LiftMaster Door Operator

[caribconsult]

Thanks to everyone who replied recently and you all make a somewhat similar point. This unit is apparently a very old design, it is put out on a limited basis, possibly re-manufactured (not that that's an issue) and perhaps available only in certain markets. Lots of you inquired about the PC board part, which plainly doesn't exist in this model. So it's quite possible that very few have had experience with this particular model. This is Puerto Rican engineering at it's finest, as I said before. I started coming here back in '72 and I saw some amazing 'engineering' workarounds back then and this philosophy continues. There's also the factor that this unit is about half the price of a legit LM gate opener. That's a big factor here in our economy. So it is what it is. I hope the technician they send knows what they are doing and has some test gear to measure things if it screws up. If not, I'll probably just send him home. I don't yet another observer telling me it doesn't work right. I know that. I want some answers. Wish me luck!

 

[caribconsult]

UPDATE: We had a genuine LiftMaster technician here last week and although we could not get the unit to 'screw up' as described previously (it is was intermittent, as stated), he studied the operation carefully and his take was that the large 2 ohm ceramic resistor was intermittent, possibly due to the heat generated, and that would definitely cause a power outage during operation. He told me he had seen that problem previously and the resistor was the issue. So he replaced it, and the gate has been operating without a problem for almost a week now. We have our fingers crossed.

I want to express my undying thanks to all the nice folks who contributed their wisdom in this thread, particularly those who explained the function of the RC circuit and how it produces the two different rotations of the motor. And also, that the motor was indeed a brushless design, which eliminated several possible sources of the problem. I had never heard of a split capacitor motor before. Un montón de gracias, as they'd say here - thanks to all of you and pray for us, please!!

 

[caribconsult]

Ahh, the perils of speaking too soon. The gate screwed up again, today, several times. I spent almost two hours on the phone with a pretty knowledgeable tech from Liftmaster's support at Chamberlain and we tried everything, from bypassing the RC circuit, changing the cap, sending line voltage directly to the motor, measuring voltages at different points and absolutely no success. It's not the RC circuit, not the relays, not the little transformer, so what's left but the motor? Likely a broken or disconnected winding, since it doesn't have that unique smell from burning out. What I learned from LM is that this unit is NOT intended for rolling gates, nor outdoor use and as such, Liftmaster will not honor any warranty on this. So we've been caught in the trap of local engineering, sort of an oxymoron. We've spoken the seller of this unit, indicated to him that we now know he never should have sold us this, and we want to know what he intends to do about it. Wish us luck. And thanks again to the many contributors who tried to help me with this. "Les agradezco mucho", as we say here...I appreciate you all a lot.

 

[McLintock]

This is what was hard while I was in the garage door business. Was it cheaper to trouble shoot or replace? 9 times out of ten was cheaper to replace.


“ shoot low boys their riding shetland ponies”

 

[caribconsult]

This is what was hard while I was in the garage door business. Was it cheaper to trouble shoot or replace? 9 times out of ten was cheaper to replace.


“ shoot low boys their riding shetland ponies”

That's our plan. We've had two failed units of this type, the MJ5011 non-logic board model, and we're not going to accept another. We've sent out messages to the guy who sold us this that we don't want it repaired or replaced with another. We want something designed for rolling gates and we're willing to pay the difference, or he can wind up seeing his name in print and it won't be nice. I have a hard time accepting that this unit is so commonly used here for rolling gates when Liftmaster says specifically it is not for this type of use, nor for outdoor use. As I said, local engineering.

 

[kwired]

That's our plan. We've had two failed units of this type, the MJ5011 non-logic board model, and we're not going to accept another. We've sent out messages to the guy who sold us this that we don't want it repaired or replaced with another. We want something designed for rolling gates and we're willing to pay the difference, or he can wind up seeing his name in print and it won't be nice. I have a hard time accepting that this unit is so commonly used here for rolling gates when Liftmaster says specifically it is not for this type of use, nor for outdoor use. As I said, local engineering.

I was thinking all along you were using it for something it wasn't designed for, did not focus on what may have been done to weatherproof the main drive unit, did try to tell you how it works so you can hopefully figure out what was not working. Don't know if whatever failed is because of non intended use or not, but can understand manufacturer not wanting to stand behind something not used as intended. Whoever modified it is who possibly should stand behind it.

This possibly is significantly less expensive than something that is designed and listed to do the task, and probably the reason there are so many where you are.

 

[caribconsult]

KWIRED, I think you hit the nail on the head. According to Liftmaster, this non-logic board design dates back to the early 2000's, and has not been made since then, so the fact that ours has a label showing date of mfg of Feb, 2019 likely means it was an old non-functioning unit that was refurbished on that date, but still an old design, and LIftmaster was quite emphatic about the non-authorized use of this outdoors and for rolling gates, which voided any warranty coverage we might have had. It's not hermetically sealed, just has a steel case cover over it, but that does nothing to protect if from the highly corrosive humidity and heat we have that has destroyed much electrical equipment over the almost 18 years we live here.

As I said in my most recent post, I, along with a knowledgeable tech (who at first couldn't believe we actually had this model...I had to send him a photo!), we spent two hours troubleshooting it and it appears the motor is dead...not burned from overload...it doesn't have that unique smell of burnt electrical equipment, so more likely a winding failed or some other part failed and not from overload. I have a fairly deep knowledge of electronics and electrical equipment...I can use an oscilloscope, signal generator, and various meters since I'm a kid and I understand exactly what tests we did, and even when we ran the line voltage directly into the motor there was no response. If that doesn't prove dead motor than I don't know what would. I also have a pretty deep understanding of our existing Tesla system, so electrical systems are not a mystery to me.

And your last sentence about the lower cost factor explains a lot....here in PR, many contractors will generally try to give you the cheapest solution, even if you ask for a good one. That's exactly what I meant by 'local engineering.' We intend to hold the seller's feet to the fire over this, and offer him the opportunity to either replace it with a proper unit, for which we will pay the difference, or just take it back and refund our money, or there will be more onerous consequences. We definitely do not want it repaired. We want it gone.

It appears NONE of the Liftmaster dealers here are aware of the use restrictions and non-warranty policy of Liftmaster regarding this usage. I've spoke to two different ones and neither mentioned this issue at any point...their response was 'we use this unit all the time,' which fits your analysis perfectly. That's their problem, not mine. Thanks for your input and I will post any solutions that surface.