floor. The reason you're going to do this is because of what you have observed. The unit is trying to learn the force limit all the while they door is being forced past its safe travel limit.

Please ensure you set the door 1-2" from the floor first, this may sound retarded, but it will make sense in a few moments. This will also protect you, the door, and the door opener from breaking.

I press the remote button and the door opens, to attempt to complete the force learning cycle. When I press the remote button the final time to close the door once again. As it closes it uses such force again to close, then the door will reverse to open back up. It never manages to stay closed.

Please read the reply above.

So it essentially fails Step 3 of "Setting the force" in the manual.

You're partially correct here. The primary problem is that the door is set at the down position TOO FAR, you must ensure you program the door to stop 1-2" before the door contacts the floor. The reason being is that you have observed the over drive of the unit. This will happen again, and it will either do one of of two things. You will either see that the 1' gap disappears, or it wont. If it disappears you're ready to move on to the next step. If you still see another 1" of space / gap please adjust the up and down of the door so as you obtain that distance. This is critical because this is stopping you from doing the other portions of the learn procedures

Normally when "using the old settings".

2 things.

- If the garage door is at a closed position first: When I press the remote button to open the garage door, it looks as if as it is trying to close some more before the door opens up.

- If the garage door is at an open position first: When I press the remote button to close the door, it will close, I see the rail flex closing with such force until it starts to reverse and open again.


While GDO unit is idle, the little diagnostic LED, blinks 9 times, then pauses 10-15 seconds and blinks 9 times again. It keeps going like this forever.

I heard that the 9 blinks of the diagnostic LED means a cable tension monitor problem?

I had the exact same problem. It was infact the door monitor it was positioned too close not allowing the proper cable gap / tension on the micro switch. If this portion is not down correctly as well all other steps are for not. For the interim to remove this device from the problem equation, please remove it off the wall, and insert a screw driver so as it keep the micro switch in the open position. This will allow you to proceed with the other portions of programming with out further stress.

I have a Belt driven unit.

Once again please confirm that your unit is indeed a jack shaft unit, as there are no belts in this model. Regardless the programming is the same so no loss there.

I have left the unit unplugged for about a month and I was using the door manually as I did not have any time to troubleshoot for the time being prior. but still remembers the old programming when I plugged it back in to try again. (unbelievable!)

That is correct this unit has a EEPROM which will retain all user settings regardless of power failure status. The unit can only be *reprogrammed*

Also the Door is perfect, no sticking, no binding, balanced, etc..

The Seneor eyes are also good, solid lit green, etc. Sensors tested good when I purposely "trip" it while the door was closing.

Also the force test works well i.e. placing a recycling box on the floor and letting the door close on it, so that is okay.

Thank you for confirming those two things are indeed correct and properly adjusted. I had the same experience as you, it is not the preset saftey reversal force that is wrong. It is your door travel limit is set to close the door too far. Please ensure you follow my steps above.

I also want to know how to reset this GDO unit to factory default "out of box" settings. Because yes, when I first got the unit brand new, I WAS able to program the travel limits at one time! It makes it seem like once you put in your limits programming and you "F**k up" it stays remembered for life kind of like and you are Sh*t out of luck if you attempt to re-program it again.

There's gotta be some internal CMOS battery or jumpers inside the unit's logic board I can remove/reset??

Plain and simple, you can't! Your observations as to *out of the box* is correct. That's why I recommend to all new owners who ever read this thread . . . Once your install is complete, only teach the unit the remotes. Do not teach the unit any force travel limits etc. It will **** you up, and you will have to follow all the steps here, as to what I out line to do. Allot of this is back wards in terms of common sense, or how to trouble shoot, but I assure you it does work, and it saved my bacon, and all the hairs on my head doing this in the opposite fashion from the manual. There is no factory reset, init, reboot, or scratch install. The units main board needs to be reset at the factory with a tool, or the board needs to be replaced.

The GDO manual makes no mention on what to do next if you fail on the programming steps, specifically on the problems I am encountering currently. It is unheard of. This issue was extremely difficult to search online as I have been searching for months on end about this particular issue.

But when I ran to into Teken's issue I got excited to know that I found someone else experiencing the exact same described issue!

So finally, I just want to know how to "factory default" the entire GDO unit.

Thanks for reading and any suggestions provided would be greatly appreciated.


Alvin

Alvin, welcome to the GJ forums! I too only got here because I used Google to find some answers to my problem. For clarification for others who may not know. The 3900, and the 3800 are the same unit. The 3900 is the commercial unit minus all the extra's that the residential unit comes with. Otherwise its the same unit. Please read my reply regarding the factory reset. Should you have further questions please do reply back. This took me 4 hours to figure out on the 999999999999 attempt at -40'C below, that makes trouble shooting and going up and down a ladder extremely hard on a persons body and electronics.

 

[homeworkman]

Hello Teken,

Thank you so much for your suggestions, I really appreciate your time so much like you wouldn't believe.

I do not have a Jackshaft styled unit, what I have is a trolley styled unit with belt drive. Meaning I do not have that motor unit which mounts beside the garage door and there are no cable tension monitor devices.

(Yes I've looked in the Liftmaster 3900 series manual online just to compare with my Sears Craftsman Model 139.18405D, and it is way different in the method which is used to operate the door, but the programming method used is verbatim though).

Unfortunately I could get the darn GDO unit to "teach" it to close at 1" or 2" off the floor.

I went straight to "programming the forces" first by letting the door close on a 2x4 laid flat on the floor. But it does too much closing force and the door reverses on its own (while still during the forces programming stage). So it could not learn the forces properly in this case.

Normally when I attempt to program the forces (without the 2x4 laid flat that is) the door actually stays closed, but the rail is way too flexed. But it still fails the forces programming either way.

I am not sure I am doing something incorrectly here?

When I tried it just for the hell of it, (even though I did it dozens of times prior) I could never get the unit to learn the travel limit to close the door 1 or 2 inches above the floor (Gap). As soon as I press the remote button to learn the down limit with a 2 inch gap between the door an the floor. The unit lightbulbs flashes 10 times and fails programming the travel limits everytime.

I am tempted to disassemble the unit just to access the logic board, just to see if there are anything "hidden" such as some resetting buttons to purge all programming from the EEPROM??? I don't know maybe I am just talking crazy wishful thinking on that part

I am beginning to believe I am running out of luck.

I dunno if I can warranty the unit

Thanks very very much again.

Alvin

 

[Teken]

You can not make the door stop any where before the door hits the floor?

I would like you to try this for me and tell me what happens, OK. I want you to make the door go up, when the door is in the middle of raising the door, press on the remote again. The door should stop at mid travel no matter where it is.

Does the unit do this, and does it acknowledge this command? If it doesn't and continues to go up. Verify this same procedure but with the door mounted switch.

If you depress the switch and watch the door rise, press the button again and the door should stop no matter where it is in the process.

Please confirm that the unit does this, if it does not you have bigger problems then it not learning . . .