Wiring for Mag and Points

This AC WD (1950) is new to me and has not run in six years. I am getting ready to try to start it, but believe the wiring as I found it was incorrect. The wiring photo shows that a black wire with a red lead coming from the coil is incorrectly attached behind the condenser. I believe it should go to bottom of the points (RED XXX). Condenser should also go to RED XXX, as should the black wire coming from BEHIND the coil (I'm not sure where it is coming from, but I suspect it's a cut-off switch, as the tractor does have an "On/Off" switch.

Can anybody tell me what the correct way to wire the ignition is????

It is a fairbanks morse mag.

I should add that this is a 12 volt system and it is a positive ground system. At least that's the way I found the tractor....

Thank you,
Billy
AC%2520points.jpg


AC%2520mag.jpg
 
This AC WD (1950) is new to me and has not run in six years. I am getting ready to try to start it, but believe the wiring as I found it was incorrect. The wiring photo shows that a black wire with a red lead coming from the coil is incorrectly attached behind the condenser. I believe it should go to bottom of the points (RED XXX). Condenser should also go to RED XXX, as should the black wire coming from BEHIND the coil (I'm not sure where it is coming from, but I suspect it's a cut-off switch, as the tractor does have an "On/Off" switch.

Can anybody tell me what the correct way to wire the ignition is????

It is a fairbanks morse mag.

I should add that this is a 12 volt system and it is a positive ground system. At least that's the way I found the tractor....

Thank you,
Billy
 
Can anyone tell me how to display images using the "Classic View?" Also, I have no trouble editing a post in the "modern view" but cannot see a way to edit in the classic view. Any suggestions?
 
I am not familiar with that Magneto nor do I have a wiring diagram so I can ONLY offer some technical guidance which may or may not help. If you understand how things work you can figure out how to wire or troubleshoot it without a diagram in my opinion.

If its truly a MAGNETO equipped with a grounding kill switch circuit???? instead of a battery powered coil ignition system:

The UN grounded (except when points are closed) points wiring terminal could have 3 wires;

One is small LV Primary wire out of coil
One is the Condensor
One is kill switch wire which may lead to a pass
through insulated stud/terminal where a wire is
attached outside up to a dash mounted kill
switch that, when grounded, kills the spark.


That make any sense or help you wire it??

DISCLAIMER: This may be right or it may be wrong, its worth what you paid NOTHING, so take or leave it at your own peril.

John T
 
Hi John,

Thank you for the response. I'm leaning toward what you said. There is an on/off toggle switch on the dash, that I believe is the kill switch. But just as you said, I'm not certain.

Hoping an expert will weigh in.... I'm new to ignitions and will eventually figure it out.
 
"There is an on/off toggle switch on the dash, that I believe is the kill switch. But just as you said, I'm not certain."

I can tell you how to be certain:

If its really a Kill Switch designed to kill a Magneto Spark and its basically an On/Off or Stop/Run type of switch;

One wire goes down to that KILL terminal/stud on the Mag (which is wired inside to the points).........The other wire goes to frame ground

If it were an Ignition switch for a battery powered coil ignition NOT a Magneto;

One wire goes to the coil, other wire to hot battery voltage and if the switch is ON it sends voltage down to the coil

Maybe you're right and some "expert" will weigh in??

John T
 
Hi John The Wiring Expert,

Yes, confirmed what you said. Toggle On/Off switch is grounded to frame, with hot wire to magneto.

Thank you!
Billy
 
You're welcome, thanks for the feedback. Im NO expert on that Magneto (never seen one up close even lol), although I have written for The Green Magazine plus given Seminar Workshops at several National John Deere Shows on Coil Ignition and Charging Systems plus Wico Magnetos, but they are quite a bit different. Still, the theory and kill switch operation is pretty much the same for any mag so my guess was right lol yayyyyyyyyyyyy

John T
 
BTK, I see that no experts other than John T has chimed in on this thread. John has been a resident electrical expert on this forum for many years. Perhaps few have additional info to offer.

As the owner of a 1951 WD, I can offer a couple of observations. The Fairbanks Morse X4B3 is not original to that tractor. It is the successor to the FM J4B3 which was original. The X is a direct substitute, superior to the J in a couple of respects and, in good condition, worth a large portion of what you may have paid for the tractor. I believe that you have both deduced the correct connection for those three wires, and I am not inclined to disassemble my J to confirm this. The X and the J have the points in the same location, but the fulcrum orientation is different.

Your tractor was originally 6 volts positive ground. Most upgrades to 12 volts are typically via inexpensive 12 alternator, which is most frequently negative ground. If you are judging by the identity of the battery, don't assume that a 12 volt battery in the box is proof that the charging system is 12 V +ve ground, especially if a generator with original cutout is still in place.

The On-Off toggle switch is likely a retrofit, as J's came with a grounding tang on the magneto body, but X's were supplied without it.

If you would like to receive a library of links & documents regarding FM magnetos, accumulated over dozens of hours scouring the web, include an e-mail address in your profile and I can send them to you over time.

stu
 
Stu,

Thank you for the information and generous offer of
sharing information on the FM mag. Yes, I am very
interested in learning more about how my tractor
works. It's all new to me. I would rather fill my
mind on magneto data than with the drivel on TV.

I did update the information on my profile.

Best,
Billy
 

We sell tractor parts! We have the parts you need to repair your tractor - the right parts. Our low prices and years of research make us your best choice when you need parts. Shop Online Today.

Back
Top