Mike S is right. These voltage "stabilizers" are commonly referred to as
three-pin regulators. There is an input pin, a ground pin, and an output
pin. As Mike S says, the middle pin is also internally connected to the
mounting/heatsinking tab that has the bolt going through it. It's not at
all uncommon to make the ground connection with the tab. Once that's
done there's no reason to wire to the middle "finger." And, as Mike S
also says, these regulators will not provide regulated voltage unless
all three connections have been made. If the ground pin (or tab) is not
connected, you'll likely get the same voltage out as you're putting in -
unregulated 12 to 14 volts, roughly. If the input pin is not connected,
you'll get nothing out of the regulator. If the output pin is not
connected -- well, sorting that out is left as an exercise for the
student. I'll need everyone's answer on my desk before tomorrow morning
if you expect a grade.

--
Mike "Rocket J Squirrel" Elliott
71 Type 2: the Wonderbus
84 Westfalia: Mellow Yellow ("The Electrical Banana")
74 Utility Trailer. Ladybug Trailer, Inc., San Juan Capistrano
KG6RCR

On 3/24/2008 10:37 AM Mike S wrote:

> At 01:00 PM 3/24/2008, Mike Collum wrote...
>> The voltage stabilizers on all three of my '84 models only use the
>> outer
>> pins.  The middle pin is in the air (no female connector).  All three
>> have always been that way and work fine.
>
> The middle pin is internally connected to the tab, which should be
> grounded to the printed circuit foil. Guaranteed, it won't work
> correctly if it doesn't have 3 connections.
>