1951 John Deere Model A Generator Issue

jdajason · Sep 8, 2015

Have a 1950 John Deere model A that I bought from my Grandpa. I am trying to hook the generator for the first time in ages. My dad said he was too cheap to buy a battery so they always parked it on a hill. So I have the wiring hooked up as shown in my I and T manual and when I connect the negative battery cable (positive ground) it sparks and I can hear it making a humming sound from the negative battery post and smells like something is slightly burning. The battery is a good one (started it all last winter and this summer no problems). Also, I am not hooking up lights to it nor have a key. I am kind of lost on what to do. Not sure what I am doing wrong or if that means my regulator is bad or what that even means. I don't think it should do that. Any help would be great. Posted some pictures of what I have, hope it helps. TIA!

jdajason · Sep 8, 2015

JDIH · Sep 8, 2015

Looks like you're using a 12 volt battery in a 6 volt system. Is it a distributor or a mag? If it's a distributor it's likely the coil you smell burning. As long as it hasn't been used in years, I would file the points in the voltage regulator.

JDIH · Sep 8, 2015

And it looks like your ammeter isn't hooked up and also at least one terminal on the regulator. Might take a little work to get it charging on its own

ndbjda · Sep 8, 2015

I would get a wiring diagram for the 47-52 A showing it with magneto. I betting that you have a stuck regulator and when you hook up the battery it is trying to make the generator run. A generator is basically a DC motor in reverse thus will draw amps/volts with stuck or improperly wired regulator. If it were mine I would do a complete new wire harness.

Todd Young · Sep 8, 2015

1951 A should be 12V Positive ground. The Alternator might be trying to motor when you hook the battery up on the voltage regulator is stuck.
I would rewire the tractor per the JD A diagram and change the voltage regulator...

-Todd

55 50 Ron · Sep 8, 2015

His pictures show a generator, not alternator.

55 50 Ron · Sep 8, 2015

a 51 A would be a 12 volt system. From the photos it is easy to see that the regulator isn't even in the system as there is no wire
connected to the BAT terminal so filing the regulator points won't do a bit of good. As others have said, "Best to put in a complete new
harness per a known diagram".

55 50 Ron · Sep 8, 2015

How do you know it has a magneto? 51 A would much more likely have a distributor.

55 50 Ron · Sep 8, 2015

It's obvious from your pictures that there is no wire connected to the BAT terminal of the regulator so the humming you hear when connecting
your battery cable can't be the generator trying to "motor" as there is NO CONNECTION to the generator. Until you connect the "system" to
the regulator BAT terminal, the generator and regulator are totally isolated from everything else in the system.

M-MAN · Sep 9, 2015

Let's try this one.

James Howell · Sep 9, 2015

Take a look at the diagram below.

Note the Armature lead (Key 3) located underneath the voltage regulator.

Take a look at the photo below.

Note the BAT terminal in the middle.

Take a look at the photo below.

Note the red armature lead that is connected to the armature terminal located underneath the regulator.

Polarize by using a jumper wire and momentarily jumping from BAT on voltage regulator over to A-Armature to get a small spark.

Hope this helps.

RLA · Sep 9, 2015

If Grampa coasted it all the time to run the tractor I assume it's sports a mag?

Mike M · Sep 9, 2015

If you have no other wires hooked up yet and just the battery cables get hot check where the cable hooks onto the starter. On those models it is VERY close to the rod you push down to start it and can easily touch if out of position. Also check for bare or pinched spots where it runs under platform and flywheel cover.

ndbjda · Sep 9, 2015

Without a battery and the Gen not hooked up the only ignition source would need to be a Mag. I have a 1950 A factory Mag never had a hole in the dash for a switch.

fixerupper · Sep 9, 2015

My 51 A had a mag when dad bought it new. He had a distributor put on a short time after he bought it.

jdajason · Sep 12, 2015

Thanks for all the replys. Have been busy
last few days. Made a mistake in the
original post. It is actually a 1950 and
yes it has a mag. I had it hooked up like
it was shown in the wiring diagram with the
wire going from the batt terminal to the
ammeter and then to battery. It made a
small humming sound that came from the
battery and was slightly smoking. I
unhooked wire for the picture. I will check
for a short in the wire which is possible
and the regulator.

bbeardb · Jan 21, 2019

Old thread, but reaching out to James Howell. Where did you connect L from the regulator? I'm having a problem. Can be seen here: https://forums.yesterdaystractors.com/viewtopic.php?p=8948857

1951 John Deere Model A Generator Issue

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