Basic checks during troubleshooting: During which named method or phase should you verify all power supply voltages before deeper fault isolation?

Question

Accepted Answer

Introduction / Context: Power integrity underpins every digital and analog function. Before pursuing complex hypotheses (timing, logic, firmware), best practice is to verify that each required supply rail is present, within tolerance, and free of gross ripple. This question asks at what point in a structured troubleshooting process that verification belongs. Given Data / Assumptions: Multiple rails may exist (e.g., +12 V, +5 V, +3.3 V, 1.8 V). Symptoms may be varied or intermittent. You have access to a DMM/oscilloscope for DC and ripple checks. A methodical workflow is followed. Concept / Approach: During diagnosis (the analytical phase following symptom confirmation), technicians collect foundational measurements. Power checks are among the first because out-of-spec rails can mimic many other faults. The half-split method is a signal-path isolation technique used later to divide and conquer. Repair and final test occur after a fault is identified and corrected, respectively. Therefore, verifying supply voltages is part of the diagnostic phase, often step one. Step-by-Step Solution: Measure each rail under load and compare with datasheet/board specs.Check ripple and transient behavior on sensitive rails.If rails are out of spec, fix power issues before proceeding with logic-level analysis.If rails are good, proceed to isolation steps (including half-split if helpful). Verification / Alternative check: Document voltages in a service log and compare with a known-good unit. If anomalies disappear after correcting a power rail, this confirms that diagnosis was the correct phase to perform the check. Why Other Options Are Wrong: half-split: a later-stage isolation technique for signal paths.repair: action taken after diagnosis, not before.final test: confirms restoration; supply verification should be long complete by then. Common Pitfalls: Skipping ripple checks; measuring rails with the load disconnected; ignoring ground integrity or connector resistance that causes under-load droop. Final Answer: diagnosis

Testing and Troubleshooting Questions