In Reply to: 6V Polarization posted by Mike on January 28, 2019 at 14:44:38:
The polarization method is different on them because it matters how the A and B circuits are grounded. The fields are grounded are different. Only the very first 9N-10000-A unit, a 2-wire/2-Brush, 'B' Circuit Design unit, 7 AMP output, and which used the 9N-10505-A special Voltage Regulator, and the FAC-10002 NAA unit, a 3-Wire/2-Brush 'B' circuit Design, 20 amp output, used Ford Tractor generators that had the 'B' Circuit Design. All others were 'A' circuit designs. With the 9N-10505-B cutout you polarize by arc-sparking the two terminals on it with a jumper wire. BTW, if you have an early 9N-A generator and do not have the voltage regulator for it, you can use the FAG-10505-A VR, but will need to modify how its mounted. Some later generators did have the barrel terminals marked -see picture. I'd say if you can't determine from the outside if a stud has or is missing the insulated rubber or phenolic washer or not, you will have problems. An internal inspection is need like JMOR says, but if you don't know what to look for, take it to a starter repair shop, they'll tell ya.