DECpc 433T

This document is a comprehensive service guide for the DECpc 433T computer, published in May 1991 by Digital Equipment Corporation. It is designed for trained service technicians to diagnose and repair the base system, with specific information on installing, replacing, and configuring options covered in separate installation guides.

The guide is organized into sections covering:

• Overview: Introduces the DECpc 433T as a high-performance EISA computer usable as a standalone unit or in a network environment (PCSA). It details the base system components, including the 33MHz i486 processor, expandable RAM (4MB to 64MB), 128KB cache, EISA expansion slots, 383-watt power supply, diskette drive, and various configuration diskettes. It also lists available options such as different monitors, keyboards, graphics adapters, hard drives, CD-ROM drives, math coprocessors, and network interface boards.
• Troubleshooting: Provides a systematic approach to identifying and resolving problems. This includes details on internal ROM-based diagnostics, special tools (like QAPlus/fe software and loopback connectors), the normal power-up sequence, and procedures for scenarios like "No Power," "System Does Not Boot," and issues after the "System Boots." It extensively lists primary and secondary beep codes, as well as BIOS error messages, and offers symptom-based troubleshooting for system unit, disk, and monitor problems.
• FRU (Field Replaceable Unit) Replacement: Offers step-by-step instructions for removing and replacing various components. These procedures cover the keyboard, monitor, mouse, front door, top cover, side door, power supply, diskette drives, optional drives, option boards, control panel, speaker, main logic board, Single-In-Line Memory Modules (SIMMs), external cache memory, real-time clock, EISA configuration RAM, and the Weitek 4167 math coprocessor.
• Technical Appendices: Includes electrical specifications for the DECpc 433T base system and pin assignments for peripheral interfaces such as the parallel port, RS-232 serial ports, keyboard connector, and power supply connectors.

The document emphasizes safety precautions like disconnecting power before servicing and using anti-static measures. It also highlights the use of a System Configuration Diskette for setting up and configuring the computer and its options.