What was found
MDT- FLIGHT 3909 CREW REPORTED EMERGENCY LIGHTS ILLUMINATED DURING TAKE-OFF ROLL FOR APROXIMATELY 5 SECONDS THEN EXTINGUISHED. MAINTENANCE REPLACED EMERGENCY LIGHT CONTROL BOX. OPERATIONAL CHECK GOOD. AIRCRAFT RETURNED TO SERVICE. PROBLEM REOCCURED ON FLIGHT 3889/LGA BUT LIGHTS DID NOT EXTINGUISH UNTIL NR 2 ENGINE WAS SHUT DOWN. ISSUED MEL FOR NR 2 TRANSFORMER RECTIFIER UNIT (TRU) OPERATIONAL CHECK NORMAL. AIRCRAFT RETURNED TO SERVICE.