Mitsubishi DB-120 Industrial Sewing Machine Manual

The Mitsubishi DB-120 is a high-performance industrial sewing machine designed for heavy-duty applications, featuring automatic lubrication, electronic speed control, programmable stitch patterns, reverse stitching capability, thread tension adjustment, built-in needle positioner, and safety mechanisms. Powered by 220V AC, 50/60Hz. Below are key sections for safety, features, installation, setup, operation, and troubleshooting.

1. Features at a Glance 2. Installation 3. First-Time Setup 4. Specifications 5. Controls and Settings 6. Connecting Accessories 7. Basic Operation 8. Maintenance Features 9. Care & Cleaning 10. Regulatory Information 11. Troubleshooting

Features at a Glance

Key components: Heavy-duty sewing head, Motor controller, Foot pedal, Bobbin winder, Thread stand, Oil reservoir.

FeatureDescription
Automatic lubricationContinuous oil circulation system for smooth operation
Electronic speed controlPrecise speed regulation up to 2500 SPM
Programmable stitch patternsMemory for multiple stitch configurations
Reverse stitchingBuilt-in reverse function for secure seams
Thread tension adjustmentDigital tension control for various materials
Needle positionerAutomatic needle up/down positioning
Safety clutchProtects against thread jams and overload
Oil level indicatorVisual gauge for monitoring oil levels
Foot pedal controlVariable speed foot controller
Emergency stopInstant machine shutdown button

Installation

Unpack and inspect contents. Place on industrial table or stand.

  1. Position machine: Ensure stable mounting on industrial table with proper clearance.
  2. Connect power: Use dedicated 220V outlet with proper grounding.
  3. Install motor: Mount motor assembly and connect drive belt.
  4. Fill oil reservoir: Use recommended industrial sewing machine oil.
  5. Connect accessories: Install thread stand and bobbin winder.

WARNING! Machine is heavy; use proper lifting equipment. Ensure all electrical connections are secure and grounded.

First-Time Setup

Power on machine; perform initial configuration.

  1. Oil system priming: Run machine at low speed for 5 minutes to circulate oil.
  2. Thread path setup: Follow numbered guides for proper threading.
  3. Needle installation: Insert appropriate needle type and secure properly.
  4. Bobbin winding: Load bobbin and set tension for proper winding.
  5. Stitch length adjustment: Set initial stitch length to 2.5mm.
  6. Speed calibration: Test foot pedal response and maximum speed.

CAUTION! Wear safety glasses during setup. Keep hands clear of moving parts.

Specifications

Controls and Settings

Access control panel for machine settings. Front Panel: POWER, SPEED ADJUST, STITCH LENGTH, REVERSE, NEEDLE POSITION.

Control Panel: POWER, Speed display, Stitch counter, Program buttons, Tension adjustment, Emergency stop.

Stitch Settings: Length adjustment, Pattern selection, Reverse stitch length. Speed: Maximum speed limit, Acceleration control. Maintenance: Oil level monitoring, Stitch counter reset. Safety: Emergency stop function, Overload protection.

Connecting Accessories

Thread stand: Mount behind machine. Bobbin winder: Connect to motor shaft. Additional lights: Use accessory power outlet.

  1. Turn off machine before connecting accessories.
  2. Mount thread stand at recommended height and distance.
  3. Connect bobbin winder drive belt to motor pulley.
  4. Install additional work lights using provided connectors.

Tip: Ensure all accessories are securely mounted and do not interfere with machine operation.

Basic Operation

Supports various fabrics and materials from light to heavy weight.

  1. Power on: Press POWER button; wait for system initialization.
  2. Material placement: Position fabric under presser foot.
  3. Start sewing: Depress foot pedal gradually to control speed.
  4. Reverse stitching: Press REVERSE button at seam ends.
  5. Needle positioning: Use NEEDLE POSITION for precise stops.
  6. Speed adjustment: Use control panel or foot pedal pressure.
  7. Thread trimming: Manual thread cutting after stitching.
  8. Pattern selection: Choose from programmed stitch patterns.

WARNING! Keep fingers away from needle area during operation. Always use proper guarding.

Maintenance Features

Automatic Lubrication: Continuous oil circulation with level monitoring. Stitch Counter: Tracks production for maintenance scheduling. Safety Clutch: Prevents damage from thread jams.

Care & Cleaning

Daily cleaning: Remove lint and dust from hook area and feed dogs. Weekly maintenance: Check oil levels and clean oil filters.

CAUTION! Disconnect power before cleaning. Use only recommended cleaning solvents.

Regulatory Information

CE Certified: Complies with European machinery directives. ISO 9001: Quality management system certified. Copyright © 2024 Mitsubishi Electric Corporation; all rights reserved. For technical support, visit www.mitsubishi-electric.com or contact +81-3-3218-2111.

Troubleshooting

SymptomPossible CauseCorrective Action
Machine won't startPower connection/safetyCheck power supply; ensure emergency stop is released; verify safety guards.
Thread breakingTension/needleAdjust thread tension; check needle for damage; verify proper threading.
Uneven stitchesTiming/tensionCheck hook timing; adjust upper and lower thread tension.
Oil leakageSeals/reservoirInspect oil seals; check reservoir connections; do not overfill.
Motor overheatingLoad/ventilationReduce sewing speed; ensure proper ventilation; check for mechanical binding.

Reset: Power cycle machine if electronic issues occur.

Service: +81-3-3218-2111; www.mitsubishi-electric.com

Mitsubishi DB-120 Industrial Sewing Machine Manual © - All Rights Reserved 2025