Series III Alternator

I am having fun with seriesIII alternator, I am on my second new one. I have just checked wiring again, after running the alternator for say 20miles, and find that the "S" wire is open circiut, I have run a replacement lead and now have 12v on it, but the alternator doesnt charge.
Can anyone tell me if running without this connection would damage the alternator. Also can anyone suggest what my problem could be.

Thanks

wtf is a 's' wire

I think that's the "S" connection is the Alternator battery sensing lead

Alternators work by dynamically adjusting the strengths of a set of "Electro magnets".
In this way when you do not require so much power the field is weaker and its easer to turn the alternator.
So by not connecting this wire to your alternator your alternator now has no reference and will either be
full on or full off depending on the regulator logic.
To be sure I would have to have a look at the cct diagram.

Hi clivees

Thanks for your reply.

You are right the S connection is the battery sensing lead.
It seems that the alternator has indeed gone to full off. I have attached a circiut diagram for the alternator, do you know how I can turn it on again?

Ok this is how it works

When the combined volts from "S" and "+" wires are BELOW a set threshold set by the voltage divider R1 / R2
the Zener diode "ZD" is effetely a open circuit and the transistors will be in the following states.
T1 Hard off
T2 Floating (Dependent on the current in "S")
T3 Floating (Driven by T2)

This will vary the field strength of the field winding "7"

This is all working correctly.

When the combined volts from "S" and "+" wires are ABOVE the threshold set by the voltage divider R1 / R2
the Zener diode is effetely a short circuit (Look up avalanche break down) and the transistors will be in the following states.
T1 Hard ON
T2 Hard off
T3 Hard off

This will turn off the field winding "7" and turn off the alternator

As to your problem I would start by looking at
Zener diodes ZD and AD ,AD is a protection diode against spiking on the field coil and if this was short you would not get a supply to the field.

But it may be cheaper and quicker to buy a new one.

Good luck

bloomin eck Clivees. dat almost sounds like yu nose wot yu is talkin abart. Is that a furst for lz?

I know i need to get out more often.