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Farmall Super A, AV, 1939 - 1954

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SA Coil resistor

Tue Aug 09, 2011 11:46 pm

I just installed my new Brillman wiring harness (VERY NICE!) on my SA which had been converted to 12v. I must have told them something wrong, because as I was hooking it up, I realized that I didn't have the wiring for the almost forgotten coil resistor. I actually thought it belonged to the parts SA until today when I went through the photos and realized it was on this tractor.

Image

So my question is, is there a coil made that does NOT have the external resistor? Is it rediculously expensive? I just hate to add/delete wires from a brand new wiring harness. Anyone want to trade?

Thanks, Dale F

Re: SA Coil resistor

Wed Aug 10, 2011 1:55 am

Dale, the way i understand it, the points and condensor need the reduction in voltage to prevent overheating and thus early failure.

you will just be adding the one small jumper in your pic.

Dale

Re: SA Coil resistor

Wed Aug 10, 2011 6:07 am

Dale, to avoid tampering with your shiny new harness, just connect your resister in series between the coil & the dist. It doesn't care which side it's connected to.

Re: SA Coil resistor

Wed Aug 10, 2011 8:32 am

To answer your original question, an internal resistor 12V coil is available at NAPA for a little over $20. The number is IC14SB.

Re: SA Coil resistor

Wed Aug 10, 2011 9:19 am

A bit of clarification: In the photo above, one wire went to the coil (rear/left wire), and the other (forward/right) wire went around the front to the alternator on the left side.
Gary Dotson wrote:Dale, to avoid tampering with your shiny new harness, just connect your resister in series between the coil & the dist. It doesn't care which side it's connected to.

So where exactly do the 2 resistor wires go? In the photo the wire on the other coil terminal already goes to the distributor.

Dale F

PS The $20 NAPA coil may be the easiest solution...what's another $20 when I have spent 3x the value of the tractor on parts already!!! I just laugh when someone asks if I am doing this to sell it! !

Re: SA Coil resistor

Wed Aug 10, 2011 9:41 am

The resister is normally between the switch and the coil. in your instance, the same switch also provides power to the exciter, so they connected it at the alternator exciter connection rather than running 2 wires from the switch.

Re: SA Coil resistor

Wed Aug 10, 2011 9:53 am

Hmmmm...I should be able to figure this out, and maybe if I am standing there looking at the harness I will. I do know how to read a wiring diagram, but they did not send one with the harness...only numbered terminals with directions for where to connect them. I think I will draw a diagram, then perhaps I can figure it out.

So ultimately the goal is what? IF I have the rest of the tractor wired per Brillman's instructions, can I simply put this in series between the coil and distributor, as in between the left/rear coil wire and the dist? I will see just what wire is attached now to the OTHER coil terminal.

$20 is looking cheaper every question!

Dale F

Re: SA Coil resistor

Thu Aug 11, 2011 10:51 am

i personally prefer the internal coil route. simpler and cleaner. the resisters get hot and can be a source of failure.

Re: SA Coil resistor

Thu Aug 11, 2011 12:52 pm

Don McCombs wrote:To answer your original question, an internal resistor 12V coil is available at NAPA for a little over $20. The number is IC14SB.

Just spoke witht he NAPA guy, and one new resistorless-coil is on its way to the shop!!! Thanks once again for your advice and support! :big smile:

Dale F

PS Got the drawbar and rear rockshaft on so far today, plus some little piddling stuf!!
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