I can't get a charge to the battery in my 77 280. I have a new battery, altenator and regulator. With the motor running I put a voltmeter ( Fluke series 3 multimeter ) and get no reading. I have taken it to the parts store and have had it tested in the car several times with it showing no charge going to the battery. I took it home did the A to F test with the voltmeter and got nothing. I took it out went to the parts store and it bench tested good. At this time I got a new battery and put them back in the car. Still no charge to the battery. Put a new regulator in still no charge to the battery. Did a continuity test on the WR conection from the alt. to the WR conection at the regulator. Did the same with the WR conection from the regulator to the + on the battery. Both showed continuity. In my 75 factory service manual it says to test the N terminal from the alt to the N terminal at the regulator for continuity but didn't clearly say to do so with them hooked up or not. It said if there was continuity there was a problem in the system but didn't say where to start. I checked the N terminal wire with it being unhooked at both ends and there was continuity. Also when I have the motor running the red light on the voltmeter is always on the needle never goes positive but does go negative when the motor is started and more when the lights are turned on. Any ideas where to go from here?

aren't the later Z alternators internally regulated?

The 280zx are

Have you checked fusable links?