As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
SHORTLY AFTER TAKEOFF, THE FLIGHT CREW REPORTED A PROBLEM WITH THE NR 1 ALTERNATOR. THEY WERE ALERTED BY AC VOLT FAIL MESSAGE ON THE EICAS SCREEN. AIRCRAFT RETURNED TO DEN, LANDED WITHOUT FURTHER INCIDENT. DENVER MAINTENANCE REPLACED THE NR 1 DAU IAW AMM 31-42-00, OPERATIONAL CHECK WAS CONDUCTED WITH SATISFACTORY RESULTS.