Mark LaBoyteaux modified a 60 Amp 1989 (or thereabouts) Mazda 323 alternator (same as Mercury Tracer alternator from same year) to use an external voltage regulator. Here are his modification pictures and text. I'm trying the same approach. The basic idea is to disable the internal power supply to the internal regulator, and then wire the alternator field brushes so one brush goes to ground, and the other brush goes to one of the terminals on the exterior of the alternator.

Mark and I both purchased our alternators from salvage yards for $40. A wiring diagram for the alternator can be seen in the Chilton's guide for the Mazda 323. A poor quality copy of the wiring diagram is shown after the alternator pictures.

In photo #1, Mark labeled the two screws you'll need to remove, and the two bridges that will have to be disconnected. (Tim's note: I believe the right bridge can actually be left connected, since it appears to do nothing more than connect a primary winding to an unused plug on the alternator case. I cut mine anyway, just to be safe\.)

In photo #2, Mark has already desoldered the top bridge, and started to snip the lower one. Mark says you could just go ahead and snip the top one too, if your soldering iron is unable to melt the solder (Tim did it that way, with a cutting wheel on a dremel tool).

In photo #3, the regulator is now removed from the alternator. Mark pointed out the solder "blobs" that will be jumpered.

In photo #4, Mark finished sniping the remaining pieces of the tabs from the regulator, and slid the plastic center piece off, this makes it easier to press the brushes back in place and slip the safety wire in to hold 'em down during re-assembly.

In photo #5, Mark has soldered the jumpers in place. As you can see, he used some de-soldering braid that can be purchased at radio shack. The one jumper that grounds the bottom brush, is not grounded untill the regulator/brush ass'y is screwed back in place in the alternator.

In photo #6, you can see how the safety wire is used to hold the brushes in place, so the rotor can be slipped in place without damaging the brushes. You'll be able to see in photo #8, how the safety wire sticks out the back of the alternator, so you can remove it after re-assembly.

Photo #7 shows the regulator/brush ass'y screwed back in place. Now you could use an ohmeter and check the lower (as oriented in the photo) jumper and it should read a short to the case (ground). Carefully re-assemble the alternator, when the three bolts that hold the two case halves are properly tightened, you should be able to spin the pulley with no drag or friction.

And of course photo #8 shows the safety wire sticking out the back of the alternator. Just pull it out, and the brushes will snap into place against the rings on the rotor. You should now be able to take the ohmeter and read about 8~10 ohms on terminal "L" to ground.

Try spinning the rotor while reading the resistance and it should go up slightly while the rotor is spinning.

Mark tested his by using 8 AA batteries to make a 12 volt source for the field current. Then he spun the rotor by hand and measured an output voltage on the main "B" terminal, or output from the alternator.