A B757-200 FLT CREW EXPERIENCED FALSE WINDSHEAR WARNINGS ON TAKEOFF; FOLLOWED BY MULTIPLE EICAS WARNINGS AND SYSTEM ANOMALIES. THEY DECLARED AN EMERGENCY AND RETURNED TO THEIR DEPT ARPT.

Narrative

DURING TKOF; AFTER GEAR RETRACTION; WINDSHEAR INDICATIONS AND COCKPIT AURALS (CAPT ADI ONLY SHOWING INDICATIONS). WE BOTH PUSHED THE PWR UP BUT SOON REALIZED THAT IT WAS AN INDICATION PROB ONLY. CAPT AIRSPD WENT TO 0. I DECIDED TO TURN THE ACFT TO FO; AS HIS SIDE WAS WORKING FINE. MY AIRSPD INDICATOR THEN WENT TO NORMAL; AND THEN AIRSPD INDICATOR STARTED SPINNING. STANDBY AND FO INDICATIONS NORMAL. SOON AFTER THAT OVERSPD EICAS AND ASSOCIATED LIGHT ON. VERY SOON AFTER THAT WE HAD THE FOLLOWING INDICATIONS: 1) MACH SPD TRIM EICAS AND ASSOCIATED LIGHT ON. 2) RUDDER RATIO EICAS AND ASSOCIATED LIGHT ON. 3) L AND R EEC EICAS AND ASSOCIATED LIGHTS ON. 4) OVERSPD EICAS AND ASSOCIATED LIGHT ON. 5) PRESSURIZATION CLBING RAPIDLY AT SAME RATE AS VSI. 6) AUTOTHROTTLES. 7) AUTOPLT. WE DECIDED TO GO BACK TO ZZZZ ARPT AS WE WERE AT 2000 FT CLBING TO 3000 FT. WE CALLED DEP AND TOLD THEM THAT WE WERE TURNING BACK TO THE ARPT. WE REQUESTED THE WX AND I LOADED THE APCH AS FO WAS FLYING THE AIRPLANE. HE TOLD ME THAT WE DID NOT HAVE AN AUTOPLT OR FLT DIRECTORS OR AUTOTHROTTLES. HE WAS FLYING RAW DATA UNDER VISUAL CONDITIONS AS I DECLARED AN EMER. WE WERE CLRED FOR AN APCH AND LNDG TO RWY X BUT FO REQUESTED THAT HE WANTED RWY Y AS WE WERE ALREADY AT A 45 DEG ANGLE FROM RWY X AT 3000 FT AND WINDS AND TFC FAVORED THIS RWY. WE WERE THEN CLRED FOR A VISUAL APCH AND LNDG TO RWY Y TO AN UNEVENTFUL AND STABILIZED APCH AND LNDG TO SUCH RWY. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: REPORTER INDICATED EXCESSIVE MOISTURE WAS FOUND IN THE E&E COMPARTMENT; CAUSING THE MULTIPLE ELECTRICAL ANOMALIES.