As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CLIMBING THRU FL220, YELLOW ELEC PWR MONITOR LIGHT FLASHING AND VDC READ 29.6. PERFORMED EMERGENCY CHECKLIST AND WHEN LT GEN SHUT OFF, VDC READ 30.0. RETURNED TO DEPARTURE AIRPORT WITH RT GEN OFF. MAINTENANCE FOUND RT GCU NOT WITHIN ADJUSTED TOLERANCE. ADJUSTED RT GCU. NO DEFECTS NOTED