As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
WITH ENGINE NR 2 RUNNING, SMOKE ENTERED COCKPIT FROM UNKNOWN SOURCE. GOT INTERMITTENT NR 3 MAIN CARGO BAY SMOKE ALARM & LIGHT. ALARM & LIGHT OCCURED 2 TIMES FOR 1 SEC. SHUTDOWN NR 2 ENGINE & POWERED ACFT WITH APU. SMOKE DISPERSED. ON APU & EXT POWER, NR 2 BUSS IS NOT POWERED. ANNUNCIATOR PANEL HAD UNDEREXCITATION LIGHT NR 2 SYSTEM. R & R NR 2 VOLTAGE REGULATOR. SMOKE CAUSED DUE TO LOST POWER TO BUSS TIE BREAKER TO RT PACK. R & R GCU . R & R GENERATOR BREAKER (C814) & BUSS TIE BREAKER. RAN ENGS AND TAXIED A/C NO SMOKE NOTED.