RC25 Disk Subsystem Pocket Service Guide

This document is the Pocket Service Guide (EK-0RC25-PS-002) for the RC25 Disk Subsystem, prepared by Digital Equipment Corporation. It provides comprehensive information for maintaining the RC25 Disk Subsystem in the field.

The guide covers:

• Introduction: A general overview of the RC25 disk drive, a self-contained, random-access, 52 million-byte mass storage device with one fixed and one removable platter. It highlights its availability in tabletop and rackmount versions, master/slave configurations, and extensive internal diagnostics designed for reduced mean time to repair, with no on-site adjustments or special tools required.
• Controls, Indicators, and Jumpers: Detailed explanations of the operator panel controls (Voltage Selection, Power On/Off, Run, Eject, Write Protect, Fault indicators), how to set the Unit Select Number using DIP switches, and the configuration of switches/jumpers on UNIBUS (RUC25) and Q-Bus (RQC25) adapter modules. It also includes procedures for loading/unloading cartridges and manually ejecting a cartridge in case of failure.
• Troubleshooting: Procedures for fault isolation using drive-resident diagnostics, exercisers, and error indications. This includes basic checks, interpreting maintenance indicators (Power OK, Controller Fail, Fault), understanding fatal error codes deposited in the SA register, and utilizing resident exerciser modes (quick-verify, continuous) and host-level diagnostic tests.
• Removal and Replacement: Step-by-step procedures for removing and replacing mechanical and electrical Field Replaceable Units (FRUs) such as covers, power supply modules, operator panels, make-up filters, controller modules, drive modules, drive mechanics assemblies, and cooling fans. It specifies that the head/disk assembly is environmentally sealed and not to be disassembled.

The guide emphasizes that maintenance focuses on diagnostic interpretation and replacement of faulty FRUs, without requiring special tools or adjustments. It includes a list of available documentation and various diagrams to aid in servicing.