New Voltage Regulator at 15V?
The 15V is measured at the battery terminals. I'll poke around a couple different spots and see if there is any difference. The alternator has two field connections and the black heavy output wire. No polarity marking on the fields or in the diagram so I just connect the field wires to suit the wire length. From what I've found, field polarity should make no difference in a properly functioning system.
sounds good.
Correct. On the '70 up systems, the blue wire is the rotor's power source and it's voltage determines what the regulator does.
When system voltage is low, it connects the green wire to ground. When system voltage is high, it opens the connection, interupting flow which causes the magnetic field to diminish. In between IIRC it restricts the flow using a resistor.
Lets say the battery is 15 Volts above ground.
Its possible the Alternator output stud is also at 15 Volts, but the 'ignition' wire from the ballast to the alternator is at 14.3 Volts.
In which case the regulator is doing its thing correctly.
Since the drop in voltage must be between the main splice and the 'ignition' wire, this would indicate a resistance between the main splice and that wire.
When using an analog gage its easier to measure voltage drops with by measuring voltage between two points in the cirvcuit; as opposed to measuring voltage above ground. With a digital gage it still is useful for tracing because it eliminates voltage drops in the ground circuit.
Feel free to substitute 'run' for every place I wrote 'ignition.' Chrysler always called that the 'ignition 1" circuit but it's always had a branch to supply the alternator.