M Generator Test

[tmloos]

Hi,
I am trying to get my charging system working on my M. I installed a new Brillman harness and a new solid state cut out. The generator was "supposed" to be rebuilt. The tractor is running again but no charge in any switch position. I do see a discharge on the Ampmeter with the lights are on so I thing the gauge is okay.

I have tested the generator, grounding the F terminal, and connecting battery - to the A terminal. The generator does run, but when I disconnect the Field ground, the motor stops. Everywhere that I read, the motor should increase in speed when I disconnect the ground but it stops. Any advice what may be wrong with the generator?
Thanks

 

[John T]

When its running if you jump the gennys FLD post to frame ground does she charge????????????

If so the Low High light switch is bad or more often IT ISNT WELL GROUNDED. The gennys FLD must wire up to the switch and it needs a good ground to work.

Are you sure the solid state cutout (a diode I presume) is wired at correct polarity????????? Its supposed to pass current from gennys ARM to ammeter but NOT allow reverse current flow from ammeter to genny. CHECK THAT OUT

With FLD grounded if you apply voltage to gennys ARM post she ought to spin that tells you armature and brushes are likely okay. Then if you remove FLD ground she speeds up tells you fields are likely okay.

John T
John Ts Charging Troubleshooting

 

[tmloos]

John,
Thanks for the reply.

On the motor test, it does spin up and run, but stops when I disconnect Field from ground.

The switch has good ground, I cleaned up the surfaces and checked continuity before starting.

I can recheck the polarity of the cutout, but I paid attention so I think it's correct.

Thanks for your help