DECsystem 5900 Service Guide

This document is the DECsystem 5900 Service Guide, designed for Digital services personnel and self-maintenance customers. Its primary purpose is to provide comprehensive information for diagnosing and correcting on-site problems with the DECsystem 5900 ULTRIX RISC system.

The guide covers:

• Hardware Overview: Details the DECsystem 5900's physical components, including the CPU drawer, mass storage drawers, power controller, system logic (ASICs, CPU daughter cards like R3000A/R4400), memory modules (SIMMs, NVRAM), and TURBOchannel configuration.
• Troubleshooting and Diagnostics: Explains power-up self-tests, various console commands for configuration and testing (cnfg, erl, test, passwd, setenv, etc.), interpreting console error messages, CPU daughter card diagnostic LEDs, and NVRAM diagnosis.
• System Software Management: Describes procedures for powering up and shutting down the system, booting ULTRIX software (from disk/tape or network), and managing console password security and environment variables.
• Major FRU (Field-Replaceable Unit) Replacement: Provides detailed procedures for removing and replacing key components such as power supplies, CPU drawer modules, and mass storage devices. It also includes a list of all field-replaceable units with their part numbers.