The Simplex 565‑488B is a power supply board used in voice‑command evacuation notification panels, typically mounted on fire alarm control cabinets. Common failure points for this class of industrial power supplies include degraded capacitors, burned fuses or blown rectifier diodes, and overheating due to inadequate ventilation or dust buildup. First‑check diagnostics: verify the incoming AC voltage and confirm it matches the board’s rated input; inspect the output rails with a multimeter for proper DC levels and continuity on protection circuits; visually examine the board for bulging capacitors, scorch marks, or loose solder joints before proceeding with component replacement.[oss-gpt-20b]