Daymarc 620 S235 is an industrial control unit used to drive and monitor high‑speed test handlers in semiconductor inspection lines. Common failure points on this class of units include power supply degradation (brownouts, ripple), I/O module wear or solder joint fatigue, and firmware corruption due to over‑temperature cycling. Begin diagnostics by verifying the 24 V/48 V DC rail integrity with a multimeter, inspecting all connectors for corrosion or loose pins, and reviewing any logged error codes via the unit’s diagnostic interface. If power is stable, check the status LEDs and I/O module voltages; if anomalies persist, proceed to firmware checksum verification and replace suspect components as needed.[oss-gpt-20b]