John deere 620 ignition

Jonpink17 · Oct 6, 2014

I have a 1958 john deere 620. It started perfect before I took the old battery box off, but I put a new box on and connected the battery with a negative ground. I pulled it and it wouldn't start. I noticed the wire from the battery to the ammeter was red hot after pulling it. I later switched the battery to positive ground and the wire arks really bad. Any idea to what is causing this??? Thanks!!
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buickanddeere · Oct 7, 2014

(quoted from post at 22:50:25 10/06/14) I have a 1958 john deere 620. It started perfect before I took the old battery box off, but I put a new box on and connected the battery with a negative ground. I pulled it and it wouldn't start. I noticed the wire from the battery to the ammeter was red hot after pulling it. I later switched the battery to positive ground and the wire arks really bad. Any idea to what is causing this??? Thanks!!
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Original charging system or has an alternator been added ?
If the original system is on the tractor. Has the voltage regulator cut out welded it's self closed ?
Which wire on the coil is connected to the ignition switch?
Has a Pertronix ignition system been added ?

John Deere D · Oct 7, 2014

Neighbour Lady was in the Field with her 620....positive ground factory ignition......every low voltage wire except the Battery leads burnt up! Yes the main selector switch on the dash as well as the Voltage regulator was fried. The power supply from thee STARTER contactor that supplies power direct to the coil only on start up was also fried!
So what caused the wires to burn? A year earlier I replaced the INTAKE and EXHAUST MANIFOLD. At that time I questioned the shaudy electrical workmanship on her 620? No she would not allow me to replace all wiring at that time. Pay now or pay latter.

Jonpink17 · Oct 7, 2014

Ok. I got the tractor to start but the wire still arks when connected to the battery. I noticed the ammeter needle goes way over to the negative side when the tractor is off, but when I start it the needle goes back to zero.

John Deere D · Oct 7, 2014

With JD 620 running DISSCONECT all wires to the voltage regulator..........now any change with the ammeter and the sparking of the wire at the battery?

John T · Oct 8, 2014

When it was started at the wrong polarity you could have fried the Voltage Regulator!!!

If (back at the correct + ground polarity) the ammeter goes to a high - discharge when its turned off, the VR's Cutout Relay contacts are likely welded closed.

BEFORE doing anything else and with the battery installed at POS ground I would polarize the genny,,,,,,,,,then I would remove the wire that goes to BAT on the VR (tape it don't let it short to frame),,,,,,,,,,,then start it and the ammeter may go some negative but there shouldn't be any high currecnt draws or smoking etc,,,,,,,,,then while running connect the wire back to BAT on VR and see what happens. If the genny still works it could possibly (don't hold your breath VR may be too long gone) charge then????????

The if you shut it off the ammeter swings to heavy - discharge you know the VR's cutout relay contacts are stuck closed.

You may well need a new VR and hopefully nothing else got fried???

John T

John deere 620 ignition

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buickanddeere

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John Deere D

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