LGplus Series Text and Graphics Printers

This document is a field service maintenance manual for the Digital Equipment Corporation LGplus Series line matrix printers, including the LG04plus, LG08plus, and LG12plus models. Published in December 1995, it provides detailed procedures and information for servicing these printers, which are designed for high-volume text and graphics printing with a flash memory architecture, variable-speed shuttle, and half-step paper feed.

Key areas covered in the manual include:

1. Maintenance Overview: General information about the printer, essential maintenance notes, safety notices, and a list of required tools and supplies.
2. Scheduled Maintenance: Instructions for routine preventive maintenance, such as inspecting the printer for damage or wear, and cleaning various components like the cabinet, print mechanism, shuttle frame assembly, and card cage fan assembly.
3. Troubleshooting: Guidance on diagnosing and resolving printer malfunctions, using LCD fault messages, addressing symptoms without specific error codes, running diagnostic tests, and generating hex code printouts.
4. Adjustment Procedures: Step-by-step instructions for precise adjustments, including paper feed timing, platen open belt, paper drive motor pulley, paper scale, platen gap, ribbon guide, splined shaft skew, end of forms distance, hammer phasing, and installing software.
5. Replacement Procedures and Illustrated Parts List: Detailed steps for the removal and installation of field-replaceable units (FRUs), such as circuit boards (CMX controller, power supply), fans, motors, paper path, shuttle frame assembly, and various other mechanical and electrical components, complete with illustrated diagrams and part numbers. The manual explicitly states that electronic components and hammer banks are not field-repairable and must be replaced as assemblies.
6. Principles of Operation: Explanations of how line matrix printing works, the mechanisms of the printer (shuttle frame, hammer bank, paper transport, ribbon transport), and the logical control architecture involving the CMX controller board (Data Controller and Engine Controller), power supply, and printer interfaces.

The document stresses the importance of safety, providing warnings related to electrical shock and proper handling of delicate printer parts throughout the maintenance procedures. It also includes appendices with wire data, detailed printer specifications (duty cycle, ribbon, paper, environmental, electrical, interfaces, printing rates), metric conversion tables, torque tables, and a list of abbreviations and signal mnemonics.