Trouble shooting 24 volt regulator/generator

I started the restoration of my ES 730D several years ago and am just now getting it finished. I've gone through just about every piece of it. I installed the Agri-Services wiring harness and overhauled the generator several years ago and bought the regulator at the same time. Now, several years later, I can't seem to get it to charge.
I'm confident that I've got it wired correctly. I've done several of these. The generator should be correct, but since I did it years ago, I just don't know for sure. I bought the four terminal regulator new.
When checking voltage across the A1 and A2 terminals, expecting 28 volts, I get nothing. The red dash light also remains on. Pretty sure it's not charging. I did polarize the generator before I started the tractor - between BAT and GEN/ARM. It sparked as expected but when I checked a second time, there was nothing.
Any suggestions? Start with the regulator then the generator? What are some good diagnostic tests without having to start swapping out parts?
I'm an electrical engineer, so I think I have a fair idea how the 24 volt system works. I didn't have any trouble when I did the same thing to my 24 volt 830 a few years ago.
Thanks for any advice,
Wes Wilkens

Wes,

Did you polarize the generator? The JD Service Bulletin on 24 volt systems may be of help. I can send it to
you as an email attachment if you send me an email through YT.

My email is open in Classic view.

Use a shotgun. Your less likely to miss.
Lol

Pete has you covered.

You should see a spark each and every time you polarize it, no matter how many times you do it.

If there's not spark, there's an "open" either in the generator, or in the wiring from the batteries to the regulator and generator.

The Service Bulletin "Mike" has to seen you will be invaluable in figuring out WHERE!

Wes, as a fellow electrical engineer I'm sure you understand what "polarizing" accomplishes and why indeed there should be current draw (sparkies) each time you attempt it. All you're doing is passing current through what should be continuous field windings powered via the 24 volt battery connection and wiring from them to the Voltage Regulator and Generator. No "sparky" means no current path and current flow nor accomplish the necessary correct polarization. First insure you're getting the 24 battery volts up to the VR and there's a continuous current path to and through the gennys field windings so they draw current to polarize and then enable the generator to fully function.

Perhaps when you first polarized and got the spark a weak resistive or loose connection opened up so the genny isn't operating ???

Once polarized and all connections in place so the fields draw their needed current hopefully the genny will function ??

John T

. Take the belt off the generator and the cover off the regulator .
Push the cut-out contacts together , they will spark a bit as the generator should now turn as a motor .
Now with the open the voltage regulator field contacts . The rpms of the generator should increase .

Thanks for all responses. Per John T and B&D, I just got the SM 2029 and intend to study it. I've done my 830 and overhauled both generators myself, but it's been a long time now since I worked on them and was just trying the lazy way to start the troubleshooting.
I will try what you've suggested before the study session. Thanks again.
Wes

Was the SB 268 I sent you any help?

I didn't know you sent it. Was it by private message? I am a member of multiple aviation forums that have private messaging but I'm not aware this one does.
If there is one, how do I access it?

I did check the field voltage at the VR and the generator. Both have 24 volts. I did see some paint on the generator brushes and thought that could be it, so I cleaned up the brushes and commutator to no avail. I'm going to try to run it as B&D suggested to see if it runs as a motor.
I am familiar with how the charging system is supposed to work but really haven't had a lot of time to dig into it yet. I'm guessing the issue is in the generator. I've done a really in-depth restoration and it's all painted now too. I've never had it running before tearing into it to know if the charging system ever worked. I went through the starter and generator several years ago and don't remember all the details now. The starter works great.
Wes