Det‑Tronics 1K/2K/8K Atmospheric Detector is a remote gas transmitter that runs on 24 VDC and outputs a linear 4–20 mA signal proportional to the detected atmospheric concentration; it requires periodic calibration of its catalytic bead sensor. Common failure modes include loss of power or signal due to bad wiring or blown fuses, bead degradation leading to drift or zero‑current output, and internal electronics faults such as a failed op‑amp or regulator. First‑check diagnostics: verify 24 VDC supply at the unit’s input terminals; inspect all wiring and connectors for corrosion or breakage; measure the transmitter’s 4–20 mA output against expected values using a calibrated loop calibrator, and review any error codes displayed on an attached controller or log.[oss-gpt-20b]