Mighty Mule 502 Solved (maybe)

[cappyD]

This is what I've been working on for the past month or so. If you have ever searched for help with your Mighty Mule you probably know it's useless. There are some good troubleshooting guides out there but if your problem doesn't fit exactly in to a certain category then you are out of luck. I would get so close to a diagnosis using a guide but right at the end everything would fall apart. Usually my readings would be correct but the troubleshooting guide didn't elaborate about what to do in that case. Or it would say something like "If the voltage is between 12.5 and 14.5 the arm is good. Replace the board". I was usually left wondering why not fix the board? Or atleast give me one (or a few) things to test on the board. A new board costs over $230.00 so I'd like to be 100% sure there isn't a bad relay or something else I could fix or someone else fix. Anyway, here's my experience with the gate opener. Maybe some other person will gain something from it. Even if they learn what NOT to do.

After only a few months of having a great worry-free gate opener it bit the dust here recently. My first little issue was about 6 months ago with the slave arm limit switch. Not a big deal to remove it, clean and adjust the little spring inside of the switch.
During that time of researching gate openers I seen where a lot of people had problems with the control board. I was always careful when I had to work directly with the control board. I added a few accessories and everything was fine for about 6 months.
A month or so ago the slave arm started stopping mid-cycle for what seemed to be no reason. Soon after it started that issue it completely stopped working. Since I already had to work on the limit switch I was very familiar with the wiring for the operator arms. I did the usual troubleshooting. I swapped master with slave terminals, swapped rev counter boards, I even connected the slave motor directly to the battery. Everything checked out good. I could not find anything wrong with connections, voltage, rev counter boards, or stall force.
The only reasonable conclusion I had was something in the control board was bad.
Most normal people would just replace the control board and bypass the hours (days) of poking around with a multimeter without knowing anything about control boards. It was impossible to find schematics for the R4211 blue board anywhere on the internet. I was able to find the schematics for an older type Mighty Mule which did help me a lot.
Since I knew exactly nothing about diodes, capacitors, or resistors I couldn't definetively point to the cause of my problems. I was basically confirming voltage was present at different points. When I did think I found a problem I had no way of knowing what the correct reading should be. So I was unable to confirm any component was bad. I gave up on that after a while. That's when I came up with an idea that I never did see on the internet or anywhere else. Here goes...

So here are my symptoms and here is what I did to "fix" it.
With both arms connected in their proper terminals I push the remote and nothing moves. I can hear a click sound (relay?) and the yellow status light flashes 5 times + 1 second pause, then flashes 5 times + 1 second pause. It will continue to flash until I turn the control board off and back on.


******** It may also be giving an audible alarm of 5 beeps as well. I don't know for sure because I removed the speaker. It was very loud and CONSTANT at times.********


If I leave everything connected nothing moves. Doesn't even try. But if I remove the slave arm orange wire or green wire from the control board the master arm works fine. When I swapped master/slave terminals the exact same thing happens. So I know for sure 100% that the issue is in the control board (right??).
After probing and testing and giving up I finally tried this.
I disconnected all of the slave wires from the control board. I twisted the red and black motor wires from the slave arm to the master arm red and black wires. (Red to red and black to black)
After twisting them very tightly and carefully attatching them to the master terminals on the control board everything is back running great. I only had to adjust the slave arm closing distance manually by screwing the tube a little. Both arms open at the same exact time and stop at the exact same time.
As far as I know it seems to be safe to do this. Nothing seemed strained or weak and it sounds normal too.
There are a lot more details to this.
I've learned quite a bit about my gate opener over the past month so if I can help anyone just ask. I'm still not an electronics expert but if I can help just let me know.

********* If you know I am damaging something or if it's not a good idea to connect the slave motor wires to the master motor wires please let me know********

 

[renest]

Thank you for your post, I have been having problems with Mighty Mule, I have been able to repair several problems with these boards, but my main problem is that I cannot get schematics for them. I have an extensive electronics training and background, but without a schematic it is like going to a strange state or country without a map, you know that there are roads that go between cities, and connect with other roads, but which leads to what city, and what road connects to what road. This leads to a lot of educated/experienced guessing. In your post, you stated that you managed to locate a schematic for an older board, can you direct me to your source for it? Anything would be helpful, and I will be glad to help you if I can. As far as paralleling your actuators, you are drawing more current through the relay contacts, I don't know if the relay contacts will continue to support twice as much current or not. Any help on the schematics will be appreciated.

This is what I've been working on for the past month or so. If you have ever searched for help with your Mighty Mule you probably know it's useless. There are some good troubleshooting guides out there but if your problem doesn't fit exactly in to a certain category then you are out of luck. I would get so close to a diagnosis using a guide but right at the end everything would fall apart. Usually my readings would be correct but the troubleshooting guide didn't elaborate about what to do in that case. Or it would say something like "If the voltage is between 12.5 and 14.5 the arm is good. Replace the board". I was usually left wondering why not fix the board? Or atleast give me one (or a few) things to test on the board. A new board costs over $230.00 so I'd like to be 100% sure there isn't a bad relay or something else I could fix or someone else fix. Anyway, here's my experience with the gate opener. Maybe some other person will gain something from it. Even if they learn what NOT to do.

After only a few months of having a great worry-free gate opener it bit the dust here recently. My first little issue was about 6 months ago with the slave arm limit switch. Not a big deal to remove it, clean and adjust the little spring inside of the switch.
During that time of researching gate openers I seen where a lot of people had problems with the control board. I was always careful when I had to work directly with the control board. I added a few accessories and everything was fine for about 6 months.
A month or so ago the slave arm started stopping mid-cycle for what seemed to be no reason. Soon after it started that issue it completely stopped working. Since I already had to work on the limit switch I was very familiar with the wiring for the operator arms. I did the usual troubleshooting. I swapped master with slave terminals, swapped rev counter boards, I even connected the slave motor directly to the battery. Everything checked out good. I could not find anything wrong with connections, voltage, rev counter boards, or stall force.
The only reasonable conclusion I had was something in the control board was bad.
Most normal people would just replace the control board and bypass the hours (days) of poking around with a multimeter without knowing anything about control boards. It was impossible to find schematics for the R4211 blue board anywhere on the internet. I was able to find the schematics for an older type Mighty Mule which did help me a lot.
Since I knew exactly nothing about diodes, capacitors, or resistors I couldn't definetively point to the cause of my problems. I was basically confirming voltage was present at different points. When I did think I found a problem I had no way of knowing what the correct reading should be. So I was unable to confirm any component was bad. I gave up on that after a while. That's when I came up with an idea that I never did see on the internet or anywhere else. Here goes...

So here are my symptoms and here is what I did to "fix" it.
With both arms connected in their proper terminals I push the remote and nothing moves. I can hear a click sound (relay?) and the yellow status light flashes 5 times + 1 second pause, then flashes 5 times + 1 second pause. It will continue to flash until I turn the control board off and back on.


******** It may also be giving an audible alarm of 5 beeps as well. I don't know for sure because I removed the speaker. It was very loud and CONSTANT at times.********


If I leave everything connected nothing moves. Doesn't even try. But if I remove the slave arm orange wire or green wire from the control board the master arm works fine. When I swapped master/slave terminals the exact same thing happens. So I know for sure 100% that the issue is in the control board (right??).
After probing and testing and giving up I finally tried this.
I disconnected all of the slave wires from the control board. I twisted the red and black motor wires from the slave arm to the master arm red and black wires. (Red to red and black to black)
After twisting them very tightly and carefully attatching them to the master terminals on the control board everything is back running great. I only had to adjust the slave arm closing distance manually by screwing the tube a little. Both arms open at the same exact time and stop at the exact same time.
As far as I know it seems to be safe to do this. Nothing seemed strained or weak and it sounds normal too.
There are a lot more details to this.
I've learned quite a bit about my gate opener over the past month so if I can help anyone just ask. I'm still not an electronics expert but if I can help just let me know.

********* If you know I am damaging something or if it's not a good idea to connect the slave motor wires to the master motor wires please let me know********

 

[cappyD]

Renest
I apologize for the slow response. So far since I read your post I have been only to find the schematics for a Mighty Mule 202. It is an older board that has different options than the MM502 but maybe you can make more sense of it than me. The link I am posting has pictures of the board and lots of technical information about the MM202. I'm not sure which model Mighty Mule you have.
My gate has been working great for a few months now but I went through the same ordeal as you and others trying to find any wiring diagrams and technical information on these boards. I will continue to look for more schematics that I have collected and will post them as I find them. I have tons of information on these arms and boards so please don't hesitate to ask when you start troubleshooting.
https://drive.google.com/folderview?id=0BzMQIArA32bWSS1JSERFMGlTY0U&usp=sharing

 

[raysmoot]

cappyD
I have read your post. I like you thought process. I have the old board that has also quit working. Could i get a copy of the schematic you mentioned?
from you post:

"I was able to find the schematics for an older type Mighty Mule which did help me a lot."
thanks,
ray.

 

[Cartman]

I recently had the EXACT same problem as the original poster. The board appeared to be in good shape. No corrosion or burn marks. I did some poking around and finally came to the conclusion that it HAD to be the relays. I didn't have any schematics to help me prove it... but I felt it was worth the "risk" of killing the board - because if that didn't fix it, I would need a new one anyway.

I decided to attempt to swap out the relays on the SLAVE side of the circuit board. After looking at the relays on the board - I saw the markings"RWH-SH-112D". I found the spec page here: http://www.goodsky.com.tw/files/New Datasheet/RW-RWH_relay.pdf

I could not find those relays at local parts stores, so I went searching online. I could not find exact replacements, so I had to settle for something close. I ultimately found the parts I used at www.DigiKey.com: 1461069-5 TE Connectivity Potter & Brumfield Relays | PB1321-ND | DigiKey

The current rating was a little lower that the originals - but I was OK with that. Worse that happens in the relays die (again). I decided to order 10, just in case I needed to replace all of the relays (there are 5 on the board), or if I managed to break some somehow. Plus, I would have replacements on hand just in case this ever happened again.

So I bought a $3 soldering iron from Harbor Freight and got solder, flux and solder wick from a local electronic hobby shop (you can get online too if you really want/need to). I used the solder wick to get the solder out of the holes for the problematic relays. One of the relays popped right out, but the other one was a little harder. I had to keep moving around to each leg of the relay with the iron and push a little on each one until the whole thing worked its way out. Just be careful not to dump too much heat for too long into the board... or you could cause problems.

Once the relays are out, you can use the solder wick to clean up any excess solder in the hole so the new parts go in easy... then solder the new parts in. Put the board back in the control box, wired everything back up, and it worked!!!

Overall... it took less than an hour to disconnect the board, remove the the SLAVE relays, put new ones in, and put it all back together. The final cost to fix this was under $15 for parts and supplies. I think that is better than $230 for a whole new board.

So - if anyone else ever encounters this problem... hopefully this trick works for you too.

I wasn't a member of this forum - but was one of the places I found when searching for my gate opener problem, so I wanted to share the love and let you know what I did to fix it.

Anyway - sorry to bring up an old thread. Just thought it would be helpful for anyone else experiencing the same or very similar problems.

 

[dennisoates]

Hello Cappy, thanks for all the good info.
I have dual gate mighty mule openers i bought used. i hoooked them up and they both move 2 inches and stop, when i hit the remote they move back 2 inches, beeps 4 times. I wire them direct to the battery and they both rapidly extentend, and retract. i have hooked them up without the slave, and they still only move 2 inches and stop. I have a 3rd am and hook it up and it moves 2 inches and stops. there are binding or obstructions in the gate as i even tried running them unhooked from the gate. the batteries test good at 13.50. I have tried called the company, but can never get thru, hope you have some good advise for me. thanks. I am not sure how to test the circuit board with the meter.

 

[dennisoates]

mine is a MM 2500

 

[Cartman]

Not sure if you have stumbled across this site or not, but it has some useful info: Gates That Open (GTO) Support Center - Trouble Shooter Wizard

I remembered looking through most of these documents when I was looking at the gate I repaired the other day. Check out these:

See bottom of page 6: http://support.gtoinc.com/Uploads/Documents/0500 Audible Alarms.pdf
Here is how to test: http://support.gtoinc.com/Uploads/Documents/0500 Rev Counter Test.pdf

They have some picture that show you the connections for testing with a meter.

You have 3 different arms acting the same way on the master channel of the board. Plus you mentioned that they extend/retract with direct power, so I am pretty confident that the problem lies somewhere on the control board (probably intermittent relays). I never got schematics of my exact system to confirm it, but I suspect the blue/white wires go to the rev counter board in the arm, and the orange/brown connect to the limit switch in the arm. The green wire is probably "ground" for the control systems in the arm. All that to say - those are the signals that are controlling the relays. The odds of 3 arms being bad in the exact same way is unlikely. If I was going to try and fix this before replacing the board, I would try swapping the relays. Even if you think you hear them clicking - it doesn't mean they are working properly. I learned that the hard way.

Good luck!

 

[dennisoates]

that sounds like its worth a try. do you think its worth asking them at mighty mule, or will they just want me to buy a new board?

do i need to replace both relays? is one for the slave? could they both be bad, or do they both work together for both arms?

 

[Del Dad]

that sounds like its worth a try. do you think its worth asking them at mighty mule, or will they just want me to buy a new board?

do i need to replace both relays? is one for the slave? could they both be bad, or do they both work together for both arms?

It turns out that with the GTO FM500 series the 5 beep alarm indicates a problem detecting the charging circuit (even if there is no problem with the charging circuit). Despite the alarm my batteries are charging just fine. GTO acknowledges this. Turning off the power switch resets the board and it will work fine one-time. Then the beeping starts again the next time you try to use it. If I disconnect the incoming power feed the unit runs perfectly off of the batteries. Clearly there is a defect on the board that should be recalled rather than forcing owners to spend an obscene $300 on a replacement circuit board that is practically OK.

I am purchasing an $8 12V charge controller. I will then disconnect the power feed and attach it to the controller. The 12V output from the controller will splice into the battery wires, effectively charging the batteries and bypassing the charge sensor. Here is a link to the controller I bought.

6-6v lead-acid Battery Charging Controller Protection Board switch 12v 24v 48v | eBay

Worth a try prior to buying a new circuit board. Hopefully this will prevent GTO from continuing to take advantage of their customers.