Epson Service Manual: The Definitive Guide for Your Epson LQ-670K (and LQ-670) Dot Matrix Printer

For businesses and operations that demand robust, high-volume, and reliable printing of multi-part forms, invoices, receipts, and continuous paper, the Epson LQ-670K (and its core model, the LQ-670) dot matrix printer is a stalwart choice. These 24-pin dot matrix printers are renowned for their exceptional durability, low running costs, and ability to handle demanding print jobs with continuous paper feeds. While built to last for many years in rigorous environments, even these workhorses can eventually experience mechanical wear, electronic malfunctions, or require routine maintenance to keep them operating at peak efficiency.

Instead of facing the complexities of finding specialized repair services or the cost of replacing a perfectly capable printer, imagine possessing the precise technical knowledge to diagnose, adjust, and resolve problems yourself. This is exactly what the Epson LQ-670K / LQ-670 English Service Manual provides – your ultimate resource for effective repair, critical adjustments, and meticulous long-term maintenance of these essential dot matrix printers.

What is the Epson LQ-670K / LQ-670 Series Service Manual?

The Epson LQ-670K / LQ-670 Service Manual is Epson’s official, highly detailed technical document created specifically for this range of 24-pin dot matrix printers. Far more comprehensive than the user manual, which focuses on daily operations and basic troubleshooting, this service manual is an absolute necessity for trained service technicians and ambitious DIY enthusiasts. It offers an in-depth exploration of the intricate mechanical, electrical, and firmware systems that power these printers, with a particular focus on their impact printing mechanism, continuous paper handling, and robust build. Essentially, it serves as the definitive blueprint, guiding you through every step of understanding, troubleshooting, disassembling, adjusting, repairing, and accurately reassembling your Epson LQ-670K or LQ-670 printer to maintain its optimal performance.

Key Repair Information and Contents You’ll Discover Inside

This comprehensive service manual is a goldmine of technical data, absolutely vital for anyone looking to perform in-depth maintenance or repairs on their Epson LQ-670K / LQ-670 dot matrix printer. You can expect to find:

• Product Description and Specifications: A thorough overview of the printer, outlining its features, detailed technical specifications (e.g., print speed, 24-pin head, character sets, paper handling capabilities for continuous forms, multi-part form support, and standard interfaces like Parallel and USB). It will detail its robust impact print head technology and ribbon cartridge system.
• Operating Principles / Theory of Operation: Detailed explanations of how the printer’s various mechanisms function. This includes:
  • The precise mechanics of the print head (pin firing mechanism, print head movement across the platen).
  • The paper feeding mechanisms (tractor unit for continuous paper, friction feed for single sheets, platen rotation).
  • The ribbon drive system.
  • Sensor operations (paper detection, top-of-form, platen gap adjustment).
• Safety Information: This section is paramount. Working with electrical components, delicate moving parts, and the print head (which can become hot) requires caution. The manual provides explicit warnings and and precautions, emphasizing how to safely disconnect power, handle electronic components, and avoid injury from moving parts. Always prioritize your safety by carefully reading and following these guidelines.
• Disassembly and Assembly Procedures: Step-by-step, clearly illustrated instructions guiding you through the safe and correct method for taking apart and putting back together every section of your printer. This is crucial for accessing internal components such as the print head, platen, paper feed mechanism, or main logic board for cleaning, inspection, or replacement. Dot matrix printers often require specific procedures for detaching the print head and ribbon drive.
• Troubleshooting Guides: Extensive sections dedicated to diagnosing common problems. These are often presented with logical flowcharts and tables, helping you pinpoint the root cause of an issue based on observed symptoms or diagnostic self-tests. This includes:
  • Error Code List / LED Indicators: A comprehensive enumeration of error patterns indicated by the control panel lights, detailing their meaning and recommended steps for resolution.
  • Print Quality Issues: In-depth guidance on troubleshooting and resolving common print defects such as faded print, missing dots, smudging, or inconsistent character formation. Solutions often involve replacing the ribbon, cleaning the print head, or adjusting the platen gap.
  • Paper Handling Problems: Solutions for various paper jams, misfeeds, or issues with continuous paper not feeding correctly through the tractor or single sheets not loading properly.
  • Electronic Faults: Guidance on diagnosing issues related to the main board, power supply, or interface connections.
• Adjustment Procedures: Provides precise instructions for calibrating various parts of the printer after repairs or component replacements to ensure optimal print quality and consistent paper feeding. This includes:
  • Print Head Gap Adjustment: Crucial for optimizing print quality based on paper thickness, especially for multi-part forms.
  • Top-of-Form (TOF) Adjustment: Essential for accurate paper alignment at the start of printing.
  • Tear-Off Position Adjustment: For precise tearing of continuous forms.
  • Micro Adjustments: Fine-tuning paper feed and other parameters.
• Maintenance Procedures: Guidelines for comprehensive preventive maintenance, including routine cleaning instructions for the print head, platen, paper path, and internal components. It will also cover the proper procedure for replacing the ribbon cartridge.
• Circuit Diagrams and Wiring Diagrams: For those with electronics expertise, these detailed diagrams provide a visual representation of the printer’s electrical systems, component layouts on printed circuit boards (PCBs), and precise wiring connections, enabling advanced electrical diagnostics.
• Exploded Diagrams and Parts List: Visual breakdowns of the printer’s various assemblies, showing every component in an exploded view with its corresponding part number. This is incredibly useful for identifying and ordering the correct replacement parts from suppliers like diyinkjet.com.

Why This Epson Service Manual is an Indispensable Repair Resource

For dedicated owners, IT support staff, and DIY enthusiasts working with the Epson LQ-670K / LQ-670 dot matrix printer, this service manual offers profound benefits:

• Significant Cost Savings: Empower yourself to perform many common maintenance tasks, critical calibrations, and repairs in-house, drastically reducing expenses on external technician visits. This is particularly valuable for these highly durable, but often older, dot matrix printers.
• Minimized Downtime: Quickly identify and resolve issues, getting your essential printer back into operation faster and minimizing disruption to business operations.
• Extended Printer Lifespan: Proactive maintenance and accurate repairs, guided by official procedures, help maximize the operational life of your durable dot matrix investment.
• Empowerment Through Knowledge: Gain a deep and practical understanding of your printer’s robust mechanisms, leading to greater confidence in tackling future problems independently.