What was found
ACFT POWERED UP FOR DAILY INSPECT IN HANGER. CABIN INDIRECT LIGHTING TURNED ON, SOON AFTER, SMOKE NOTED COMING FROM AFT HEADLINER ASSY, OUT OF CABIN DOOR. HEADLINER REMOVED & CONNECTER W2J4 WAS BURNED, & WIRING DAMAGED. IT SHOULD BE NOTED THAT WIRING IN CLOSE PROXIMITY TO OXYGEN LINES. SYS DISABLED UNTIL FURTHER INVESTIGATION COMPLETED. FOLLOWING DAY AFT PORTION OF LIGHTING DISCONNECTED & DEFERRED FOR PARTS AVAILABILITY, FRONT PORTION REMAINS OPERATIONAL. CONSULTED WITH RAYTHEON WHO ADVISED THAT SYS HAD 3000 VOLTS, & THAT CONNECTOR DAMAGE COMMON WHEN CONNECTERS ARE MISHANDLED DURING ASSY.