The Power Systems Inc. 9143 is a compact intrinsically‑safe (Ex I) power supply designed to deliver stable, adjustable DC outputs to field devices such as transmitters, solenoid valves, and light barriers. Common failure points for this class include insulation breakdown on the output isolation transformer, degradation of the internal voltage regulator under high ambient temperatures, and over‑current protection tripping when the load exceeds 150 mA. First‑check diagnostics should verify that the input AC supply is within spec (24 VAC ±10 %) and that the output voltage matches the setpoint; inspect for visible arcing or discoloration on the isolation transformer windings; and review any fault codes or status LEDs on the unit’s front panel.[oss-gpt-20b]