TU80/81 Operation and Servicing Student Guide

This document serves as a self-paced student guide for Field Service representatives, providing comprehensive knowledge and skills for maintaining and repairing the TU80 or TU81 magnetic tape subsystem. The course covers the physical and functional descriptions of all hardware components, including external components, tape path components (e.g., heads, air bearings), and internal modules like power supply, cooling fans, and logic card cage.

Key topics include:

• Operating Modes and Recording Techniques: Detailed explanations of Phase Encoded (PE) and Group Coded Recording (GCR) methods, as well as streaming and start/stop operating modes, with a focus on how the TU81 automatically selects the optimal mode based on data transfer rate.
• System Architecture: An overview of the TU81 subsystem, including the M8739 UNIBUS adapter module, TMSCP Interface Controller, and the interplay of software and firmware for I/O tasks and control.
• Operational Procedures: Step-by-step instructions for routine operations such as powering up, cleaning the tape path, loading and unloading tape, and performing operator diagnostics.
• Troubleshooting and Diagnostics: Extensive guidance on identifying and resolving problems using power-on health checks, Field Service diagnostic tests, host-based diagnostic tests (EVMBB, EVMBA), and ASCII port diagnostics. This includes interpreting fault codes and utilizing the Pathfinder document.
• Removal and Replacement: Procedures for replacing Field Replaceable Units (FRUs) and verification checks after replacement.
• Installation: Instructions for installing the M8739 UNIBUS adapter module and associated cabling, along with final on-site testing.

The guide consistently highlights differences between the TU81 and TU80 models where applicable, ensuring relevance for both systems.