Smoking Generator

I could use some wiring help as I'm not sure why I melted my cable when pulling light switch.

I have a 12v battery that was not hooked up to the generator. I added a 12v regulator. I swapped to negative ground at the same time. I polarized generator by jumping A to BAT briefly.

- I have A from generator to A under the regulator.
- I have F from generator to FLD on the regulator.
- I have BAT from regulator running to ammeter.
- I have L from regulator running to light switch.

Behind dash, all left/right are from perspective of driver:
- I have BAT to ammerter on left, and from right ammeter connection a wire going to + on battery.
- I have L to switch on left, and on the right wires going to the lights.
- There is a black fused wire on switch connected higher up right side and going to, I think, right side of ammeter.

After all this was wired up, I pulled light switch and wire coming from L (yellow in photo) immediately started smoking and melted insulation. Lights work though.

Please help. This is not my forte.

I should mention this in a JD A.

I'm gonna GUESS your generator originally had a "cutout relay" rather than a voltage regulator and the yellow wire comes from a terminal on the light switch that gets grounded when you turn on the lights to make the generator charge more. (Was originally connected to the "F" terminal on the generator, rather than to the "L" terminal on a VR, as you have it now.

Parts catalog shows a setup as I describe was used on Serial # 477,000 through 583,599.

Does your serial number fall in that range?

<img src = "http://oi68.tinypic.com/2505fk9.jpg">

<img src = "http://oi63.tinypic.com/egemww.jpg">

SN 574050. I'm going to have to look at that with fresh eyes tomorrow. I wonder if it's as simple and swapping wires left/right in all places since I changed to negative ground. Assuming wiring is dash was correct to begin with (lights worked before I started messing with it, so something was right).

Sorry, I don't know how it was hooked up before. When I got the tractor it simply had the generator yellow and black wires cut at the generator. I put the 12v reg on to see if I could revive it.

Check the tag on the generator for Delco Remy numbers to identify the generator for certain, but unless it was changed to a 12 volt generator I believe it should be a 6 volt generator. As Bob posted it would have had a cutout relay, not a regulator. It should not be connected to a 12 volt battery, either positive or negative ground, or use a 12 volt regulator.

There's a chance when you ran that wire (from L on VR) to the light switch instead of providing voltage to power the lights it got connected to the resistor (or ground) that provided a ground to the gennys field post on an old manual Low High charge switch OR else the light dimming resistor. Those were used on older systems that only used a cutout relay and Low/High charge switch NOT a full fledged voltage regulator.

HOWEVER if that's a light switch ONLY (NOT a cutout relay system with manual Low/High charge) you may be connected to the light dimming resistor instead of where BAT input voltage should be.

Its possible to not use the L terminal on the VR and feed lights instead from the load side (same side that wires to BAT on VR) of the ammeter.

The L on a VR is to feed voltage to loads like lights and they can be fed from EITHER the load side of the ammeter (where wire from BAT on VR attaches) orrrrrrrrrr else L on the VR

I suspect the wire from L on the VR up to the light switch may be the problem. If L on the VR is incorrectly connected to a ground or a resistor that leads to ground that's putting battery voltage to ground and she will smoke n burn. Its supposed to power up lights or other loads NOT be direct or resistor grounded.

John T

Your tractor with a generator should be positive ground.

It doesn't matter as long as the generator is polarized correctly.

Thanks. The light switch I have is the kind that turns lights on/off and increases charge rate. Sounds like I should first disconnect L altogether and see what that does, and if that doesn't do it, replace the wire and connect to either FLD on the regulatory or directly to F on the generator.

I hope I didn't fry the regulator or generator doing this. I tested it before and got voltage from it when hand spinning, will have to test again. I forgot but I assume it's simply voltmeter on BAT and ground.

If you now have a full fledged Voltage Regulator you no longer wire the gennys field post to the light switch, but to the FLD terminal on the VR instead. The VR needs a good ground connection. Again the L on the VR can be ignored as long as the lights still get voltage from the Load side of the ammeter. What you CANT DO is wire L on the VR to ground or its smoke city. To be safe Id repolarize the Genny before you start the tractor again

The gennys output is across the armature which is the ARM post to case/frame ground.

John T

To polarize you should be touching momentarily bat to gen on the voltage reg with engine not running. Not A to Bat like you said.

(quoted from post at 00:58:00 01/22/19) To polarize you should be touching momentarily bat to gen on the voltage reg with engine not running. Not A to Bat like you said.

Click to expand...

"To polarize you should be touching momentarily bat to gen on the voltage reg with engine not running. Not A to Bat like you said."

When working with these old basic "automotive-type" charging systems, "A" and "GEN" are interchangeable names for the same terminals.

"[b:8401e8727b][i:8401e8727b]I pulled light switch and wire coming from L (yellow in photo) immediately started smoking and melted insulation.[/i:8401e8727b][/b:8401e8727b]"

Take a look at the diagram below.


Note that the light switch only has two terminals: one to the lights and the other one is shared by the regulator and ignition switch.

Take a look at the photo below of your tractor.


Note the large black wire to the lights, the yellow wire to the regulator, and the large black wire to the ignition switch.

Also note the red wire attached to the middle terminal on the light switch.

Remove the red wire attached to the middle terminal on the light switch.

Hope this helps.

The 20Amp Delco generator used on the 20 and 30 series are simpler now to wire . Plus they have much more output than the original . Yet they appear almost identical .

A brief update and thank you to everyone. I removed the yellow wire and so far so good. Still haven’t tried to start it though. Things take me awhile as the tractor is in another town...