What was found
FIRST FLIGHT OF THE DAY, STARTED THE HELICOPTER AND ALL AS NORMAL UNTIL TURNED ON THE AVIONICS MASTER. ABOUT 45 SECONDS AFTER THAT, RT AFTER TURNING ON THE TCAS AND GETTING A "FAILED" MESSAGE, STARTED TO SMELL SMOKE. THE PASSENGER IN THE FRONT SEAT CONFIRMED THE SMOKE AND POINTED OUT WERE IT WAS COMING FROM - THE TCAS ENCLOSURE.