M Spark ?

Have converted 6v to 12v M. Have power to coil, no power out of coil to distributer. Tried new coil, new wire from coil to dist, still nothing. Any ideas

Are you talking about the primary or the secondary has no power out?

Which coil wire is new, primary or secondary?

Is the distributor shaft turning?

Are you by chance testing the primary with a test light while the points are closed? If so, it's gonna show "no power".

Allan

If your points are bad that could be your problem or you wired it wrong etc. I would pull the distributor cap and open and close the points by hand. You should both hear and see a spark at the points. If you do not then the points are bad or you have a short in the system between the coil and the points

There should be voltage on the coils primary (small input terminal) anytime the ignition is on butttttttttt over on the coils other little small primary (to distributor) terminal theres no voltage when the points are closed. Of course, if you removed the little primary wire from the coil to the distributors side (to points) and turned the ignition ON then there would be voltage on BOTH the coils small terminals (since closed points no longer in circuit) UNLESS THE COIL IS BAD AND HAS AN OPEN PRIMARY WINDING. If you put a test lamp on the coils small to distributor terminal and turn the ign on n crank her over, the lamp should flash ON (when points open) and OFF (when points are closed).

Run my Troubleshooting Procedure should help diagnose the problem, but remember when the tractors just setting there and you turn on the ignition I WOULD NOT expect any voltage (to ground) on the coils little output to distributor terminal because the closed points will have that direct to ground

Im talking the low voltage (coils little + and - terminals) coil primary here NOT the HV secondary.

http://www.ytmag.com/cgi-bin/viewit.cgi?bd=farmall&th=5745

John T
John Ts Ignition Troubleshooting

Allan, I hooked a test light on the terminal of the coil that has the wire coming from the resistor and have power, this is the positive terminal on the coil. I hook the test light on the negative terminal of the coil, which has a wire that runs to the distributer. No light. Can you clarify for me what you mean by primary & secondary, I'm kind of tractor illiterate. Will double check but thought distributer was turning alright. Thanks didn't know about no power with points closed!!

(quoted from post at 17:43:05 10/28/10) Allan, I hooked a test light on the terminal of the coil that has the wire coming from the resistor and have power, this is the positive terminal on the coil. I hook the test light on the negative terminal of the coil, which has a wire that runs to the distributer. No light. Can you clarify for me what you mean by primary & secondary, I'm kind of tractor illiterate. Will double check but thought distributer was turning alright. Thanks didn't know about no power with points closed!!

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The primary circuit is the battery voltage circuit. It starts at the battery and runs through the ignition switch, resistor, coil, condenser, and points. The secondary circuit is the high voltage circuit starting from the coil and also includes the cap, rotor, wires and spark plugs.

When you turn on the ignition switch:

Juice will flow from the negative side of the battery, thru the switch, THRU THE PRIMARY side of the coil, out to the points and back to the positive side of the battery thru the tractor's ground strap.

This is the primary circuit and it sets up and magnetic field inside that coil around it's core.

Now, when that magnetic field 'quickly' collapses (the points open, breaking the circuit) all he!! breaks loose inside that coil.

It causes an INDUCED charge at the coil's SECONDARY windings (internal), which are physically attached to the coil's tower. These secondary windings are multiplied to step up this secondary voltage.

This secondary high voltage at the tower has to go someplace, so it is routed from the coil tower, via the coil wire, to the center of the distributor cap, then inside the cap to the center point of the rotor, thru it and out to whatever terminal inside the distributor cap that the rotor happens to be pointing at during that particular instant.

On out the cap, plug wire and it then jumps the electrode at the spark plug to complete the circuit and cause the ignition spark (fire). :>)

The reason you don't see the test light glow at the distributor side of the coil's primary is because those points are closed.

Electricity flows to the path of least resistance. It's easier for it to just go to ground inside the distributor rather than do all that work of lighting your test light. :>)

Reach in there and open the points with a screwdriver and your light will then glow. When you do tho, that coil tower is gonna fire. :>)

Allan

A light there on the output side of the coils low voltage primary shouldnt normally light up because the points are usually closed which takes the voltage to ground i.e. NO LIGHT (SEE ABOVE). The LV primary is between the coils little + and - terminals. One end hooks to the ignition switch via any ballast resistor while the other end hooks to the distributor and its points to ground when they are closed. A test lamp on the coils lead to the distributor needs to flash ON when points open but off when closed and if the engine is cranked over you can see it flash on n off. My procedure above will diagnose your problem.

John T

Gentleman, I would like to Thank You for all your help! John T, Allan in NE, ESPECIALLY APPRECIATE your advice and input. Found condensor wire terminal was grounding out on inside of dist housing, John T diagnostic sheet is what led to the repair, The mighty M is back up and running! Would anyone happen to know where I could get a wiring schematic? Have factory wiring harnesses and would like to install. Might need some advice on that also when time comes to install.