The MIRTONE 79043 is a two‑zone fire‑alarm supervisory board used in commercial fire‑alarm systems to monitor zone status and trigger alarms or notifications. Common failure modes include capacitor degradation on the power supply section, burned or corroded relay contacts, and firmware corruption that can cause the card to hang or report false fault codes. Initial diagnostics should verify the 24 V DC input voltage and check for any visible burn marks or loose solder joints; test each relay coil with a multimeter and inspect the status LEDs for proper sequencing. Finally, review the system’s event log for recurring error codes that may point to a specific sensor or communication fault.[oss-gpt-20b]