What was found
INSPECTION TYPE:N/A AIR TURNBACK DUE TO SMOKE IN COCKPIT SMELLED SMOKE CLIMBING THROUGH 4000 FT THEN WENT AWAY UNTIL CREW SAW SMOKE AND SMELLED HEAVY ELECTRICAL SMELL AFTER BLOCK IN WITH EXTERNAL POWER CONNECTED. INSPECTED BEHIND PANELS OF F/E PANEL. REMOVED AND REPLACED VOLTAGE REGULATOR, GENERATOR CONTROL PANEL, PERFORMED ADJ TEST PER MM 24-20-00, PERFORMED HIGH POWER RUN. NO SMOKE, NO FAULTS.