RA90/RA92 Disk Drive

This service manual is designed for Digital Customer Services personnel, providing comprehensive information on the maintenance, servicing, and troubleshooting of RA90 and RA92 disk drives. These are high-density, fixed-media drives with non-removable thin-film media and heads, housed within a Head Disk Assembly (HDA). The RA90 offers 1.216 gigabytes of formatted storage, and the RA92 provides 1.506 gigabytes, both utilizing 13 data surfaces and a dedicated servo surface for precise positioning.

The manual outlines a modern maintenance strategy focused on Field Replaceable Units (FRUs), emphasizing the use of a microprocessor-controlled Operator Control Panel (OCP) for diagnostics, which reduces the need for external test equipment. A six-step maintenance process is detailed, involving analysis of VAXsimPLUS, system and drive error logs, FRU correlation, replacement, and verification via drive-resident diagnostics.

Key procedures covered include the installation of RA90/RA92 disk drives in 60-inch cabinets, encompassing unpacking, deskidding, cabling, and crucial site preparation considerations like power, thermal stabilization, and environmental limits. It also details drive acceptance testing, voltage selection, power-up diagnostics, and OCP functionality.

Operating instructions provide in-depth descriptions of the drive's components (Electronic Control Module (ECM), Preamp Control Module (PCM), HDA, blower motor, power supply, OCP), various operating modes (normal, fault display, test), and functions such as programming the drive unit address.

A significant section is dedicated to drive-resident diagnostics and utilities for detecting faults in the ECM, PCM, and HDA. These include power-up, idle loop, and sequenced diagnostic routines, along with tests for hardware functions, error log display, and revision level utilities.

Troubleshooting guidance is extensive, covering problem identification using VAXsimPLUS, host error logs, drive internal error logs, and OCP fault indicators. It categorizes error reporting mechanisms, prioritizes DSA errors, and addresses media-related issues. A detailed list of error codes, along with fault isolation and suggested FRU replacement orders, is provided.

For physical repairs, the manual offers step-by-step removal and replacement procedures for major FRUs, stressing electrostatic discharge (ESD) precautions and power safety. Additionally, it includes instructions for updating drive microcode using a dedicated cartridge and utility. Appendices detail error recovery levels and customer equipment maintenance guidelines.