Greetings, all: I have a '71 R75/5 that has what seems to be a vexing problem. The battery isn't charging, but my tests are mysterious. Using my manual, I ran the following tests: 1. I hooked up my voltmeter between the negative terminal on the rotor and the B+ terminal on the diode board. It read 14.5 volts once the generator light went off. So, it appears the alternator is fine. 2. I hooked up my voltmeter between the D+ (blue) wire on the voltage regulator and earth. It read 12.78 volts once the generator light went off. 3. I connected the two non-ground wires going into the voltage regulator. Voltage to the battery was still 12.78. I expected this, since test 2 had only 12.78 going to the D+ wire. 4. I tested the resistance at the slip rings. It seemed ok. There is no continuity to ground. Same for the stator, continuity between terminals, none to ground. My manual says the problem is the diode board. So, off to get another diode board. It arrives, i put it in, battery still not charging. Did the same tests above with identical results. I then tested both diode boards, and both are good. It sure seems like the alternator and board are good. I've owned this beast for 23 years, and it's never confounded me like this before. Am I missing something? Any input would be greatly appreciated. Thanks.