(1) Understand the sequence of events leading to the fault, including the working conditions before the fault and the symptoms afterward.
(2) Carefully analyze the cause or scope of the fault to identify its cause or analyze its extent.
(3) Conduct a visual inspection, primarily checking for loose fixing screws and wiring screws on fuses, relays, contactors, and limit switches. Inspect for broken wires, burnt coils, welded contacts, and the flexibility of moving parts. Address any obvious faults promptly.
(4) Perform a power-off inspection to locate hidden faults. Use a multimeter in resistance mode to check for open circuits, short circuits, or grounding in the fault area's components and circuits. Sometimes a megohmmeter and other devices can be used. If the power-off inspection fails to find the cause, a power-on inspection can be performed.
(5) A power-on inspection is primarily for locating faults that are difficult to detect. Power-on inspections should be conducted without load to prevent accidents.