What was found
TWICE HAD ELECTRICAL BURNING ODOR FAIRLY STRONG THROUGHOUT CABIN. NO ODOR FOUND, TURNED ALL ELECTRICAL EQUIP ON, ALL LIGHTS THRU RANGES, RAN ON APU POWER AND GRND POWER. ENTERED AND INSPECTED BOTH PIT AND E&E COMPARTMENTS, ALL CABIN AND COCKPIT AREAS. RAN BOTH PACKS. CREW REPORTS 3 HOURS ON GROUND AT LGA, NO PROBLEM, ONLY OCCURRED IN FLIGHT. PERFORMED HIGH POWER RUN AT CRUISE POWER FOR 10 MINUTES WITH ONE PACK AT A TIME OPERATING. ACCOMPLISHED HIGH POWER RUNS ON BOTH ENGINES, ISOLATED PACKS, NO ABNORMAL ODORS NOTED. ALSO NO ABNORMAL ODORS FROM APU SUPPLY.