MP01359 RA81 Oct82

This document is a Field Maintenance Print Set for the Digital Equipment Corporation (DEC) RA81 Disk Drive System. It is a comprehensive technical manual providing detailed information necessary for the maintenance and understanding of the system's various components and configurations.

The document includes:

1. Overall System Configuration: Details on the RA81 ship configuration, including unit variations (voltage, frequency, amperage, wattage), general mechanical requirements, slide installation drawings, and internal cabling layouts (e.g., for single, dual, or triple drive cabinets).
2. Assembly and Sub-Assembly Details:
   • Disk Drive Assembly: Comprehensive mechanical assembly drawings, detailed views of various components, and parts lists.
   • HDA (Head/Disk Assembly) R/W Module: Assembly information and parts lists.
   • H7660 Unit Assembly (Power Supply): Assembly views, wiring diagrams (electrical schematics), and detailed parts lists for the power supply, including its connector, regulator, and capacitor boards.
   • Logic Chassis Assembly: Assembly drawings, details of the lower chassis, logic access cover, and associated components, along with parts lists.
   • Microprocessor: Detailed component layouts, wire add instructions, and extensive multi-page electrical schematics illustrating its complex logic (covering interfaces for operator panel, personality module, servo/read/write data paths, and various control signals).
   • Operator Control Panel Assembly: Assembly views, detailed component layouts, and electrical schematics (including specific details for the RA80 operator control panel).
   • Servo Board and Stiffener Assembly: Assembly views and parts lists.
   • Servo Control: Highly detailed multi-page electrical schematics covering the entire servo system, including gain, DC zero, sync detection, peak detection, phase detection, velocity control, motor drivers, DAC & A/D converters, and slave processor/ROM/RAM interfaces.
   • Read/Write Circuitry: Detailed component layouts, wire add instructions, and extensive multi-page electrical schematics illustrating the complex data read/write paths, AGC (Automatic Gain Control), imbed read/write, and burst/AGC control.

Each major section typically includes:

• Drawings: Physical layouts, assembly instructions, and detailed component views.
• Parts Lists: Itemized lists of components with quantities and part numbers.
• Electrical Schematics: Detailed circuit diagrams illustrating functional blocks and interconnections.

The document emphasizes its proprietary and confidential nature, stating that its contents are for information purposes only and subject to change by Digital Equipment Corporation.