Big mistake, changing to 12 volts

I think I made a big mistake. I changed over my John deere 420w from a 6 volt positive ground to a 12 volt negative ground. When I turned the switch on it only worked for seconds. Now the switch does not work. Did I fry something in the switch when I went to 12 volts through it.?? What do I do now ??? Any and all advice and help will be very much appreciated.
 
(quoted from post at 15:26:36 05/07/23) I think I made a big mistake. I changed over my John deere 420w from a 6 volt positive ground to a 12 volt negative ground. When I turned the switch on it only worked for seconds. Now the switch does not work. Did I fry something in the switch when I went to 12 volts through it.?? What do I do now ??? Any and all advice and help will be very much appreciated.

The switch should work with either ground and 6 or 12 volts. What was the total scope of what you did in changing from 6 volt positive ground to 12 volt negative ground? You mention the voltmeter started to work. 420s didn't have voltmeters. If you installed a voltmeter did you run a switched power wire to it and a ground to the other terminal? If you replaced the ammeter with a voltmeter and wired it in series, like the ammeter would have been wired, it likely burnt up, this loss of power to the switch. Just a guess from what you have posted.
 
Yes, I added a volt meter. I hooked one side to ground and the other side to a post on the back of the ignition switch that is hot when the switch is on and off when the switch is off.
I put on a new internal resistance coil and reversed the wires on the coil. Positive to negative and negative to positive. I put in a 12 volt battery and changed the positive from ground to negative ground. I hope this answers your question, and thanks for the help. I also hooked the exciter wire to the same post as the volt meter wire. Hot when the ignition switch is on and off when it is off.
 
I did not know there is a inline fuse feeding the switch. I will track it down tomorrow. I used one of the connections that is hot when the switch is on and off when the switch is off. I don't know what it feeds.
 
When the volt meter quit working. I checked the post that I had used for the hot wire and there was no juice there.
 
I also forgot to say that I added an idiot light. I ran a hot wire from the back of the switch to the light and from the light to the exciter wire.
 

You have not directly said you changed from a 6 volt positive ground generator to a 12 volt negative ground alternator, but adding an idiot light to the excite wire implies that. How/where did you run the battery and sensor wires for the alternator to?

Did you remove the old generator regulator and its related wiring? Do you have the optional key switch and the rotary switch (ignition and lights) or just the rotary switch?

Use the diagram M-Man posted to see that you have power to the key switch (if yours has one) and the rotary switch.
 
I just have the rotary switch. The only fuse I can find is the one at the top of the dash. I checked it and it is fine. BUT, I get no juice to the ignition switch. Is there another fuse that I have not found.??
 

From the drawing M-MAN posted for you, the dash fuse got power from the L terminal on the voltage regulator. From the fuse the power went to the key switch then the rotary switch. In your case it would go from the fuse to the rotary switch since you don't have the key switch. Do you have power coming to the fuse? Did you totally bypass the old regulator during your conversion so there is no power on the L terminal of the old regulator to supply the fuse?
 

As a test. Remove the wire from the regulator L terminal and try putting a jumper wire between the battery positive terminal to that wire to see if that powers the fuse. If it does power the fuse, try starting it. If it works, I suggest using a new wire to feed the fuse from the battery cable terminal on the starter switch.
 
Can't see why you would want to convert to 12V but to each his own. I have a 420W that is 6V and it cranks that little 2-cyl
engine over just fine. I did lose voltage to the distributor and it was a lose wire going to the fuse. Gave me fits.
 
(reply to post at 12:26:36 05/07/23)
Hi again, after all the help I got with my problem. I decided to call a mechanic and let him take care of the problem. The more answers I got the more confused I became. ( I am 79 and Easley confused ) Thank you all for the help I appreciate every one who tried to help me. thanks again
 

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