What was found
CABIN CREW REPORTS ELECTRICAL/CIRCUITY SMELL IN THE AFT CABIN AT THE LAST FIVE ROWS. GPU ATTACHED. APU ON. PACKS ON. RECRIC FANS ON. NO LOW PRESS AIR ATTACHED. NO FUELER ACTIVITY PRESENT./ PERFORMED TROUBLESHOOTING IAW CRJ700 FIM 21-22-00-810-806. FOUND TOP SIDEWALL BALLAST ABOVE SEAT 19AC TO BE SOURCE OF THE SMELL. REMOVED AND REPLACED SIDEWALL LIGHT BALLAST ROW 19AC IAW CRJ700 AMM 33-21-09-000/400-801-A01. OPS CHECK GOOD.