Hagen Brothers farms,Goodrich ND | The ignition switch on my 64 model 4020 has a white ceramic resistor built on the rear of the ignition switch. You would see a white ceramic tube like thing sticking out the rear of the switch.
The 3 ohm coil does not need a ballast resistor to operate on 12V,
The 1.5 ohm coil needs aprox a 1.5 ohm ignition ballast resistor placed between it and the 12V power supply. If your ignition switch has the resistor, wire around it to supply full 12V to your 3 ohm coil.
I had terrible luck with those JD ignition switches with the built on resistor, they (the built on resistor) were to high an impedence and dropped voltage to a 1.5 ohm coil too far, making for weak spark in the run position.
I finally cured that by installing a 30 amp accessory relay, connected directly to battery voltage at the starter, and routed through 12ga wire. I used the original ignition switch with resistor only to switch on / off my add on relay.
The electronic ignition now gets full voltage from the battery connection at the starter, switched by the accessory relay and voltage reduced by the recommended ignition ballast resistor recommended by the electronic ignition builder, because I am using the 1.5 ohm coil.
This made a huge difference in the spark quality and how the tractor runs. (starts when wet, luggs much better, never fouls a plug.) |
4020 electronic ignition
