What was found
AFTER CREW TURNED EXTERNAL GROUND POWER ON, WHITE SMOKE WAS SEEN COMING OUT OF THE DORSAL AIR INTAKE ALONG WITH AN ELECTRICAL BURNING ODOR IN THE AFT EQUIPMENT BAY. POWER WAS IMMEDIATELY TURNED OFF. AFTER TROUBLESHOOTING, MX DISCOVERED THE CABIN 60 HERTZ INVERTER WAS HARD FAILED. REMOVED THE INVERTER AND INCORPORATED SB 60-25-14 WHICH INTRODUCES A NEWER DESIGNED INVERTER. OPS CHECK WAS GOOD AND THE ACFT WAS RETURNED TO SERVICE.