What was found
FLIGHT 3512. CREW REPORTED RIGHT AFTER APPLYING TAKEOFF POWER RECEIVED NR 1 PACK OVERLOAD FOR ONE SECOND, THEN WENT AWAY. AFTER CLIMBIMG THROUGH APPROX 500FT, DETECTED A FAINT ELECTRICAL BURNING ODOR, RECEIVED NR 1 PACK CLOSED MESSAGE. TURNED OFF NR 1 PACK AND ODOR WENT AWAY. DECLARED AN EMERGENCY AND RETURNED TO DEPARTURE. LANDED WITHOUT INCIDENT. PERFORMED ENGINE RUNS AFTER RECIRCULATION FANS & GASPER FAN INSPECTION, NR 1 ACM AND NR 1 HEAT EXCHANGER REPLACED. STILL RECEIVED AN ELECTRICAL BURN ODOR ON FIRST POWER RUN FOR NR 1 ENGINE WITH NR 1 PACK ON, BLEED NR 1 ON, AND CROSSBLEED VALVE AUTO WITH BOTH ENGINE RUNNING. PERFORMED NR 1 HEAT EXCHANGER OPS CHECKED & LEAK CHECKED GOOD IAW AMM 21-51-02. PERFORMED NR 1 ACM OPS & LEAK CHECKED FOUND GOOD IAW AMM 21-51-00. R & R LT ENGINE CARBON SEAL IAW MM 72-25-25. R & R RT ENGINE CARBON SEAL IAW MM 72-25-25. PASSED FUNCTIONAL CHECK FLIGHT. FLEW AT 3000-10000 FT, NO SMOKE NOTED. AIRCRAFT RETURNED TO SERVICE.