All I know about the 60amp internal regulator is I also have it. I think this old thread shows the wiring diagram that is implemented with Dave Irwin's upgrade.

240z alternator upgrade (instructions w/ pictures) - Electrical - Classic Zcar Community

interesting find.

I checked the voltage regulator cap that you must install when you use an internally regulated Alternator. The 4 pins resistance was as follows. The two pins OL had a very dark patch on the back. I need to find out if there is a diode in there.

6 minutes ago, Zedyone_kenobi said:

interesting find.

I checked the voltage regulator cap that you must install when you use an internally regulated Alternator. The 4 pins resistance was as follows. The two pins OL had a very dark patch on the back. I need to find out if there is a diode in there.

Try swapping the leads around where you got the open line. Diodes will block a resistance reading on a meter if you have the leads reversed.

okay, there is a diode in there, now I need to see what it would mean if the diode was in fact bad, and what that failure would manifest it self as

The two ways a diode can fail: Open or Closed.

Open:

Detection - You will see infinite resistance (OL) no matter what orientation you use with your meter leads. (Always try both directions.)

Result - The alternator won't charge.

Closed:

Detection - You will see zero (0) resistance no matter what orientation you use with your meter leads. (Always try both directions.)

Result - The alternator will charge, and the car will probably try to keep running with the key off since this will backfeed the ignition circuit.

copy, that, I just read my new multimeter has a diode testor function. I will give it a go when I get home. Great Advice as usual SteveJ!

Okay, I went into the electrical lab at work and borrowed a Fluke.

with the Multimeter on Ohms,

with the leads going red to black (left to right) on the two pins with the diode the Resistance is 23M Ohms

with the leads going black to red (left to right) on the two pins with the diode the Resistance is 1 M Ohms

I then switched the Multimeter to Diode Tester.

Red to black or black to red the Multimeter read OL.

That would indicate a failed diode to me. Wouldn't you agree, @Captain Obvious ?

The other components, the rest of the system overall, could be tested by bypassing the diode. A simple jumper wire or alligator clip could do it. Probably have to kil the engine by pulling the coil wire.

Then - how to fix it. What type of diode, how to solder or crimp? Or just buy another from MSA.

I already have another MSA alternator kit coming from MSA as we speak. It will be here in a few days. When I was just SURE it was the alternator I ordered one. But now it may look like I have a spare. It will come with the bypass clip for the Voltage regulator and I will swap it out then. If I had a spare diode laying around I could just solder up one with clips, but I am pretty sure I do not have one.

So, while the failure seems possibly diagnosed, lets talk about why.

What makes the alternator stop charging if that diode burns out. I have been looking a LOT at a 72 wiring diagram (I do not have a nice color 71 Z wiring diagram). I am trying to find something that looks like a feedback loop with a sense input, internal regulation and finally, output happens. I assumed the white wire with the red stripe coming out of the back of the alternator was the output voltage back to the fusebox and battery respectively. Is the T connector used in the feedback loop which tells the alternator to 'activate'

The Dave Irwin adapter converts one of the 71 wires to an "L" wire. Here's a schematic from the 1978 FSM. 1978 was the first year of the internally regulated alternator.

Interesting (to me), I just noticed that there is a resistor inline with the charge lamp. In the past I think I've seen discussions about what happens to charging if the lamp burns out. Apparently, nothing. Charging still happens.

In your case, when the diode opened, there was no current through the stator coil. No magnetic field was produced so no charging happened.