What was found
AFT LAV EMERGENCY EXIT LIGHT AND OVERHEAD LIGHT AS WELL AS THE AFT BULKHEAD EMERGENCY EXIT LIGHTS DO NO ILLUMINATE AS REQUIRED. GAINED ACCESS TO NR 3 AND 4 EMERGENCY LIGHT POWER SUPPLY. REMOVED BOTH POWER SUPPLYS AND INSTALLED 2 TRUE BLUE POWER EMERGENCY LIGHT POWER SUPPLYS. REINSTALLED ACCESS PANELS, CHARGED BATTERYS FOR 1 HOUR. PERFORMED OPERATIONAL CHECK AND ALL EMERGENCY LIGHTS WORK NORMALLY. AIRCRAFT RETURNED TO ORIGINAL CONFIGURATION. NOTIFIED MCC THAT ALL LIGHTS ARE OPS. REQUESTED TO REPLACE NR 1 & 2 EMERGENCY LIGHT BATTERYS SO THAT ALL 4 ARE UPGRADED TO THE TRUE BLUE POWER. IAW AMM 33-50-10.