DEC-00-HZTA-D TU55 May69

This document is an Instruction Manual for the Digital Equipment Corporation (DEC) Type TU55 DECtape Transport.

The TU55 is a solid-state, bidirectional magnetic tape drive designed for use in DEC digital computer systems. Its primary function is to provide a fixed-address magnetic-tape facility for high-speed data loading, readout, and program updating.

Key aspects described in the manual include:

• Functionality: It records and plays back information on five channels of 0.75-inch tape using direct-drive reel motors (without capstans or pinch rollers) and Manchester phase recording. Tape motion is bidirectional at approximately 93 inches per second.
• Control: The TU55 can be operated in either a remote (programmed) mode, receiving commands (GO, STOP, FORWARD, REVERSE, ALL HALT) from an external DECtape control system, or a local (manual) mode via front-panel rocker switches. It features solid-state switching circuits and SCR motor drivers for precise tape movement and electromagnetic brakes for stopping.
• Technical Details: It utilizes DEC's FLIP CHIP logic modules and operates on standard DEC +10VDC, -15VDC, and 115VAC power. It has a capacity of approximately 2.7 x 10^6 bits per reel.
• Maintenance Focus: The manual is primarily intended for maintenance personnel. It provides detailed theory of operation, guides for controls and indicators, and comprehensive sections on:
  • Preventive Maintenance: Weekly and monthly schedules for cleaning, lubrication, and diagnostic checks.
  • Adjustments: Procedures for tape tension and transport stop adjustments.
  • Troubleshooting: Checks for head output, head skew (which is factory-set and not field-adjustable), write enable circuits, and general logic and electromechanical issues.
  • Parts Information: Lists of recommended spare parts and references to engineering drawings.

The document emphasizes the TU55's compatibility with existing DECtape control systems, sometimes requiring a Level Amplifier module for interfacing with older relay-switched transports.