Fuji Electric AD‑15B‑P‑SE is an industrial analog‑to‑digital converter module used to digitize process signals (e.g., 4–20 mA or ±10 V) for control systems. Common failure modes in this class include power supply degradation, input bias drift, and internal ESD damage from cable handling; the device may also exhibit intermittent conversion errors due to solder joint fatigue or component aging. First‑check steps: verify that the module receives its rated supply voltage and current (typically 12 V DC ±10 %); inspect all input/output connections for corrosion or loose contacts; and review any diagnostic LEDs or error codes reported by the host controller. If power and cabling are correct, perform a scope probe of the ADC output to confirm proper digital data rates before proceeding with deeper board inspection.[oss-gpt-20b]