Ok so I have a bit of a problem here. I have a friend who has a gorgeous Farmall B. The same tractor his grandfather had that he used to ride on the rear axil as a kid. He’s done a beautiful job restoring it and its been in local parades for the last 10 years running just fine. A couple of years ago he started replacing the original light switch, regulator, and amp meter, but never finished it. As he’s getting up there in years and has had some health problems I’m trying to step in and help, although I’m not familiar with tractors. I’ve been reading through the forums on this subject and I believe that I’ve read and understand John T’s instructions for determining the cause of the problem. The problem is that after following the test and measurements the conclusion according to the flow chart is that the generator needs to be repaired or replaced. I did remove the generator and sent it off to a repair shop only to receive it back again with a call from the shop stating there is nothing wrong with it. So after retesting and coming to the exact same conclusion, I wanted to ask you the experts what do you think? Here is what I have and done so far.
Farmall B 6V positive ground
A terminal of the generator connects to the GEN tab on the bottom of the regulator
F terminal of the generator connects to the F tab of the regulator
BAT tab of the regulator goes directly to the (+) terminal of the amp meter
L tab of the regulator goes to the light switch and ignition switch
Extra wire (yellow) goes from the base of the regulator to the frame ground bolt where the + terminal of the battery goes
With tractor off, turning the light switch to “D” provides a ~10-amp discharge on the amp meter
With tractor off, turning the light switch to “B” provides a ~12-amp discharge on the amp meter
With ignition switch on (light switch to “O”) provides ~2-amp discharge on the amp meter
So, I believe that the amp meter is correctly wired and working as should
Measuring the voltage between the frame and meter I get 6.38V on both amp terminals
With tractor off, I run a jumper from the BAT tab of the regulator to the A terminal of the generator to polarize the regulator and I do get a small spark. (video link below)
With the tractor running at low idle, both contacts of the regulator spark causing no charge to the battery. (I’m assuming there is not enough output from the generator to cause the relay closure)
Increasing the idle causes, the relays to close and thus forces the amp meter to peg the needle to the discharge side. (video links below)
Shorting the F terminal to the frame produces no change
Shorting the F terminal to the frame and shorting the GEN tab to the BAT tab produces no change.
From the pictures and videos, I’ve provided, is it possible that the generator repair center didn’t know how to test?
One other thing. With the tractor, off and the belt removed from the generator, I can cause the generator to run like an electric motor by manually closing the regulator relay. Then if I remove the F terminal from the regulator, the motor with stop and spin in the opposite direction.
Video 1 https://youtu.be/pqPq18hjDYg
Video 2 https://youtu.be/qP_qGu-k9bQ
Video 3 https://youtu.be/Ir9kCbvRclA
Video 4 https://youtu.be/HYfFssZOgLk