As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING TAXI OUT, WHEN F/A CALL BUTTON WAS SELECTED, BOTH CALL AND EMERGENCY ILLUMINATED ON PANEL, ALL LIGHTS BUT PA ILLUMINATED ON F/A'S PANEL. NO COCKPIT/CABIN COMM OR PA ANNOUNCEMENTS WERE POSSIBLE. FOUND A MELTED LIGHT SOCKET ON AFT OVERWING COCKPIT CALL LIGHT. REPLACED LIGHT SOCKET ASSY IAW CRJ WM 20-00-00. PERFORMED OPS CHECK OF P/A SYSTEM. OPS CHECKS GOOD.