Solid State Regulator/Rectifier. Which wire goes where?

Factual Questions
1

I’m helping my FIL get the wiring in his scooter sorted so that it charges the battery while running. The generator is generating like it should and putting out 30 VAC at idle. That 30 VAC goes into a little solid state box with 4 male spade contacts. The purpose of the box is to rectify the voltage from AC to DC, then to regulate it down to about 14 VDC to charge the battery.

This is an odd brand of scooter and I was having trouble sourcing the original rectifier. But, having recently upgraded the old selenium rectifier and regulator on my vintage motorcycle, I knew where to get a regulator/rectifier capable of doing what I needed done.

At this point, I had assumed that the 4 wires going to the plug on the scooter were a 12VDC wire going to the battery, a ground, and 2 AC wires coming from the alternator. The unit I wanted to use has 2 AC inputs, 1 DC output and a ground.

The plastic plug on the scooter wasn’t the right shape to plug into the new unit, so I pulled the female spade connectors out of the plug so I could plug them into the new unit one at a time.

This is when I discover that the scooter has a 6 pole alternator, and there are 3 AC wires going into that plug and 1 DC wire leaving it.

I did a bit more searching, finally talked to the right guy and found the origninal regulator/rectifier for the scooter. So, I just gotta bolt it on and plug it in - easy peasy!

Except, I don’t remember which wires came out of which position in the plug. The new unit isn’t labeled. I can test the wires coming from the bike and know what each one does, but the real question…

TL: DR Question.
On a solid state regulator rectifier with 3 AC input and 1 DC output, is there anyway to test the four male spade connectors to determine which one is which? I have access to voltmeters, ohmeters, and ampmeters - but I don’t know what’s going on in that box or how to test.

Any ideas?

2

I would guess this is a three-phase rectifier, like so.

Except, it this case, one of the wires is connected to case ground.

So, with your meter set on “diode” on the Ohms range, you should be able to determine which lead is common to all three diodes - they will all read more-or-less the same from on terminal to the other three.

ETA: mark each terminal 1,2,3,4

Then make a chart of the resistance from each terminal to every other one, in both forward and reversed leads. From that, you can figure out where the diodes are attached.

3

I would guess the same. And, since the unit has a metal case that is bolted to the scooter’s frame, that’s a valid assumption that the case is ground.
The truth of the matter is, I only care about what output is the 12VDC out from the unit. The other three are interchangeable.

So, if I found the one lead that has the same reading between it and the other three, that’s the 12VDC out? Correct?

It almost seems too easy!

Thanks!

4

Correct.