What was found
DURING CRUISE AT FL 330, AT APPROX 2015Z, THE NR 1 NAV FAILED. SHORTLY AFTER THAT, THE CAPTAINS ADI TUMBLED THEN THE TRANSMITT FUNCTION OF THE RADIOS FAILED. REPLIES WERE MADE BY THE IDENT ON THE TRANSPONDER. ALL LIGHTS IN THE COCKPIT OTHER THAN THE MASTER WARNING AND COMPARATOR LIGHT FAILED TO ILLUMINATE. ALSO AS AIRCRAFT DECENDED, THE CIRCUIT BREAKERS FOR THE PRESSURIZATION AND OVERHEAD LIGHT POPPED. REMOVED AND REPLACED BOTH AIRCRAFT BATTERIES PER N2402, NR 1 NAV SYSTEM OPS CHECK GOOD PER MM.