MP00006 LP20 Nov75

This "Field Maintenance Print Set" document from Digital Equipment Corporation (1976) provides comprehensive technical information for the LP20 Line Printer System. It serves as a detailed manual for the maintenance and configuration of the LP20 system and its various models (e.g., LP20-AA, LP20-AB).

The document includes:

• System Overviews: High-level block diagrams of the LP20 Line Printer System and its controller, as well as module utilization breakdowns.

• Detailed Component Documentation: Extensive electrical schematics, parts lists, and printed circuit board (PCB) layouts for critical sub-systems and modules, including:

  • LP20 Translation RAM (including bus address registers and power pins).
  • LP20 Control modules (address selection, UNIBUS control, NPR clock, interrupt, RAM parity, status and error, UBUS drivers, register select, checksum, power pins).
  • LP20 Data Path modules (printer multiplexer, RAM address, data multiplexer, page counter, carriage control, LPT interface, UBUS & LPT cable, power pins).
  • LP20 Backplane, wired assemblies, power harnesses, and LP20 cables.

• Configuration and Rework Instructions: Specific notes on jumper and DIPswitch configurations, particularly for module interchangeability (e.g., M8587 being replaced by M8571), and detailed rework instructions for PCB modifications.

• Wiring Information: Detailed wire lists for the system.

Overall, it is a highly technical reference designed for in-depth understanding, troubleshooting, and repair of the LP20 Line Printer System.