What was found
DOWNWIND AT 3000 FT WENT TO SLATS EXTEND AND IMMEDIATELY GOT A MASTER WARNING FOR AVIONICS SMOKE, FO STATED HE THOUGHT HE SAW SMOKE. DECLARED EMERGENCY AND LANDED. AFTER LANDING WE COULD NOT SMELL SMOKE OR SEE VISIBLE SIGNS OF SMOKE. AFTER FIRE DEPARTMENT INSPECTED AIRCRAFT WE TAXIED TO GATE. EMERGENCY DECLARED. PERFORMED AVIONICS COMP. ADJ/TEST. COCKPIT AND MAIN BAY WOULD NOT TEST. MIN EQPT TEST GOOD. REMOVED AND REPLACED 11WA, 12WA AND 13WA SMOKE DETECTORS, PERFORMED ADJ/TEST AGAIN WITH NO FURTHER DEFECTS. ALL CHECKS ARE GOOD.