DECwriter 500i DECcolorwriter 520ic (LJ500 and LJ520)

This service manual provides comprehensive technical, mechanical, and electronic information for the DECwriter 500i (monochrome) and DECcolorwriter 520ic (color) inkjet printers, also known as LJ500 and LJ520. It is intended for product support and fault resolution beyond basic user guide recommendations.

The document describes these "bubble ink jet" printers as offering excellent print quality, fast speeds, low noise, and versatile paper handling, operating at up to 300x300 dpi. It covers the technical characteristics, firmware and character generators, and various optional emulations and fonts.

The manual is structured into nine chapters and an appendix. It includes detailed functional descriptions, block diagrams, and explanations of how the black and color ink-jet print heads operate, including nozzle configurations and resistor actuation. Extensive installation instructions are provided for initial setup, print head installation, memory/font card insertion, and various paper feed options (ASF sheet, manual, sprocket, and second paper tray).

Furthermore, the document outlines user maintenance procedures such as nozzle cleaning and ink reset. It provides thorough diagnostics and tests, including power-on autodiagnostics, print tests for both black and color heads, and a "Data Scope" (hex dump) printout. Troubleshooting guidance is offered for various fault conditions, interpreting LED indicators, and performing mechanical adjustments like print head alignment and belt tension. Finally, it details electrical interconnections of the main board and power supply, and provides step-by-step instructions for the disassembly and reassembly of almost all major printer components for parts replacement.