What was found
AFTER TAKEOFF CREW WENT TO SELECT GEAR UP & NOTICED THAT THE GEAR DOWNLOCK LIGHTS WERE INOPERATIVE. CREW CYCLED GEAR WITH NO AFFECT AND NOTED THE GEAR UNLOCK LIGHT ILLUMINATED AND EXTINGUISHED AS THOUGH A NORMAL CYCLE HAD BEEN COMPLETED. GEAR ALSO FELT NORMAL DURING THE RETRACT/EXTEND CYCLE. CREW PERFORMED A LIGHT TEST AND LIGHTS STILL WOULD NOT ILLUMINATE. AFTER A FLY BY CONFIRMING GEAR APPEARED TO BE FULLY DOWN, AND A REVIEW OF THE GEAR SCHEMATIC DIAGRAMS, IT WAS DETERMINED THAT ONLY AN INDICATION FAULT WAS OCCURRING AND A SAFE LANDING COULD BE MADE. THE EMERGENCY GEAR SYSTEM WAS ACTUATED AND A SAFE LANDING WAS MADE AT DEPARTURE AIRPORT. TROUBLESHOOTING REVEALED A FAULT IN THE LIGHT DIMMING CIRCUITRY (COMMON TO ALL THREE LIGHTS) AND A FAULTY SOLDER JOINT WAS FOUND AND REPAIRED ON THE CONTROL PRINTED CIRCUIT BOARD (PCB101). EMERGENCY SYSTEM WAS RESET AND SEVERAL NORMAL GEAR CYCLES MADE. AIRCRAFT WAS RETURNED TO SERVICE.