The Willett 2200 Micro‑Processor Unit is an industrial controller board commonly mounted on pump and process control systems, providing logic processing for I/O and drive functions. Known failure modes for this class of boards include power supply degradation (brown‑out or over‑voltage), capacitor leakage or failure, and microprocessor core faults such as corrupted firmware or stuck reset lines. Initial diagnostics should verify the 24 V/48 V DC input voltage and ripple levels, inspect all surface‑mount capacitors for bulging or leakage, and check for obvious burn marks or loose solder joints on the processor package. A quick code read from any diagnostic port (if available) can confirm whether the microcontroller is booting or stuck in an error state.[oss-gpt-20b]