The Cutler‑Hammer IQA 6400 is a three‑phase power and jitter analyzer that records trend data in non‑volatile memory and interfaces with Cutler‑Hammer software. Common failure points on this class of equipment include degraded power supply modules, failing analog front‑end circuitry (e.g., shunt or transformer cores), and corrupted firmware or communication firmware causing display or log retrieval errors. First‑check steps: verify the 100–600 VAC input is within spec and that all internal fuses are intact; inspect the main PCB for burn marks or loose solder joints, especially around the voltage sensing network; review any error codes displayed on the front panel or in the software logs for indications of firmware corruption or communication faults.[oss-gpt-20b]