As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING THE TAKEOFF ROLL, CREW REPORTED THAT THE NR 1 DC GENERATION SYS FAILED PRIOR 80 KNOTS AND THE TAKEOFF WAS ABORTED. TROUBLESHOOTING IDENTIFIED THE NR 1 GENERATOR CONTROL UNIT AS DEFECTIVE. THE DEFECTIVE GCU WAS R & R WITH A REPAIRED UNIT.