What was found
AT 4000 FT DC EMERGENCY BUS OFF LIGHT ILLUMINATED WITH ASSOCIATED MASTER WARNING. SHORTLY THEREAFTER THE NR 1 ADDU FAILED. WHEN THIS HAPPENED THE DC EMERGENCY BUS OFF ANNUNCIATOR EXTINGUISHED. PERFORMED ADJUST/TEST DC GENERATION. PERFORMED ADJUSTMENT AND TEST OF EMERGENCY POWER SWITCH IAW AMM 24-23-02-2. DURING TROUBLESHOOTING, NOTICED THE LT WINDSHIELD WIPER CIRCUIT BREAKER HAD A CORNER CRACKED OUT OF IT AND WIRE WAS BROKEN ON A TERMINAL LUG. REPLACED TERMINAL LUG AND LT WINDSHIELD WIPER C/B. OPS CHECKED GOOD. REPLACED EMERGENCY DC BUS FEED C/B. REPLACED MASTER CAUTION LIGHT ASSY. ALL TESTS GOOD.