Electronics 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. Power Supply & Protection Q1 The electronic unit does not power on at all. Answer Check the incoming supply, fuse, switch, connector, and protection device first. Measure voltage at the board input rather than assuming the supply is present. If the input is correct, check for a short on the power rails and inspect the protection diode, fuse resistor, and regulator. Repair the short or replace the failed protection component, then retest with current limiting where practical. Q2 The fuse blows immediately after replacement. Answer Do not keep replacing the fuse. Disconnect the load and check for a shorted bridge rectifier, MOSFET, capacitor, diode, or wiring fault. Measure resistance on the affected rail and isolate section...