What was found
FLT 4121 - DURING CLIMB-OUT FROM ATL-CSG, AT APPROXIMATELY 3,000 FT, THE CREW SMELLED SMOKE WITH NO VISIBLE SIGNS. AN EMERGENCY WAS DECLARED AND THE AIRCRAFT RETURNED TO ATL, LANDING SAFELY. MX REMOVED, INSPECTED AND RE-INSTALLED THE SMOKE DETECTOR IN THE ELECTRONICS RACK, INCLUDING INSPECTION OF THE DUCTS AND RELAY SHELVES WITH NO DEFECTS NOTED. MAINTENANCE ALSO PERFORMED TWO THIRTY MINUTE ENGINE RUNS WITH NO ELECTRICAL SMOKE MESSAGES OCCURRING ON THE CREW ALERT PANEL. OPERAITONAL CHECKS GOOD. AIRCRAFT OK FOR SERVICE. (M)