Mighty Mule 502 repair

[cappyD]

Thanks to this site I've learned more about my gate opener in the past 30 minutes than I have in the past 2 days blindly searching the internet.
My MM502 was bought by the previous homeowner so I have no idea where or when it was bought. The wiring was already installed as well as all the mounting brackets but the arms were never installed. I dove into this project without knowing the first thing about gate opener. I put both arms on the brackets and double checked all the electrical connections and to my surprise it worked. Both gates opened and closed but there were just a few tweaks to be done. I adjusted the brackets mounted on the posts and gates so everything was perfectly level. After my adjustments I had a hard time putting the arms back on. I managed to get the master arm adjusted perfectly. The slave was a little more difficult because the post wasn't exactly installed like the master. It was a little lower and turned in a bit. Once I got everything as level as possible I tried to install the arm but the holes didn't match up. I (not thinking) pulled on the gate pretty hard to install the arm. I also screwed the arm in possibly too far in order to line up the holes and mount the arm.
Now when I activate the remote the master side works perfectly but the slave side only closes the gate about 1/2 an inch and stops. When the slave stops an alarm sounds. It is 1 beep per second and it doesn't quit unless I turn the board off.
I swapped the wiring on the board master/slave, slave/master. Same problem.
I think I damaged something inside the arm. I want to take the arm apart and replace whatever I need to but the casing seems stuck. I removed the screws thinking the arm would come apart but it seems stuck. I don't want to force it apart and break something else. I have learned that replacement parts are expensive.
Actually I have learned a lot since I broke the daggum thing.
This is the only website I have found discussions in detail about replacing parts. I hope I gave enough details to help someone help me. I will provide any other information needed such as measurements or pictures if anyone needs them.
Thank you in advance to anyone that has advice or even just points me in the right direction.

 

[BeezFun]

Here's the manual. I had one of these many years ago, spent more time fixing it than it was worth. Had problems with control board failing, replaced several times. Had problems with differential contraction of bushings in gate arms when it got real cold, replaced those. Only good thing I can say was the company was very helpful and kept sending me stuff for free because it was relatively new.

 

[cappyD]

I took the arm apart and located the limit switch.
When the arm is completely retracted and I push the remote everything starts okay. When it moves about an inch the limit switch releases. That is when the arm stops. It will not move again until I manually screw it back in and it touches the limit switch. Does that mean the limit switch is bad or does it mean something else?
Any help at all is appreciated.

 

[flyerdan]

When I worked for a fence company I was constantly pulling openers out of the trash and taking them home for parts. Mostly the cheapies with the rectangular sleeve, but I do have a 502 in the pile, I'll take a look at it and see what I can find out.

 

[cappyD]

Thank you for your time. I just wanted to add that it is my slave arm that is not working correctly but when I connect the master arm to the slave connections (on the board) the master arm works perfectly.

 

[cappyD]

I can absolutely verify that it is the limit switch I have to replace. I took it off and took the limit switch apart and found the tiny spring inside was a little corroded or rusted. I wasn't getting any spring action that would allow the arm to get power in it's normally open position.

 

[caricia78]

my master arm randomly started to over retract and get stuck every time it opens and sound the alarm. any way to fix this?

 

[weldingisfun]

my master arm randomly started to over retract and get stuck every time it opens and sound the alarm. any way to fix this?

Have you tried calling the GTO Service Department, 800 543-1236? The number is in the manual Beezfun attached to his #2 post. They are very helpful and have helped me out several times over the years.

 

[Soundguy]

check the stop sensors in the arm if it is out of warranty.

 

[caricia78]

I think you are right about the stop sensors..its still in warranty but problem is this is the arm that is farthest fromt he box and I have the wiring going under my driveway in a conduit..would be a big pain to remove
And I think the customer service department just reads through the same online help handouts and then if they cant solve it tell you to send it in.
so I ended up fooling around with it and turning the extension arm a little in and a little out, with the system ON, until I heard the box beep, which I assumed was its way of telling me that this was the point it triggers the open limit..so I made sure that in the fully open position the arm was retracted to just past that beep and not a millimeter more, and that seemed to work and now it opens without jamming itself, but that arms still retracts a lot more than the other arm (its a dual gate opener)..must be something with the stop sensor or limit switch (is that the same thing?) inside thats off..as you said. hopefully it works now but this did happen also while I was installing it and then it stopped, so if it happens again under warranty ( I still have 13 months) I guess Ill send it in unless anybody can tell me how to open it up and check the stop sensor???
thanks!

 

[Soundguy]

i would not open it up if under warranty....

 

[caricia78]

Ok so it worked about ten times and then today jammed up again when I opened it. If anyone can tell me.how to fix this is appreciate it because I really don't want to have to send this thing back in after I fished the wire 20 feer under my driveway and spliced it because the cord wasnt long enough to reach the board. Better yet I will pay wholesome to come fix this if they can come to San Diego.
Thanks, Rebecca

 

[Soundguy]

do your wires not disconnect at the arm from the board with lil quick terminals?

 

[caricia78]

do your wires not disconnect at the arm from the board with lil quick terminals?

yes they do... but the conduit runs under my driveway and is about 5 feet deep on each side...so Id have to dig out each side, pull the wire through..but the more difficult part would be installing the new one with having to hire an electrician to splice the wire again because the cord attached to the arm wasnt long enough to reach the board, and then fishing it through the conduit under the driveway again
got it working one more time with resetting the limits..but not sure how long it will last

 

[TractorGuy]

yes they do... but the conduit runs under my driveway and is about 5 feet deep on each side...so Id have to dig out each side, pull the wire through..but the more difficult part would be installing the new one with having to hire an electrician to splice the wire again because the cord attached to the arm wasnt long enough to reach the board, and then fishing it through the conduit under the driveway again
got it working one more time with resetting the limits..but not sure how long it will last

When you pull the wire out just tie a string on it to pull the new wire back through with.

 

[caricia78]

When you pull the wire out just tie a string on it to pull the new wire back through with.

good idea, thanks
big question is...does anyone know if its NOT okay to splice the cable from the arm to get it to reach to the control board? because the manual says you should never splice the wire, but in order to cross my 2 -10 foot gates that have an additional 3 feet of fencing on each side, and go down into the ground 4-5 feet on each side, I needed more wire than the 36 feet provided on the slave arm? its been working ok for 4 months, and now just started giving me trouble so doubt it is the splice...but I have no alternative to splicing anyways..
any thoughts?

 

[JimRB]

I would bet the manufacturer has seen lots of poorly done splices that corrode and cause gate malfunction or control board issues. A solution is to use waterproof splices that are packed with a silicone sealant or buy a longer and larger gauge 50' wire to connect to circuit board. 3M Products 3M63-NBM-A-25 Butt connector, Vinyl, 12-10 gauge/25 pack | TESSCO

 

[Soundguy]

electron flow is electron flw. a good splice can be done better than the connection that a plug makes.

I still don't see the problem with de-wireing the board.. no pulling involved..e tc.

 

[caricia78]

electron flow is electron flw. a good splice can be done better than the connection that a plug makes.

I still don't see the problem with de-wireing the board.. no pulling involved..e tc.

what do you mean by de-wireing the board?
well I called today and GTO customer service troubleshooted with me about 15 minutes then just told me to send in the slave arm and the control board to try to diagnose and fix it. they had me manually turn the arm so that it was screwed all teh way in, then turn it on and set the limit from that point, which didnt work.
the interesting thing is that every time I reset the limits, the gate works for 5-10 cycles repeated one after another right after I fix it. Then, it seems if I leave it alone for a while and then go back to actually use it for a purpose and get my car out of the driveway, the slave arm opens too far and jams up again. I have spent probably several hours now trying to figure it out.. and when I disconnect that arm from the gate, interestingly, I cant reproduce the problem. But when its connected, low and behold- it jams.
I was thinking of trying to just send them the control board first to avoid the hassle of removing all of my threaded cable and see if the control board is the issue.
but regarding the splicing, I clarified with them today and the cables are 6 foot and 32 foot on the arms, so I actually had to splice and extend the wiring on BOTH sides when I installed it...

 

[Soundguy]

i believe the splices will be a NON issue if done correctly, and kept dry and corrosion free. PS.. i'd reccomend soldering, shrink tubing and sealer.

I would suspect the problem is inthe actual limit sensors int he arm.. not the board.