What was found
PILOTS REPORTED HEAVIER THAN NORMAL BRAKING ON TAXI OUT FOR TAKE OFF ROLL. ON TAKE OFF, ANTI SKID FAIL AMBER CAS AND BRAKE MAINT REQD CYAN CAS ILLUMINATED. PILOT FOLLOWED QRH PROCEDURES AND ATTEMPTED TO RESET ANTI SKID SYSTEM. WHEN IT WAS DETERMINED THAT THEY WERE UNABLE TO DO SO, REQUESTED A LONGER RUNWAY IN THE AREA NEAR WHERE WE ORIGINALLY FILED TO LAND. PILOT LANDED WITHOUT FAULT AND USED MAX TR AND RUNWAY LENGTH TO SLOW DOWN SAFELY. ATC DECLARED EMERGENCY. ON LANDING,, EVEN A SLIGHT TOUCH TO BRAKES CAUSED SYSTEM TO LOCK UP ALMOST IMMEDIATELY. PILOT USED A MIXTURE OF HAND BRAKE AND TR FOR CONTROL UNTIL ARRIVING AT THE FBO. IT HAS BEEN DETERMINED THAT A BRAKE CONTROL UNIT IS FAULTY AT THIS POINT.