electrical problem
 

Guys,
Have you ever run into a situation where the charge light did not come on, but the charging system was not working. Here is my situation.

1) Car cold, running at 2K, voltage at battery is 14.
2) After driving car 15-30 minutes, the voltage drops to about 10 but the dash charge light never comes on. The light appears to work as it is on when the switch is on, but not running.

Any advise on trouble shooting this before I start replaceng the Alt/regulator.
Thanks for the help.