Illustrated Elna PRO 704 DEX Overlock Sewing Machine - Precision Maintenance & Troubleshooting

Elna PRO 704DEX Instruction Manual - 1995 Edition

This original operator’s manual provides the foundational technical framework required to operate the Elna PRO 704DEX, a high-performance 4-thread overlock machine with integrated coverlock capabilities. Utilizing the machine-specific ELx705 needle system ensures optimal penetration force and stitch security, which is vital for maintaining timing synchronization and preventing needle deflection during high-speed operation. Implementation of these factory-specified settings directly correlates to extended looper longevity and reduced mechanical vibration.

Machine Architecture & Technical Applicability

• Model Series: PRO 704 DEX (Household Overlock Sewing Machine)
• Configuration: 2/3/4 Thread Versatility
• Technical Generations: Electronic Series featuring automatic tension calibration and integrated program display.
• Production Context: Manufactured in Japan (Part No. 11000 / 396160-94).

Operational Efficiency & System Safety

• Safety Synchronization: Triple-interlock safety systems prevent motor engagement if the front door is open, the side door is open, or the presser foot is in the raised position.
• Automated Precision: Integrated tension release levers allow for the immediate extraction of thread chains without risking damage to the needle plate tongue or stitch finger.
• Parts Integrity: Specific component identification for foot control types 4C-335B and 4C-316B ensures electrical compatibility and precise motor speed modulation.

Document Metadata

• Print Number: 11000 (396160-94)
• Language: English, French, German (Trilingual Edition)
• Manufacturer: Elna
• Machine Category: Electronic Overlocker

Factory Calibration & Tension Benchmarks

• Automatic Tension Logic: The system automatically calibrates thread tensions for 14 standard sewing programs based on the selected mode.
• Needle System: Exclusively utilizes ELx705 needles; standard 130/705H (15x1) needles require manual tension compensation to achieve equivalent stitch geometry.
• Light Source Requirements: Replacement bulbs must adhere to a 15-watt rating (15V/5W or 230V depending on region) to prevent thermal damage to the lamp housing.

Visual Navigation & Sectional Schematics

• Threading Topography: Color-coded threading routes (Blue, Red, Yellow, Green) for 4-thread, 3-thread, and 2-thread configurations.
• Interface Mapping: Detailed front and side door area schematics identifying the needle clamp safety lever, moving blade release, and instant rolled hem device.
• Component View: Sectional breakdowns of looper areas including the upper looper, lower looper, and chainstitch looper.

Table of Contents

• Safety Protocols: Household appliance safety and polarized plug instructions.
• Mechanical Overview: Front view, side door area, and front door area components.
• Basic Configuration: Antenna fitting, spool placement, and needle setting.
• Threading Procedures: Routes for overlock, chainstitch, and cover hem.
• Operational Controls: Program selection, stitch length, and differential feed.
• Standard Programs: 14 predefined stitch configurations and display screen logic.
• Technical Adjustments: Cutting width, foot pressure, and looper release.
• Maintenance & Troubleshooting: Oiling, blade replacement, and minor disorder resolution.

Operational Limits & Specifications

• Stitch Dimensions: Stitch length range of 0.5mm to 4.0mm; maximum overcast width of 6.0mm; maximum chainstitch-to-edge width of 9.0mm.
• Differential Feed Ratios: Adjustable from 0.5 (for sheer/light fabrics) to 2.0 (for knits/stretch materials).
• Pressure Settings: Six-stage foot pressure adjustment with a factory-standard setting of "5".
• Cutting Clearance: The moving blade edge must be positioned 0.5mm to 1.0mm below the surface of the fixed blade during replacement.