Antique Tractors Forum banner

1 - 4 of 4 Posts

·
Registered
Joined
·
14 Posts
Discussion Starter · #1 ·
My brother has a JD 50 tractor that I've had to replace the resister to the coil, 3 times now.
Can someone tell me what might cause that to happen?
From what i can tell from the wiring diagram I've seen, its wired so that it gets 12 volts to the the coil when the starter is operated. Once the operator lets off the starter, that circuit is broken and it goes to the circuit with the resister in it to run on (I think) 6 volts. If that's correct, why couldn't the resister just be eliminated? Or would that 12 volt continuous circuit be to much for the points and condenser to handle? Or would a 12 volt coil with an internal resister work to eliminate the external resister?
Something is going on I am overlooking or don't understand. Some freindly advice here would be greatly appreciated!
 

·
Registered
Joined
·
57 Posts
You would not want to eliminate the resister because that is what saves the points from early demise and require replacement more often. A internal resistor coil will work but it will not give the 12 volts spark that you need on starting.

I don't have the wiring diagram but you should have a wire coming from starter solenoid to coil which is where the power (12) to coil gives the hotter spark to spark plugs for starting. When running the power comes from ignition switch to resistor to lower voltage through the points for less wear and longer life.

Resistors fail because of heat and high voltage supply. I would start by checking the voltage of tractor while running.

On a personal note my Dad had a 50 that left him stranded one too many times. He traded it off rather quickly and got the 520 which I grew fond of.
 

·
Administrator
Joined
·
4,252 Posts
I agree with Modeere, I wouldn't change anything. I wish I could give you an exact answer,
but I would clean every wire connection from battery to distributor. If it needs it or not..
I have had similar problems with condensers and resistors burning out, and that's what fixed both after several days of "try this next".
 
  • Like
Reactions: Modeere318

·
Registered
Joined
·
14 Posts
Discussion Starter · #4 ·
Thank you for those replies! Some good suggestions and new leads on fixing that problem. My brother lives about 2hours south, so it will be a while before I get the time to get back to work on it. The tractor isn't running presently, I've got some starter problems to address first. But once I get that figgured out I will definitly be doing what has been suggested here. Thanks
 
1 - 4 of 4 Posts
Top