As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING CRUISE ALL ITEMS ON RT ELEC BUSS FLUCTUATED OFF & ON. EICAS ELEC PAGE SHOWED RT IDG VOLT & FREQUENCY FLUCTUATED RAPIDLY FROM 0 TO 110V. EICAS IDG OVERHEAT MESSAGE THEN CAME ON SCREEN. RT IDG SWITCHED OFF. EMERGENCY DECLARED AND DIVERTED. R & R NR 2 IDG IAW AMM 24-11-01. PERFORMED ENG RUN. OPERATIONAL CHECKED NORMAL.