Replacing External Voltage Regulator Alt
 

Who has replaced the external Voltage regulator Alt with an FC Style?

Any tips or tricks?

I'm interested in the response, as I'm planning on doing the same thing. I wouldn't think there's anything to do, as the regulator is internal to the alternator.

I've done it a few times. You need to locate the wire that is switched on whenever the key is on, and the wire that goes to the 'G'/gen/alt light in the dash. Once you determine those two wires, splice them into a T shaped connector (you can scrounge these from the rat's nest and other places) and plug it into the alt. The rest of the hook up process is the same. The adjustment bracket may be a little different on the earlier models, but should still be useable. The bolt length and spacer are specific to the alt type; I believe the break was '83 and older and '84 and newer.

Note: I don't recall which wire in the T shaped connector does what. Someone around here probably knows. Perhaps mar3.

Been a while since I looked at my '79 (since I sold it :-( ) but the external voltage regulator does a lot more than just controlling the charging system. It also sends power to the electric choke magnet and other odds and ends. I also discovered that the wire for the charge light is intended to open a relay inside the regulator to turn off the charge light. So, instead of grounding the charge light, that wire sends 12V to a relay. It's the same for the internal regulator version, just the relay is AFAIK in the instrument cluster. I learned all this the hard way while wiring the Abomination.

The 'leg' of the T is the 12V exciter wire from the ignition switch (which really should have a diode to prevent voltage feedback into the ignition circuit) , the 'cross' of the T is the 12V output for the relay I mentioned.

All you need is a an ignition wire. yeah, one wire that has voltage with the key on and hook it up as shown below.

Attachment 719331

Woops, need to correct my terminal information. The 'cross' of the T gets power from the ignition switch, this is the top wire in wackyracers' picture.The 'leg' of the T puts out 12V once the alternator is charging, that's what runs the choke relay etc. That's the lower wire in wackyracers' picture, the one that's not connected to anything.

here

I had hooked up my rx3 racecar and a rotary truck with a wire to the starter soleniod through a diode. When you cranked the engine it excite the field. Once turning it stayed energized by itself. The diode kept it from backfeeding and keeping the started on. Most people I tell this to can't seem to get the concept though. It is still working on my old car that I sold along time ago.

Yes and No.

On pre-81 RX with 81+ alternator, unplug the voltage regulator but you need 2 jumper wires, and mod the 6prong alternator pig tail. With that you can still use the choke. Check out how I did Ray's RX-4 and Dave's SA. But since most of us are running modified carb, this is a waste of time . Its easier to just find an Ignition Wire to trigger the alternator's "Field" terminal.

I recently put a 13B-RE Cosmo engine in my RX3. I am using the alternator from this engine and noticed a small problem. When I turn the car off I get a 1Amp drain on my battery through the charge wire. I connected terminal B to the existing charge wire and terminal S to keyed power, as labeled in Islandsnow's figure. Why is there a voltage drain? What is the fix?

Is a diode the only answer? Anyone know of a good diode to use?

Found it
 

Im using S5 altenator in my FB. one of the wires is connected directly to "B" terminal while the other is hooked up to my the stock pigtail for meters etc etc.. I havent noticed a power loss at all and I dont even use a diode. And yeah, to the 1st gen section @archieve There was a thread on it.

https://www.rx7club.com/1st-gen-archive-71/electrical-s5-89-alternator-install-into-1st-gen-528440/

Thanks, that's exactly what I was looking for.