What was found
(CAN) DURING FLT, CREW SMELLED ELECTRICAL BURNING ODOR. SYS SYSTEMATICALLY SHUT DOWN INCLUDING, AVIONICS & AIRCRAFT MASTER, ODOR DISSIPATED. ALL RADIOS WERE SWITCHED OFF IN AN ATTEMPT TO SECURE OPERATION OF ONE RADIO FOR COMMS. A/C & AVIONICS MASTER WERE SWITCHED ON WITH AN IMMEDIATE RETURN OF ODOR. A/C AVIONICS MASTER WAS AGAIN ISOLATED & ODOR DISSIPATED. A/C MASTER WAS TURNED ON TO ESTABLISH BASIC A/C SYSTEMS WITH A RETURN OF ODOR. A/C RECOVERED TO MAIN MAINTENANCE BASE WITHOUT FURTHER INCIDENT. UPON INVESTIGATION IT WAS REVEALED THAT POWER TERMINAL OF THE NR 1 AVIONICS RELAY HAD SHORTED TO GROUND. AT THIS TIME THE CAUSE OF THE SHORT IS UNKNOWN.