Sensor Instrumentation Troubleshooting — real-world interview & field troubleshooting questions with clear, practical answers. Tap any question to open its answer. Showing the first 70 questions free. The complete 150-question set is available as a PDF below. Proximity & Photoelectric Sensors Q1 A proximity sensor does not detect a metal part even though the part is within the expected range. What would you check? Answer Check sensor supply voltage, sensing distance, mounting alignment, target size and sensor face condition. Remove chips or dirt, restore the correct gap, and verify the output changes when the target enters the sensing zone. Q2 A photoelectric sensor detects the product sometimes and misses it at other times. How would you troubleshoot it? Answer Inspect the lens, reflector, alignment, ambient light and product position. Check the sensing mode and sensitivity setting, clean the optics, realign the beam and confirm a stable output while several product...