Alternator Testing

Hoping to get some ideas on my backup alternator problem. I have a switch on the panel that works the backup alternator. I have a B&C SD20 alternator and a B&C SB1B-14 regulator.

They alternator doesn?t appear to be producing any voltage when I switch from alt 1 to alt 2. I am not sure if it is the alternator or regulator.

Is there any way to test each to determine which might not be working?

Thanks
Shawn

Here is a TROUBLESHOOTING GUIDE.

I had a similar situation. Make sure you are turning at least 1800 RPM on the engine. That alternator does not produce power below 1800 or thereabouts. Can't remember the exact RPM but it was in that neighborhood