Liftmaster gate operator stops opening at night


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Old 02-12-22, 05:52 AM
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Liftmaster gate operator stops opening at night

I have a pretty new Liftmaster SL585 that seems to work perfectly during the day but stops opening every night and is driving me nuts. The gate will open and the reverse as though it is hitting an obstruction but there is nothing there. On the open there is one Liftmaster LMRRUL.

I have had a technician out multiple times but they seem clueless. My latest thoughs are maybe the cold weather at night is impacting the operation. The system has two photoelectric eyes and the green and white wires for both (heat?) are wired to the same terminals on the board.

If anyone has experience with these and would help me troubleshoot I would be very grateful. Thanks!
 
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Old 02-12-22, 06:27 AM
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Check the inside of the photobeam units for condensation. If you are having significant temperature swings from day to night, moisture _could_ be affecting it. Not knowing if you have actual loop detectors, that's what normally handles the obstruction detection.

If you don't have the installation manual with the troubleshooting guide, I recommend getting one while you can, because gate operator manufacturers routinely delete manuals for discontinued models.
https://d1j8pv6a7q833y.cloudfront.ne...20200203212758
 
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Old 02-12-22, 07:58 AM
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Check the inside of the photobeam units for condensation. If you are having significant temperature swings from day to night, moisture _could_ be affecting it. Not knowing if you have actual loop detectors, that's what normally handles the obstruction detection.
We are in the Northeast so the high/low temperature swings could be 20 degrees Fahrenheit or so. It is quite frustrating, I can be there all day and open and close the gate 50 times to test it out with not a single error but once it gets dark the gate starts failing - always on the open. I am never there once this starts happening but I will try and be there this week.

Our safety devices setup: LMRRUL and wireless edge on the close; LMRRUL on the open. We also have one loop detectors but I do not think that is the issue. The diagnostic code is 75.

The LMRRUL has a built in heater and it is powered from the accessory port on the main board, can the accessory port power both LMRRUL devices or could that be the issue? Could I need to use an external power supply?

I am really at wits end because I cannot duplicate the issue when the technician is there (during the day) and he goes through the tests and everything works fine. Without fail though the gate stops working at night and I have the videos that demonstrate that.

If there is anyone that has Liftmaster experience and can provide guidance I would be most appreciative.
 

Last edited by ac1987; 02-12-22 at 08:20 AM.
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Old 02-12-22, 10:06 AM
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It's been years since I worked on a lot of these, and every gate install is essentially a customized setup. However, these sensors are pretty similar to the fire beam devices I work with, regularly. My gut instinct is that there is _something_ in the night time lighting conditions around this photo beam unit that is making the reflected beam act as if there is an obstruction. It could be a shadow, another light source, some reflection, or even a vibration affecting the beam unit, or the reflector.

I strongly doubt that the aux power output is an issue.
https://entryandexit.com/manuals/lif...duct_guide.pdf
 
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Old 02-12-22, 07:52 PM
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Only the LMRRUL would protect on opening as the gate is sliding away from the driveway.
Could I need to use an external power supply?
Very possibly.

The control board can handle 500ma ext load max.
Each LMRRUL needs 190ma with the unit and heater combined. That's 380ma.
Plus the edge detector and maybe the loop detector.

 
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Old 02-14-22, 10:56 AM
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Only the LMRRUL would protect on opening as the gate is sliding away from the driveway.
Can you explain what you mean? We have two LMRRUL devices, one on the driveway and one for the entrapment zone in the rear of the gate where it slides open.

​​​​​​​The control board can handle 500ma ext load max.
Each LMRRUL needs 190ma with the unit and heater combined. That's 380ma.
Plus the edge detector and maybe the loop detector.
How difficult is adding a plug transformer? Is it something I can do or best to have an electrician or gate tech? It looks like I would just take the green and white wire to the terminals on the transformer, is that correct?

​​​​​​​Thanks
 
 

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