The Heidenhain LS 406 is a sealed linear encoder designed for high‑precision position measurement in NC machine tools and inspection equipment, offering 1 µm or 0.5 µm step resolution with an 11 µA peak output signal. Common failure modes for this class of encoders include contact wear on the scale strip, corrosion or contamination inside the sealed housing, and degradation of the electrical contacts in the 9‑pin connector. Typical repair actions involve inspecting the scale surface for scratches or debris, cleaning the contact pads with isopropyl alcohol, and verifying that the output signal amplitude matches manufacturer specifications under load. First‑check diagnostics: confirm power supply voltage to the encoder, verify continuity and correct wiring on the 9‑pin connector, and review any error logs from the host controller for position or signal loss indications.[oss-gpt-20b]