Mighty Mule FM500 blew up green circuit board by reversing battery

Page 1 of 2  

What generally blows up when a Mighty Mule gate opener battery is hooked up in reverse by accident?
I blew up something on the green Mighty Mule FM500 GTO gate opener circuit board. Now I have a constant alarm and the gate won't operate.
I have basic soldering skills. I'm pretty sure the same stuff blows up each time the battery contacts are accidentally reversed.
If you've ever fixed the blown Mighty Mule circuit board, can you tell me which component is the one that fails?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Post a schematic.
There might be a protection diode for wrong polarity. A simple parallel diode protection only protects briefly then the diode blows. A parallel diode with a series thermistor on the power (or fuse) is better, the thermistor acts like a blown fuse when it gets hot, then conducts again when cool. Sometimes a bridge rectifier or series diodes are used. Start testing parts from the battery terminals going deeper. Check any thermistors, fuses or diodes first. Hopefully something in the protection circuit blew and no current got to the functional circuit.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Tue, 5 Jan 2010 07:14:40 -0800 (PST), RickH wrote:

I asked GTO Technical Support but they said they don't have schematics for the green Mighty Mule FM500 circuit board.
Searching the net, I find this great set of GTO circuit board manuals: http://www.centralcoastgates.com/gto%20product_manuals.htm
I was hopeful when I saw what appeared to be the perfect link there: "FM500 Green Board"
However, when I click on that link, unfortunately, I can't read the PDF: http://www.mightymule.com/PDF/Manuals/FM500-Mighty-Mule-g.pdf
Do you have a better PDF to read this Mighty Mule FM500 (green) circuit board schematic?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Joseph Donner wrote:

What? You don't have PDF reader? It's free from Adobe.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I can't read the PDF either. I think it's corrupted or a newer version.
It just comes up blank in my web browser. No error. Just blank.
I'm using the latest Adobe Acrobat Reader.
Maybe the file is corrupt or you need a better reader than Acrobat (foxit perhaps?) to read this PDF wiring diagram?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

I can't read the PDF either. I think it's corrupted or a newer version.
It just comes up blank in my web browser. No error. Just blank.
I'm using the latest Adobe Acrobat Reader.
Maybe the file is corrupt or you need a better reader than Acrobat (foxit perhaps?) to read this PDF wiring diagram?
*** Comes up as 43 blank pages on the latest version of FoxIt as well.
--
Peace,
BobJ



Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Fri, 08 Jan 2010 09:19:23 -0800, Plumber Bob wrote:

I think it's screwed - there seems to be 3 bytes of crap right at the start of the file, which stops it opening in anything.
Getting rid of those lets me pull out version info (PDF 1.4), creation date etc. and it shows up as a 43-page document - but nothing I've thrown it at yet shows anything other than 43 blank pages, so it seems there's some other corruption in there somewhere still (I don't have any PDF fixing tools on the systems here).
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Tony Hwang wrote:

I got curious and tried the link. It looks like one hell of a big file, it was downloading for over a minute when I got scared that it may be a virus and stopped it.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Fri, 08 Jan 2010 12:52:56 -0500, Tony wrote:

I couldn't find a way to read the PDF schematic and nobody knew where there was a schematic for the GTO gate opener (green) was so I had to give up on trying to fix it after I accidentally reversed the 12v battery (you'd think they would have protection circuitry built in for that).
So to give an update to my friends out there ... I just now ordered the Sears Item #00977051000 Mighty Mule FM500 Model R4211 Replacement Control Board (blue) for 322 dollars ($280 + $28 tax + $14 shipping). http://www.sears.com/shc/s/p_10153_12605_00977051000P?vName=Tools&psid=FROOGLE01&sName=Gate+Openers+&cName=GarageDoorOpeners&sid=IDx20070921x00003a
Thanks for your help. I also picked up a few more of the gadgets that go with the gates, so it will be interesting to put it all together when it arrives.
They say to bury the 16 gauge multi-stranded two-wire low voltage wire. I was thinking of putting a PVC conduit in since animals chewing on the wires started this whole mess in the first place.
Do you know what size PVC conduit & how deep to bury low-voltage wires in?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Did you notice the rebate offer on that site?

First, check your local codes.
If your existing wire is type UF intended for direct burial, many jurisdictions do not allow the use of such cable within a conduit. For use within a conduit, type TW (THWN or THHN/THWN) wire is usually required.
The last time I checked, 1/2" PVC conduit can house up to five 12- gauge wires or six 14-gauge wires. Larger conduit makes it easier to pull the wires and add new ones later.
Remember to get a spool of nylon string when you get the conduit.
Good luck.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Sat, 9 Jan 2010 19:36:08 -0800 (PST), RosemontCrest wrote:

Yikes. I will call them back to get the rebate! Thanks.

Interesting. I didn't realize the wire had to be different if it went inside the conduit. Now it makes a bigger difference which way I go, conduit or not.

Is this for pulling the wire through the conduit?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Yes. When you install the conduit, you can either include the string and wires when you glue together the conduit, or you can just include the string. If the latter, when pulling the wires, add another length of string to enable pulling additional wire in the future. Always keep a length of string in the conduit.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Sun, 10 Jan 2010 14:00:42 -0800, Joseph Donner

Leave it in the conduit, when you pull your wires through. Then at some point in the future when you need another wire in there (it always happens) it is easier to pull that new wire in the conduit.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Again, pull a new length of string when adding new wires. Always keep a length of string in the conduit.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Sat, 9 Jan 2010 17:38:12 -0800, Joseph Donner

How many wires? Usually 1/2" PVC works OK. Deep: about 16 inches, if low voltage circuit in conduit. Deeper if possible if no conduit.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

you want to bury pipes and wiring below the frost line in your area. Otherwise ground heave will break them.
--
Jim Yanik
jyanik
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Sun, 10 Jan 2010 13:40:14 -0600, Jim Yanik wrote:

I don't think there is a frost line in San Jose California? Is there a web site I can look this up?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

I've not had that problem here in NH, but if you can, it cannot hurt. Most plastic is flexible enough to withstand the stress of frost.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Sun, 10 Jan 2010 09:49:42 -0500, PeterD wrote:

I will probably put two sets of double-stranded 16AWG wire in the conduit. One set will be for the 18VAC power and the other set for the intercom.
16 inches seems pretty deep. I was thinking more like half that (there is no frost here).
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Sun, 10 Jan 2010 14:02:00 -0800, Joseph Donner

YOu want it below where any landscaping/gardening/maintenance is likely to hit it. That's the 16 inches.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Related Threads

    HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.