Motorola with no voltage regulator

Thoughts?  Joe

The regulator DOES NOT GROUND TO THE CHASSIS!!!!!!!!!!!!!!!!!!!!!!!!!!
The regulator grounds ONLY via the black wire to the alternator so that must be perfect. Case in point, I was testing my bread-board regulator circuit today (I'm developing new "guts" I can put into original Motorola housings) and a ground came loose and the voltage shot up to 17.5 volts. The ground was connected but loose, meaning the regulator was "sensing" a lower voltage due to the large voltage drop across the bad ground connection.

Alternator rotors are treated to NOT hold magnetism. Many will self-start once they hit about 1500 to 2000 engine RPM....... but don't count on it. 

As I've told folks before - if they want me to work on the alternator and want to be very certain both alternator and regulator are ok and work together, send me both. I can check both. 

I've posted proper regulated voltage here - which regulator is set to regulate at what voltage. 
I may be mistaken, but I thought the Prestolite regulator was mounted on the firewall - I've seen some AMC harnesses with connections back there that appear to be regulator connections.................

I have also posted what regulators work with which alternators - and the warnings about mixing them up. 

For example if you use an R2AM1, R2AM2, or R2AM4 regulator with a 1971 and later alternator (with NO isolation diode) you will over-charge by about a volt.
If you use one of the 8RB2005 or 2003 regulators with an alternator using an isolation diode, it will UNDER-charge by a volt.

Again - orange wire from dash ALT light goes to alternator and regulator. This excites the field and controls the light.

Yellow from ignition feed is a backup field excitation - in case the bulb is burned out the yellow will excite the field to get it charging.

Black is critical - from regulator to alternator, direct path, no stopping or connecting to anything else.

Green is also direct from regulator to alternator for the field. If this is loose you'll not get enough field current and it won't charge enough, or at all.

Once the alternator starts to charge, the current for the field comes from the regulator terminal on the alternator......... 

NEVER EVER EVER EVER disconnect the battery when the engine is running, PERIOD.

This doesn't show my whole test setup, there's other equipment involved, but here I'm testing a home-designed/home built regulator on a running alternator. I just got it working today............. hopefully to be able to rebuild old regulators using the original regulator housings....... It's in rough bread-board stage but it WORKED.

I need to make a change or two as it regulated a tad high but that's a simple change or two.

I made a sub-harness for him with the correct connections and all he had to do was connect it to a couple of wires in his harness and he was back to original system. 
The green wire to field and the black to ground are simply from regulator to alternator. The yellow goes from ignition feed to regulator, that was one connection he made, and the orange comes from dash ALT light to regulator, then down to alternator. So he had to make that connection as well. That was number two connection. 

His was a 1970 so the black ground was in the same connector as the green field wire, otherwise they were pretty much the same as 68 or 69. 

The yellow shown here has a connector for the coil, and the other end of the yellow needed to be connected at the I terminal of the starter solenoid. 
The orange needed to be connected to the harness orange with tracer which comes from the dash ALT light.

It's really that simple.

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Green from regulator plug to alternator field/brush spade (flat connector sticking straight back)

From the car's harness to the regulator:

Yellow from ignition feed to regulator plug

Orange with trace in car's harness under the hood goes to the regulator plug, then back out and to a connection on the alternator back side.

Knowing the model number of your alternator, or just if it's a 35 amp or a 55 amp, we can get totally specific and show exact connections on the back of the alternator.