Here's the quick and dirty, but take it with a grain of salt because I kept fighting with mine and finally switched to an alternator.
There are three relays in a generator type voltage regulator. The first one is the cutout, that disconnects the generator and regulator from the battery when the generator isn't spinning fast enough to do its job and keeps the generator from being a motor when the engine is shut off. This should close when you rev the engine. It should be open when the engine is off. It's the one with the big fat contacts on the left. You can test the generator by removing the belt and closing the relay. The generator will spin itself.
The second one is the current regulator, it has a heavy wire coiled around it and opens when the generator is maxed out with current and protects the brushes. If it's closed and its contacts are clean it is fine.
The third one is the one that does all the work, that opens when the voltage across is is strong enough to overcome spring tension and regulates the voltage by cutting the field on the generator. It is usually the one on the right end. It is also the one that tends to get burned and needs cleaning and re-adjustment often.
The adjustment procedure is shown in the manual. I burned mine out after a while because my wiring harness was rotten.
