What was found
FLT 4690 - CREW REPORTED THAT HYDRAULIC SYSTEM NR 1 SYNOPTIC PAGE SHOWS ZERO QUANTITY. HYDRAULIC QUANTITY THEN FLUCTUATED BETWEEN 2600-2900 PSI. HYDRAUCLI PUMPS THEN RAN DRY FOR 25 MINUTES WITH NO FLUID. CAPTAIN DECLARED AN EMERGENCY AND RETURNED TO ATL. FLIGHT LANDED SAFELY. MAINTENANCE REPLACED NR 1 EDP PRESSURE LINE. MAINTENANCE CHANGED THE ENGINE PUMP AND ELECTRONIC PUMP FOR PREVENTATIVE MEASURES. OPERATIONAL AND LEAK CHECKS WERE GOOD. AIRCRAFT RETURNED TO SERVICE. (M)