1950 JD A wiring diagram

Maritimer · Aug 7, 2013

I'm redoing a JD A and am looking for a wiring diagram for it. Its a 1950 with a 12v system and a wico mag. It also has the 12v generator also. I found one on line somewhere but it had the distributor and coil.

Thanks for all your help. it will be greatly appreciated.

John T · Aug 8, 2013

Is this the diagram you were speaking of (late Model A with coil ign) ??? The battery and charging part of it would still be correct (unless tractor was modified??) HOWEVER as you well know since you have a Magneto instead of a coil ignition there are some minor modifications:

You do NOT obviously (as shown) come off any ignition switch and send battery voltage to the mag.

I cant say sitting here if your tractor has any sort of kill switch wire and On/Off switch up on the dash??????? Or maybe theres a small push to kill button on the mags side??? All I can say I already have DO NOT RUN A WIRE FROM AN ING SWITCH DOWN TO THE MAG TO SUPPLY BATTERY VOLTAGE TO IT.

Some Wico X Mags have a kill switch side wiring terminal on them and if its grounded out it kills the spark. On those its possible to run a wire off it to an ON/Off dash switch or key etc that grounds that wire when OFF but keeps it open (ungrounded) for ON

Maybe this gets you started???

John T

Pete76NY · Aug 8, 2013

Maritimer, I have a "49 A and a "50 B both set up like that; 12v and mag. I have a JD electrical manual and there is no diagram in it for that particular set up. I basically used the older 6v mag diagram as my starting point. Neither of my mags has the "kill" button, but the A has a dash mount toggle switch and the B has a key, both just ground out the mag, I am not near my manual, won"t be for 2-3 days but if you still need any diagrams hit me up if you can wait.

Maritimer · Aug 8, 2013

Hi john, thanks for the info. My mag does have a ground terminal on the side of it, and I presume that I can run a wire from it to the dash so when I turn the switch, it will ground out and kill the spark. So the black wire, i will bypass the ign switch and run it only from the regulator (L terminal) to my lights? And is it 12v pos ground?

Maritimer · Aug 10, 2013

Hi Pete, would you be able to send me a picture of your diagram that you used?

Thanks, its greatly appreciated.

Mike

Maritimer · Aug 15, 2013

So, would this still be a positive ground system? even though it has a 12v generator?

Tx Jim · Aug 16, 2013

YES JD didn't change to negative ground until alternators were installed.

1950 JD A wiring diagram

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