What was found
WHILE MAINTENANCE PERSONNEL WERE PERFORMING A ROUTINE POST FLIGHT INSPECTION, A TECHNICIAN DISCOVERED A PROBLEM. ACFT POWERED BY EXTERNAL POWER, AND CABIN ENTERTAINMENT SYS OPERATING (PLAYING A DVD MOVIE) WITH THE AUDIO SYSTEM VOLUME AT A LOW LEVEL. AFTER A FEW MINUTES OF OPERATION, A TECHNICIAN NOTICED SMOKE AND FUMES COMING FROM TWO OF THE FORWARD CABIN SPEAKERS (LOUNGE AREA). ONE SPEAKER EMITTED A FLAME APPROXIMATELY 2 TO 3 INCHES IN LENGTH. THE TECHNICIAN QUICKLY SHUT DOWN ALL AIRCRAFT ELECTRICAL POWER, AND RETURNED TO THE DAMAGED SPEAKER AREA WITH AN ONBOARD FIRE EXTINGUISHER. THE FLAME HAD SELF EXTINGUISHED, HOWEVER, THE CABIN WAS VERY SMOKEY AT THAT POINT. UPON FURTHER EXAMINATION, (2) SPEAKERS HAD