The Lock Inspection Systems LTD Metal Chek MK II Type 9 Power Supply is a high‑current DC supply used to drive the metal detector’s sensor and processing electronics. Common failure modes for this class of industrial power supplies include failed bridge rectifier diodes, degraded filter capacitors, overheating due to poor ventilation or over‑load, and burnt or tripped protection fuses. First‑check steps: verify input voltage and polarity with a multimeter; inspect the output rail for correct voltage and ripple while monitoring temperature on the regulator ICs; examine all electrolytic caps for bulging or leakage and replace any that exceed 10 % ESR increase. If the supply passes these checks, proceed to test the internal protection circuitry (short‑circuit, over‑current) and confirm proper operation of the control interface signals.[oss-gpt-20b]