John Deere 40 S

Recently purchased a 1953 40 S. I had it on the trailer before I realized the battery was in negative ground. A closer look you can see the gas tank has been replaced and what appears to be paint damage from a possible battery explosion. I'm thinking this goes together with the fire extinguisher mount on the side of the hood. The question is what has been burned up from years of being wired backwards? What do I need to do to get it back correct?

"<font color="#6699ff">[b:654c4848f0][i:654c4848f0]What do I need to do to get it back correct?[/i:654c4848f0][/b:654c4848f0]</font>"

Take a look at the [b:654c4848f0]Lamps and Ignition Wiring[/b:654c4848f0] diagram below.



Note the 6 volt battery and generator.

Do you plan on using a 6 volt battery and generator "[b:654c4848f0][i:654c4848f0]to get it back correct?[/i:654c4848f0][/b:654c4848f0]"

yes I plan on staying 6 volt. From what I can see it looks correct which makes a little sense as when you turn the lights on the amp meter would go positive

Reversing the polarity will not cause the battery to explode. More likely the damage was caused when someone tried to boost the tractor with a 12 volt battery and did not make a tight connection which caused a spark and WHAMMOOO. Also, there are no sensitive electronics on that old JD 40 that would be harmed by reversing the polarity but, yes, the amp meter will read backwards which is why the meter jumped to a positive when you turned the lights on.

Just change the ground from negative to positive on the battery and you should be good to go.

If it has a generator is it properly polarized? Check with someone with more knowledge before you fire it up. Repolarizing is a simple process, sorry, i haven'r done for a long time -forgot how. If generator has been replaced by an alternator, all bets are off.

"<font color="#6699ff">[b:654c4848f0][i:654c4848f0]Repolarizing is a simple process[/i:654c4848f0][/b:654c4848f0]</font>"

Agree.

[b:654c4848f0]When and How to Polarize a Generator[/b:654c4848f0]

Polarization is a procedure which matches the polarity for the generator and the voltage regulator by permitting a surge of current to flow through the generator, correctly polarizing it.

Damage to electrical components can occur if polarities do not match.

Polarization of the generator should take place whenever any of the following events occur:
1. The battery is replaced or disconnected from the tractor
2. The generator is replaced or serviced
3. The regulator is replaced or serviced

If any of these events occurred, <font color="#ff0000">[b:654c4848f0][i:654c4848f0]do not start the engine until polarization is done[/i:654c4848f0][/b:654c4848f0]</font>. The polarity of the generator must be set to match that of the voltage regulator.

Make a jumper wire (14 or 16 gauge) and put alligator clips on both ends.

Polarize the generator by using the jumper wire, attach one end to the [b:654c4848f0]A Armature[/b:654c4848f0] terminal on the generator.

Take a look at the photo below of the generator.



With the other end, briefly for only a split second (or a spark occurs) tap the [b:654c4848f0]NEGATIVE[/b:654c4848f0] battery cable on the starter switch to get a small spark.

Take a look at the photo below of the starter switch.



Hope this helps.

should this be done with the tractor running or not?

thanks for all the info.

Always do this before you start the tractor.

thanks