follow up on earlier JD B mag removal.

Thanks for the confirmation on how to remove the mag.Couple of you mentioned to check spark after the tractor quit. We have done that it is weak at best. Some mention the coil.I was thinking the coil is inside the mag. The plug wires come right to the cap on the mag. It dont have a coil (as I would recognize it). What would I be looking for? I picture a coil being a black tubular thing that mounts near the mag or distributor that has a plug wire going to the top of it.It is usually held in place with a metal band.I need more knowledge, I guess. Anything will be appreciated. Thanks again.
MIKE

There is no "coil" like a battery/distributor ignition. Inside your mag is a set of points, a capacitor (little silver tube,) and the remainder of the mag is a high voltage generator. That's what that thing with the multiple leaves of sheet metal is. All visible when you remove black bakolite cover with the 4 small screws in the front.

There is no "coil" like a battery/distributor ignition. Inside your mag is a set of points, a capacitor (little silver tube,) and the remainder of the mag is a high voltage generator. That's what that thing with the multiple leaves of sheet metal is. All visible when you remove black bakolite cover with the 4 small screws in the front.

I'm not sure what a your JD mag looks like, here's a Wico mag off a twin cylinder garden tractor and it shows the coil in it. Hal
PS: That brown item on the right is the coil.

YES A magneto indeed has a coil inside, how else you think it steps low voltage up to several thoudand volts necessary to arc current across a spark plug gap DUHHHHHHHHH

Its visible in the picture El Toro posted with its visible Wico lettering.....

It doesnt look like a typical tall thin can coil thats used on coil distributor ignitions, its more circular (actual windings) and has an iron core that goes through its center. It has a low voltage primary winding in the points circuit and a high voltage secondary winding whose output goes to the distributor rotor and eventaully via plug wires to the plugs.

If its a Wico X mag you see it if you remove the cap and its HV output button/terminal is obvious and where the caps lil springy contactor mates up.

If a mag is working correctly the spark should be a brigh visible blue and NOT any faint thin wimpy yellow spark.

Typical mag problems are burned or incorrect gapped points or a bad condensor or a bad coil.

John T

The picture El Toro posted is what the coil looks like on Wico C or X magnetos. YES INDEED a magneto has a coil, its used to step up low voltage primary voltage to several thousand volts necessary to arc jump current acrosa spark plugs gap.

The voltage is generated and gets induced into the low voltage primary winding of the coil by the passing of a magnetic rotor past it. Yes thats electromagnetic induction (a dynamo) but a coil is still necessary to step up the low voltage induced primary voltage to the thousands of volts to fire a plug.

Soooooooo a mag has points,,,,,,,,condenSor,,,,, and a coil. Laminated iron is used to serve as an improved conductor of magnetic flux to increase coil efficiency and electromagnetic induction

Hope this helps yall understand that A MAGNETO INDEED HAS A COIL

John T

John; Can you explain how the laminated iron conducts the flux better than a solid piece?

Gets deep, has to do with 'eddy currents' and efficiency. Maybe you can read up on them on google. Forgot most of what I learned. joe-

Teddy, GREAT QUESTION, I knew it to be true but its been toooooooooooo longggggggggggg for me to explain (I graduated EE wayyyyyyy back in 69) so heres a copy n paste off Google which tells it much better then I could...

"""

Because iron is a relatively good conductor, it cannot be used in bulk form with a rapidly changing field, such as in a transformer, as intense eddy currents would appear due to the magnetic field, resulting in huge losses (this is used in induction heating).

Two techniques are commonly used together to increase the resistivity of iron: lamination and alloying of the iron with silicon.

Lamination

Typical EI Lamination.
Laminated magnetic cores are made of thin, insulated iron sheets, lying, as much as possible, parallel with the lines of flux. Using this technique, the magnetic core is equivalent to many individual magnetic circuits, each one receiving only a small fraction of the magnetic flux (because their section is a fraction of the whole core section). Because eddy currents flow around lines of flux, the laminations prevent most of the eddy currents from flowing at all, restricting any flow to much smaller, thinner and thus higher resistance regions. From this, it can be seen that the thinner the laminations, the lower the eddy currents. """"""


Makes sense to me

John T

Thanks for the help. As I had mentioned before this is all new to me. If the questions I ask are offensive or seem idiotic to you please spare me the sarcasm! I am triing to learn and have no where else to go. I come to this site because there are so many knowledgable people that are happy to share. Please keep that spirit. This is a great site.