I have a THD with a 12 V 10 amp alternator. There are four wires connected to the alternator. Two black wires are connected to the rectifier YJ-58, which is simply to diodes connected to engine ground. The white wire (center tap of windings) from the alternator is connected to the battery via the amp-meter. The red wire from the alternator is connected to the regulator YJ-59, and the white wire from the regulator is connected to the battery via the white wire (center tap from alternator) and the amp-meter. My question is about the working principle of the regulator. I have checked the manual, and the check procedure tells that the resistance should be infinity between all combinations of the wires to the regulator, and also between the wires and ground (in both directions). This tells me that there is something more than a simple diode inside the regulator YJ-59. Buying a new expensive regulator seems a waste of money if I can easily build a new one. Can anyone tell me how the regulator works, and what’s inside YJ-59?