farmall a charging system

I recently received a Farmall A from my Grandfather"s estate. It has previously been switched to 12 volt and has worked just fine in recent years. However, when I came to own this tractor, I found that I had to jump start it each time I wish to use it. I had the alternator tested and it works just fine.

Not knowing what else to do, I found an article about converting from 6 to 12 volt here on ytmag.com. Here"s the link:

http://www.ytmag.com/articles/artint195.htm

I figured that I could follow the instructions and included wiring diagram and rewire the whole charging system - which I did. When I finished, I went back over everything twice to make sure I had done everything correctly.

But, when I hooked the jumper cables up, the wires coming from the switch began to smoke heavily. Before I could remove the cables, the wires from the switch had melted between the switch and the ammeter as well as between the switch and the warning light/ignition coil.

I have gone back over everything I did and I am confused. How can I correct this problem?

Also, my tractor has the ammeter in a box just forward of the shifter. Below the ammeter in this box is a knob. I assume this knob controls the lights, etc.??

Thanks for your help!

Del

Sorry... here's the link...
The Article and Wiring Diagram I Used

The most common error is to install the battery backwards. All (with no important exceptions)are negative ground. If it is installed incorrectly it will smoke the alternator and wires. (the diodes in the alternator will condict full battery amps (hundreds) into an aparent short circuit. Not good. The attached diagrams will make sense and detail the components. Thank Bob, they are very fine work. JimN
Bob Ms wonderful diagrams

I agree with JimN below. Most likely you hooked the battery up backward. Unfortunately when you do this the alternator "looks" like a short circuit to the electrical system and things start to smoke.

The knob below the ammeter is the light switch. Depending on the year the tractor was built it may have been a combination light switch/generator control switch. But with an alternator conversion it's now simply a light switch.

BTW thanks Jim for your kind words!

Just rechecked the battery...

Positive connects to the starter and negative is grounded.

Any other ideas? Bad switch, maybe?

This article is very simple, yet very informative. I hope this will work on my 'A'.

Also, the wires that smoked and melted were nowhere near the alternator. The two that melted were the ones coming off of the switch. I used a simple toggle. And they are only melted from the switch housing to the point where they are joined to the wires running where they are supposed to go - the ammeter and the warning light/coil leads respectively. We're only talking about 2-3 inches on each side of the toggle switch. The alternator did not smoke and no wiring near the alternator melted. All of this action was no more than a couple of inches from toggle switch, which leads me to think bad switch.

Any thoughts?

Thanks

Del

If you have taken it apart, we can speculate only, but here are my thoughts.
The wire going to your simple toggle switch coming from the load side of the amp meter. It melted, so the power flowing through it was excessive. The switch was hooked to two wires, one going to the charge indicator lamp, and one going to the coil (or resistor then coil). Neither of these are heave loads, (the light is very low wattage, and the Ignition draws ~4 amps when not running and less when it is. Thus there is a short to ground.
I do not know where you places the indicator lamp, but it is often true that the typical lamp socket used is intended to ground the lamp when mounted. This means that if the lamp socket is attached to the metal of the tractor, that is the issue!. The lamp must be isolated from all metal when operating. Power can be attached to the bulb at the socket, but the socket must not touch the tractor. Other possibilities are that a wire was pinched or cut by a sharp edge and grounded.
If the heavy wire from the Alt to the amp meter is not toast, you are probably OK. Keep us informed on your findings. JimN