What was found
AFTER TAKEOFF LOUD BUZZING SOUND FROM PAX DOOR. VIBRATIONS FELT IN DOOR & GALLEY FLOOR. APPEARED TO GET WORSE AS ACFT WAS PRESSURIZED. LANDING WT 46,500, MAX BTMS 4344. INSPECTED PAX DOOR SEAL IAW AMM 52-11-10. CLEANED PAX DOOR SEAL. DURING INSPECTION FOUND ICE BREAK CABLE BROKEN. R & R IAW AMM 52-11-15. PERFORMED PRESSURIZATION CHECK OF ACFT IAW AMM 21-30-00. NO DEFECTS NOTED. ACFT PRESSURIZATION IS NORMAL.