Odd Garage Door Opener Problem

[Vikas]

The opener does NOT want to close the door even when it is NOT hooked up. The bottom sensor eye LED is green and if I put my hand to block the beam, the green LED turns off which tells me that sensor is working. And the rejection happens instantly. If I remember correctly the sensor eye reverses the direction of travel when it comes down at least half way. I think something else is wrong. I have already power cycled it. Yes the unit is old, Lift-Master Security+ Model 985. I am NOT inclined to take it apart.

How do I debug this issue? Most of the Google hits do not describe this specific symptom aka "instant rejection while going down".

 

[Vikas]

The emergency way to close the door is I just hold the button until the door goes down completely. That is how I just closed it. Something in the opener electronics is thinking it should NOT close the door but it can be overwritten by keeping the button pressed.

 

[samven]

Normally if it hits something it will reverse direction or if something is in the eye path it will reverse so you could find the 2 wires from the eye and remove them, if that does not work try putting a jumper across those 2 terminals. If it still does not work put the sensor wires back and put a rope through the holes in the bottom rail so you can pull the door down as someone pushes the button. if it works then you need to check your cable or chain tension and pull your emergency release and see that the door moves smoothly up and down. Be careful though because if the springs are not tensioned enough it may be heavy on the way down.

 

[Rand]

try unplugging it for 10min? seems to work for other things.. otherwise.. good luck.

 

[SHOZ]

It's not binding is it and reversing?

 

[tom in boise]

Does it start to go down and then reverse, or just not start down at all? I have had to replace the door control logic boards in my two Liftmaster openers (late '90s production) due to logic card failures. The symptom is the door will close when the hard wired button is pushed, but not with any of the remotes. The remotes work fine to open the doors.

 

[Malo83]

My Genie was acting up this way, found the problem with the sensors, got knocked out of alignment, readjusted the eyes and now works as advertised.

 

[Vikas]

1. The GDO removed power for couple of minutes and tried
2. GDO and the door is disconnected via the hanging rope, so if the door goes down smoothly or off track is immaterial
3. The receiving eye sensor is showing green and if I block it, it green goes away
4. GDO refuses to go down as soon as the button is pressed

 

[Vikas]

Does it start to go down and then reverse, or just not start down at all? I have had to replace the door control logic boards in my two Liftmaster openers (late '90s production) due to logic card failures. The symptom is the door will close when the hard wired button is pushed, but not with any of the remotes. The remotes work fine to open the doors.

Immediately starts blinking the light instead of going down. All buttons, including hardwired wall or the car remote do the same thing. Only way to get it down is to keep the button pushed in until the entire travel is completed.

 

[Vikas]

Here is an interesting thing for somebody who is curious. I think this is how all GDO are operate.

Both safety sensors aka sending and receiving have only two wires coming out *AND* those two wires are connected to the GDO to the same two terminals. Aren't you curious as to how this who shebang works? There is no signal wire coming from the receiving sensor. "All clear" must be riding over the same two power/ground wires. I suspect this was done to avoid somebody bypassing the safety sensor mechanism.

That means even if the sensor shows green light, there is still possibility that GDO does not get that "ALL CLEAR" back because either that part of signal transmitter is broken at sensor (needing new receiving sensor) or the receiving part is broken at GDO (needing new board)

How is that for arm chair diagnosis?

 

[Nukeman7]

Here is an interesting thing for somebody who is curious. I think this is how all GDO are operate.

Both safety sensors aka sending and receiving have only two wires coming out *AND* those two wires are connected to the GDO to the same two terminals. Aren't you curious as to how this who shebang works? There is no signal wire coming from the receiving sensor. "All clear" must be riding over the same two power/ground wires. I suspect this was done to avoid somebody bypassing the safety sensor mechanism.

That means even if the sensor shows green light, there is still possibility that GDO does not get that "ALL CLEAR" back because either that part of signal transmitter is broken at sensor (needing new receiving sensor) or the receiving part is broken at GDO (needing new board)

How is that for arm chair diagnosis?

Vikas, when the sensors are aligned, the receiver puts out a rapid pulsing signal to the GDO circuit board to confirm an unobstructed path at the sensor level. That is why inserting a wire between the terminals to "trick" the circuit board won't work. Last Christmas, the receiving sensor on my 18 y.o. Craftsman (i.e., Chamberlain/LiftMaster) GDO failed and acted similar to what you described; however, the GDO would work normally if the door was disconnected with the emergency release trolley. When the trolley arm is released, the GDO circuit is designed to circumvent the optical safety sensors as there is no longer any risk. I suspect that you have a bad circuit board which is ~$100 online and very easy to replace without dismounting the GDO head unit. If you want to eliminate the possibility of a bad sensor, I guess you could buy the replacement sensors and hook them up directly at the GDO without unbundling the wires so you can return them if it doesn't resolve the problem. I purchased these safety sensors and they worked better than the original sensors:

GDO Safety Sensors

 

[skyactiv]

For the expense of parts and aggravation the opener is causing, a new one can be bought under $200. Door openers aren't made any better or worse today vs 30 years ago.

 

[vwmaniaman]

I was sweeping out our garage and my opener did the same thing. Turns out that I may have bumped the sender with my broom. I also had green leds on both boxes. I replaced a 1 mfd and a 100mfd in the receiver box which I also replaced 10 years ago. Helped but was intermittent. I re-positioned the sender and all is good. In case you did not know a cell phone with a camera can see the infra red beam. Use your phone to verify the beam position. This also works to verify TV remotes are working

 

[Vikas]

My GDO is pretty dumb and does not have any idea if the trolley is connected or disconnected. If it were smart enough, it would know based upon the motor current but it does not. I will be debugging it with the trolley disconnected to avoid the door itself moving. Plan of action is to go after the sensor first and even try new ones as long as I can find the one which looks similar to existing ones and test them out right next to the opener. I presume I won't even have to remove the existing sensor because these two could just run in parallel to them and if the sensors provide the pulsing and get the opener closing then I can swap the sensors. If that does not work, then have to get the new board. That would mean resetting all the remotes which is the part I hate the most! Any chance that remote control board is different than the motor control board?

 

[dishdude]

The sensors are universal, you can buy a set for around $20 at Home Depot. I'd hook them up at the opener and set them up on top of your step ladder just to test.

You might want to consider replacement, mine died last year and all the new Chamberlain/Lift Masters have Wi-Fi. It's nice opening and closing the door from your phone and Amazon can place deliveries in your garage. After I got the new one in, I was actually happy the old one had died since it was a nice upgrade.

 

[Vikas]

What kind of voltage (AC or DC and what how much) is supplied to the sensors? My DMM has frequency measurement. If the GDO does not receive pulses, then it would be easy to indict the sensors without disconnecting anything.

 

[Vikas]

GREAT NEWS! Just little bit of tweaking the receiver sensor and now the door came down fine. I am NOT touching anything until the problem repeats. The presence of green light had me fooled. I moved it little bit and the LED could have become brighter but I am not sure.

Thank you all for helping me out here.

 

[Vikas]

The sensors are universal, you can buy a set for around $20 at Home Depot. I'd hook them up at the opener and set them up on top of your step ladder just to test.

You might want to consider replacement, mine died last year and all the new Chamberlain/Lift Masters have Wi-Fi. It's nice opening and closing the door from your phone and Amazon can place deliveries in your garage. After I got the new one in, I was actually happy the old one had died since it was a nice upgrade.

I have installed MyQ add-on which has been working fine. That was very cheap and gave me the WiFi and the phone control and monitoring of the garage doors. It also supports Amazon Key but I do not use it.

 

[Nukeman7]

Excellent outcome, Vikas. Now go enjoy the outdoors before the next cold front hits!

 

[mk378]

Check that the sensor lenses are clean. Move a sensor each way (up and down and side to side) until the light goes out. Then set it back to the center of the area where the light stays on. Do this first with the transmitter then with the receiver.