What was found
PAX SEAT 27B WHEN AUDIO HEADPHONES PLUGGED IN, PAX REPORTED HEADSET HEATING UP AND SAW SMOKE. TRIED A BRAND NEW PAIR OF EAR BUDS AND THEY BEGAN TO GET HOT. DEFER TO MEL 23-37-01A. PLACARD INSTALLED. PULLED AND SECURED C/B ON P11 AND P70 IAW MEL, M, PROCEDURES. PLACED "DO NOT USE" PLACARD ON IFE PANEL IAW MEL, M, PROCEDURES. ALL MEL M, PROCEDURES COMPLYED WITH. REVERSED, M, PROCEDURE & PERFORMED T/S. VISUALLY CHECKED WIRING & HARNESS FOR ANY DAMAGE. FURTHER T/S FOUND PCU AT FAULT. REPLACED PCU AT 27B REF AMM 23-34. OPS CHECKED OK. MONITORED FOR 15 MINUTES, NO HEATING NOTED. REMOVED MCO & PLACARD. ACFT OK FOR SERVICE.