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12 Volt Conversion for 1940 9N?

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Larry Kastens

01-13-2020 18:45:29

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I bought a 12 volt conversion but the company did not include the directions. The kit has a one wire alternator, a 12 volt coil, a ballast resistor, and the necessary wires and brackets. Could someone point me to a simple wiring diagram that uses a four post starter solenoid? There are many diagrams online but I can not find any large enough to print that shows the four pole starter solenoid. Does a person need the old terminal block with its own resistor?
I also installed a starter button. What size should be the 12 volt wiring? Thanks to anyone who responds.

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01-14-2020 11:25:29

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 Re: 12 Volt Conversion for 1940 9N? in reply to Larry Kastens, 01-13-2020 18:45:29  
There are 2 configurations for a 4 post starter solenoid.

1. Voltage is applied to the S pin to activate the solenoid, it grounds through the mounting base. The I pin is connected to voltage when the starter activates. This is used in a 12 volt system with 6 volt coil and a dropping resistor. When solenoid activates 12 volts is applied from the I pin to the coil input, bypassing the dropping resistor and giving hotter spark for starting. You normally would not use this setup on an N tractor

2. The activating coil is connected between the S and I pins. Voltage is applied to one pin, ground to the other pin. One side would have the momentary activating switch. This was used on 601/801 series

Which configuration do you have?

The output of your 1 wire alternator would go to the ammeter/switch connection at the terminal block.

For a 4 wire solenoid you could adapt the diagram for 601/801. Search for a diagram.

I would be hesitant to give up the safety of the original interlock system on your tractor that prevents the starter from being activated with it in gear.

With a replacement 12 volt coil you would not use the extra resistor, but you should keep the original resistor.

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01-13-2020 20:14:01

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 Re: 12 Volt Conversion for 1940 9N? in reply to Larry Kastens, 01-13-2020 18:45:29  
ps: the white ceramic resistor supplied with the kit is not needed with a 12 volt coil.

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Larry Kastens

01-13-2020 21:04:47

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 Re: 12 Volt Conversion for 1940 9N? in reply to HFJ, 01-13-2020 20:14:01  
Thanks for that and the other comment. Yes, you are correct, I am using a different starter button.

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01-13-2020 20:11:58

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 Re: 12 Volt Conversion for 1940 9N? in reply to Larry Kastens, 01-13-2020 18:45:29  
a 1940 9N, or any other year 9 or 2N, did not come with a solenoid.

yes, u want to keep the OEM ballast resistor.

i'm guessing the start button u refer to is not the original neutral safety button by the gearshift?

we love pictures ;)

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Larry Kastens

01-13-2020 21:07:49

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 Re: 12 Volt Conversion for 1940 9N? in reply to HFJ, 01-13-2020 20:11:58  
Thus, is the original resistor needed on the terminal block?

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Tim PloughNman Daley

01-15-2020 05:35:26

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 Re: 12 Volt Conversion for 1940 9N? in reply to Larry Kastens, 01-13-2020 21:07:49  
The white ceramic "ballast resistor" in your 12V kit is NOT the OEM Ballast Resistor. It is recommended to use the OEM Ballast Resistor in the circuit when doing a front mount 12V switch over job. You also do not use the ceramic in-line 1-OHM resistor in addition if you have a 12V coil BUT don't assume -often aftermarket, Cheena-made units are mislabeled so test it first. The 1-OHM resistor is only used if you have a 6V coil. The 9N/2N 1-Wire starter motors did not have a solenoid. Are you confusing the roundcan cutout for a solenoid? Having the essential manuals is every bit as important as any tool you own. OEM 9N/2N Wiring, Ballast Resistor, 1-OHM external resistor, OEM roundcan cutout, and 6V wiring diagram. Go to search to get WIRING PICTOGRAMS by JMOR to see and download the 9N setup.NOTE: When switching over to 12V, remove generator and cutout, install 12V battery (GRP 25 or 35), 12V alternator, a 1-OHM ceramic in-line resistor only if using a 6V coil, not used with a 12V coil (recommended). It is important you get all the wiring correct before power is applied. If you have lights, test to verify they are 12V lamps otherwise you will let the smoke out if left at 6V.






*PICTOGRAM courtesy of JMOR


Tim Daley(MI)

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01-14-2020 05:49:45

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 Re: 12 Volt Conversion for 1940 9N? in reply to Larry Kastens, 01-13-2020 21:07:49  
99% of the responses on this board will be "yes", but I've been running a '39 with a one wire alternator, 12 volt coil and no resistor for several years. Reason -the original resistor was missing and I was in a hurry to get it running.

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