Sepro Robotique S 900‑II is a numeric controller and teach‑pendant unit designed for Cartesian robot applications such as unloading injection moulding machines. Common failure modes include CPU board or PCB malfunction (often indicated by persistent error codes or boot failures), power supply degradation leading to intermittent resets, and I/O channel faults that cause loss of axis communication. First‑check diagnostics: verify the 24 V/48 V DC supply voltage and ripple; inspect all connector pins for corrosion or loose contacts; review the system log for specific fault codes (e.g., “CPU error”, “axis timeout”) and confirm the pendant’s display is functioning before proceeding to board replacement.[oss-gpt-20b]