Diodes

["Gary Walker" <NashFlash@xxxxxxxxxx>]

   The isolation diode is the big red one on the outside of the alternator
case.   This may be the only one that is damaged.  You can change it with
the alternator in place.  Inspect it by checking continuity in both
directions.  Current should flow in one direction only.  If it is found to
be good, and the output is still not over 14 volts, then clean the armature
where the brushes rub,  Check the brushes for length and free movement, and
if that fails then pull the smaller diodes on the inside and check them for
current flow in one direction.  At this point, go ahead and replace the
bearings with new sealed bearings from a local bearing house.  They are very
inexpensive.  Some parts houses may still have the diodes.
         Your AMC friend,
          Gary Walker
           Owner of some old AMC cars and stuff