John Deere A | Testing the Magneto

[@jefframey1025]

I’m learning along with you , it’s nice when people share their wisdom with you

[@chrism.2231]

I would check continuity through the cap to start. Also, look for any carbon arcs inside of it that might be creating an issue. I have not played with magnetos a lot, but I agree the speed thing does not make a lot of sense to me. I have seen videos where people have clicked over once by hand and gotten zapped.

[@johnseavey6622]

You are doing everything back wards the mag needs to stand up vertically

[@farmboy3400]

You are turning it the wrong way. The thing you are calling a stop the other direction is the impulse. It is spring loaded. Turn it by hand against that stop. It takes a little force but it will go. A good mag will spark just buy turning it by hand past that impulse.

[@jazzerbyte]

I'm not an expert on this magneto, but that sounds right. It should give a strong spark when turning by hand. There's that 'clink' sound when the magneto sparks at hand crank speed.

[@HumbleAcres]

Thanks for this I will give it a try!

[@HumbleAcres]

Well you were right I spun it by hand and both pugs have a strong spark. Maybe the tractor just needs new plugs and wires?

[@farmboy3400]

@@HumbleAcres Glad I could help. I have had to work on a few of them.

[@johnseavey6622]

The seed from a drill is bad there is an impulse spring you only need to spin it by hand

[@dukeman7595]

Check the following from "Yesterday Tractor" it may help you with the specs. etc. : Re: Wico X magneto coil; test procedure? in reply to Todd Wiscal, 04-29-2006 22:23:08 Todd I can describe a procedure to use only an ohm meter to tell you if a coil is indeed BAD but it will not tell you if its necessarily GOOD. You need a regular high voltage coil tester for that cuz many common failures are due to high voltage breakdown and especially once up to temperature, which the low voltage ohm meter simple continuity checks will not reveal. This assumes its a Wico C or X mag NOT a Wico XB distributor....... NOTE: It still takes a decent quality ohmmeter to measure these low ohm values which should adjust/null out to zero with the leads shorted if an old fashioned analog type. A coil MUST pass at least simple continuity tests in BOTH the low voltage primary and high voltage secondary windings and NOT be an open, cuz if EITHER winding is open its BADDDDDDDDDDDD. PRIMARY If you remove the wire from the points leading to the condensor and any kill switch stud wires (if it has one) youre left with the coils low voltage primary wire on the points so if when the points are open or that wire is simply removed (best way to test) and you place an ohmmeter on it and case/frame ground (provided the ground lead is good and connected) you ought to measure maybe in the 0.4 to 1.0 or so ohms range. If its an OPEN circuit its bad or the ground lead isnt well grounded, they can get broke off or the screw grounding them be bad or loose!!!!!. SECONDARY If you place the ohmmeter on the coils side high voltage output terminal/button and case/frame ground, it ought to read 3000 to 7000 ohms or so and NOT be OPEN or else its bad or the ground lead is not grounded (see above). Also smell the coil for the burned electrical insulation smell test and/or see that theres no ugly oily sticky black gooooooooo has leaked out. If the coil passes BOTH tests and the condensor is NOT bad or SHORTED (condensors go bad you know) and the ground pigtail is grounded and its not a smeller or leaker theres a good chance its good so look for other problems like bad bushings causing the rotor magnet to drag and other problems. Another easy test is to replace all the wires on the points and put an ohmmeter there and to ground and manually open n close the points and the meter ought to read zero when points are closed (unless they are burned or putted or carboned or not closing) and the 0.4 to 1.0 when open. If she always a dead short even when open and the coils primary is not shorted, suspect a bad shorted condensor (try with its wire removed) or a kill switch wire (if it has one) or the kill switch stud is bad n shorted (if it has one and its wire is connected) try removing its wire n see what happens. DISCLAIMER these ohms values are not exact but should suffice for the purposes and limitations of the test I described, Duane or Glen could give you more exact and correct ohms values but that still depends on the particular model you have and the coil, REGARDLESS if its OPEN its baddddddddddddd. Ol John T in Indiana (NOT a mag repairman but have worked on mags and been to a goat show and calf roping in my day)

[@thomasknouse3934]

Take the wico C mag without a coil and add an external 12 volt coil. Run a wire from the generator side of the amp meter to a on/off switch. Then from the switch to the external coil. then from the coil to the kill thermal on the side of the mag.Then run your coil out put on the coil to the distributor on the mag. You have converted your mag to a distributor.

[@hipoboss]

Then you lose all the benefits of a magneto.

[@craigdeloach3976]

i replaced the ring gear on my dads old 41 model john deere LA . When i put it all back together i noticed there was no spark. The cap,rotor,condenser & points all look pretty new. I know the condenser is brand new. Spinning the magneto over with a drill i can see i have spark between the points. I tied the two spark plugs together like you have done here...and grounded them to the body of the magneto. No adjustments have been made to the spark angle inside the magneto. I still dont have any spark at the plugs. The wires look pretty old I wasnt sure if i could just get a simple two plug wire set for a v=twin lawnmower or if they might work I wasnt sure if this being an old 6 volt positive ground set up would it matter or not. I even have a shop manual i got from steiner parts, I cant seem to find much info about this old tractor.

[@laneclifner5089]

Did you ever figure out the issue? That’s exactly what mine is doing. No continuity through the cap… but I get it through the rotor.

[@darwingingerich6910]

You were spinning the mag the rong way

[@billyballejo2009]

Very interesting can't wait for the next video God bless u

[@rbtractorman]

ditto, go the other way and don't use the drill. snap it over by hand or screw driver.

[@edpickering8075]

Thank you....I have 2 B and 1 A....thanks......

[@HumbleAcres]

No problem. Glad it helped!

[@user-tn1hk6zm2freedom]

The mag does not need to be grounded to the tractor. The mag will fire the points all by itself. The spark plugs need to be grounded to the mag to fire the plugs. I see this is 3 years old so I figure you got it running? Here is why it is not firing. The metal bar that goes through the coil is not making good contact to the mag housing. There is rust on that bar and the surface it sets on in the mag. Clean them surfaces good and clean the clips that hold the coil down and it will fire.

[@dannykirby7425]

My 1940 John Deere H has set up for a year and now is not firing , I’m going to try what you said tomorrow. 👍

[@user-tn1hk6zm2freedom]

@@dannykirby7425 Clean it up good and it will fire.

[@dannykirby7425]

@@user-tn1hk6zm2freedom I cleaned it up and it fired right up. Thanks. 👍🚜

[@user-tn1hk6zm2freedom]

@@dannykirby7425 Your welcome.

[@MrGrxxx123]

Coil conversion

[@gerharddyck1987]

THE dog one side is not swinging that is why you only get a spark on one side.

[@chuck0837]

Can you clarify what you are saying here about the dog not swinging ?

[@bdouble3585]

Thanks for vid, save me some steps appreciated 🙏