C172RG PLT EXPERIENCED ELECTRICAL PROBS INFLT. FINDING PLTS OPERATING HANDBOOK INADEQUATE; USED LOGICAL TROUBLESHOOTING TO RESTORE SYS LOST AND CONTINUED ON.

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A C172RG RENTAL ACFT. FLT WAS ROUND-TRIP TO EL PASO DIRECT. ABOUT 30 MI W OF INK VOR COMPLETE RADIO SYS LOST. ALL ELECTRICAL FUSES APPEARED GOOD. FUEL GAUGES WENT FROM READING ALMOST FULL TO ABOUT EMPTY. TURNING COM MASTER SWITCH OFF RETURNED FUEL GAUGES TO PROPER READING. WITHOUT RADIOS; LNDG ELP WAS A NO-GO; DID 180 DEGS TO RETURN TO MDD. FEARED THAT USED COIL INSTALLED BY FBO HAD SOMEHOW FAILED. TROUBLESHOOTING INFLT NEXT 30 MINS FAILED TO RESOLVE. FINALLY I PULLED THE ALTERNATOR FUSE SWITCH OUT; WAITED 2-3 SECONDS AND PUSHED BACK IN AND COM RETURNED. RESUMED FLT TO ELP WITHOUT FURTHER INCIDENT. BELIEVE AN OVER-VOLTAGE CONDITION CAUSED THE ALTERNATOR CTL UNIT TO AUTOMATICALLY REMOVE ALTERNATOR FIELD CURRENT THUS SHUTTING DOWN ALTERNATOR. CESSNA INFO MANUAL FOR THE CUTLASS RG MODEL 172RG DOES NOT PROVIDE EMER PROCS FOR THIS INCIDENT THAT WORKS. MANUAL SUGGESTS (PAGE 7-32) TURNING MASTER SWITCH OFF AND ON. COM MASTER SWITCH DIDN'T WORK. PULLING THE ALTERNATOR FUSE SWITCH OUT AND PUSHING IT BACK IN DID. MY CLUE WAS PAGE 3-10 EMER PROCS FOR ELECTRICAL PWR SUPPLY SYS 'AMMETER INDICATOR DISCHARGE' WHICH IT DID. STEP #2 SAYS TO CHK THAT ALTERNATOR CIRCUIT BREAKER WAS IN; WHICH IT WAS. I NEVER CYCLED THE ENG MASTER SWITCH SO DON'T KNOW IF THAT WOULD HAVE FIXED IT; MOST PLTS ARE ADVERSE TO TURNING ANYTHING OFF THAT HAS TO DO WITH A SINGLE-ENG PLANE UNLESS IT'S ON FIRE. SINCE THE FUSE WAS IN AND UNLIKE THE OTHER 'POP-PUSH TO RESET TYPE' AS IT HAD A TIT LIKE IT WAS MEANT TO PULL I FIGURED 'WHAT THE HELL' AND PULLED IT. NOTHING HAPPENED SO I PUSHED IT BACK IN AND RADIOS; VOR; XPONDER ALL CAME TO LIFE.