What was found
ACRID BURNING SMELL IN VICINITY OF ROW 10 & 11, UNABLE TO IDENTIFY SOURCE. ONLY OCCURRED ON GND DURING BOARDING. BOTH BALLAST ROW 10 RT SIDE DISCONNECTED. RAN APU WITH BOTH PACKS ON FOR 10 MINUTES & ALL CABIN LIGHTS ON, NO MORE BURNING SMELL. RT SIDE CTR AISLE & SIDEWALL LIGHT BALLASTS DISCONNECTED, ROW 10 & 11 FLUORESCENT LIGHTS INOPERATIVE, PLACARDED & PLACED ON MEL. MC IAW LP 267086 3 ACRID SMELL FROM ROWS 10 & 11 ON GND, DETERMINED 1 OF THESE 2 BALLASTS BAD.