What was found
WHEN GEAR HANDLE WAS SELECTED DOWN DURING APPROACH, THE GEAR DIDN'T EXTEND, THE RED UNSAFE LIGHT CAME ON, AND THE GREEN GEAR DOWN LIGHTS STAYED OFF. CREW FOUND THE 2 AMP CONTROL CB POPPED. GEAR HANDLE WAS PUT BACK UP, THE CB WAS RESET, AND THE CB POPPED AGAIN, WITH THE SAME INDICATION. GEAR WAS THEN PUMPED DOWN BY HAND, WITH THREE GREEN GEARDOWN LIGHTS. MAINTENANCE TROUBLESHOT AND REPLACED PC BOARD A316, GEAR WAS CYCLED MULTIPLE TIMES WITH NO FURTHER PROBLEMS. THERE WAS ONE PREVIOUS INCIDENT OF THE SAME FAILURE ON WITH THE SAME PC BOARD.