DECconcentrator 500 Problem Solving

This document is the "Problem Solving" manual for the DECconcentrator™ 500, published in January 1992.

Its primary purpose is to guide users through troubleshooting, testing, and servicing the DECconcentrator 500 unit.

Key contents include:

• Controls and Indicators: Descriptions of the unit's physical controls, connectors, and LED indicators.
• Troubleshooting and Testing: Methods for diagnosing and isolating faults, including a problem-solving checklist, self-test procedures (both power-up and network management initiated), and loopback testing. It provides detailed tables linking LED symptoms to probable causes and corrective actions for various components (main unit, Network Management Card, Port Cards, optical bypass relay), and instructions for measuring optical power.
• Removal and Replacement Procedures: Step-by-step instructions for preparing the concentrator for servicing and replacing Field Replaceable Units (FRUs) such as option cards, the chassis cover, OBM card, controller/backplane board, fan, power supply, power connector/filter, and circuit breaker, along with reassembly guidelines.
• Appendices: A parts list with FRU part numbers, detailed physical, environmental, and electrical specifications for the concentrator and various cable types (fiber optic, ThinWire, Shielded Twisted-Pair), and a list of related documents for further reference.
• Safety Information: Critical warnings are emphasized throughout, covering power disconnection before servicing, laser light exposure hazards, and electrostatic discharge (ESD) precautions.

The manual is intended for system/network managers and trained Digital Equipment Corporation personnel involved in product maintenance and repair, with a prerequisite knowledge of Fiber Distributed Data Interface (FDDI).