During the start-up of the circuit shown in figure "B" of the illustration, it is noted that the ends of component "4" remain lighted but the tube does not illuminate. What is likely the cause of this problem? EL-0081

Correct Answer: Option B — component "5" contacts are stuck closed

In fluorescent and discharge lighting circuits, component 5 typically represents the starter contacts. If these contacts are stuck closed, preheat current continuously flows through the cathode filaments keeping the ends lighted, but prevents the high-voltage inductive kick needed to ignite the arc tube.