What was found
UPON SWITCHING COMMUNICATION FROM 1 RADIO TO ANOTHER, ALL AVIONICS WENT DEAD AND ALL AVIONICS CIRCUIT BREAKERS POPPED OUT. RECYCLING THE SAME WAS INEFFECTIVE. SUBSEQUENT INSPECTION FOUND THAT AK-550-6 REGULATED DC TO DC POWER BOOSTER CONVERTER USED TO SUPPLY 28VDC TO THE GNS-430W HAD FAILED IN SUCH A MANNER THAT IT CREATED A OVER VOLTAGE POWER LOOP BACK TO THE 14VDC AVIONICS BUS CAUSING ALL 14VDC EQUIPMENT TO SHORT OUT INTERNALLY. THE EQUIPMENT CONSISTS OF A KX-155, AK-950 COOLING FAN, GNA-340 AUDIO PANEL, AND GARMIN GTX-320 TRANSPONDER. ALL OF THIS EQUIPMENT HAS BEEN BENCH TESTED AND FOUND TO BE IRREPARABLE. THE AK-550-6 HAD MULTIPLE INTERNAL FAILURES AS IT HAS INTERNAL OVERLOAD PROTECTION AND SHORT CIRCUIT PROTECTION CIRCUITS THAT ALSO FAILED.