Janome MC350E Service Manual

The Janome MC350E is a computerized sewing machine featuring 50 built-in stitches, one-step buttonhole, automatic needle threader, drop feed for free-motion sewing, adjustable stitch length and width, built-in needle plate thread cutter, and easy reverse stitching. This service manual provides comprehensive technical information for maintenance, troubleshooting, and repair procedures. Below are key sections covering technical specifications, maintenance procedures, troubleshooting, and service guidelines.

1. Technical Specifications 2. Safety Precautions 3. Maintenance Procedures 4. Disassembly Instructions 5. Electrical System 6. Mechanical Components 7. Troubleshooting Guide 8. Calibration Procedures 9. Parts List 10. Service Tools 11. Warranty Information

Technical Specifications

Key technical parameters and operating characteristics of the Janome MC350E sewing machine.

Specification	Description
Stitch Types	50 built-in stitches including utility, decorative, and stretch stitches
Buttonhole	One-step automatic buttonhole
Stitch Length	Adjustable up to 5mm
Stitch Width	Adjustable up to 7mm
Needle Positions	Multiple needle positions available
Presser Foot Pressure	Adjustable for different fabric types
Motor Power	85W DC motor
Maximum Sewing Speed	820 stitches per minute
Bobbin System	Top loading, jam resistant
Power Requirements	110-120V, 60Hz

Safety Precautions

Essential safety guidelines for service technicians and maintenance personnel.

Always disconnect power before performing any service or maintenance.
Use proper tools and follow specified torque values for all fasteners.
Wear safety glasses when working with springs or under tension components.
Handle electronic components with anti-static precautions.
Ensure proper reassembly and function testing before returning to customer.

WARNING! High voltage present in power supply unit. Only qualified technicians should service electrical components.

Maintenance Procedures

Routine maintenance schedule and procedures for optimal machine performance.

Daily cleaning: Remove lint and dust from bobbin area and feed dogs.
Weekly lubrication: Apply sewing machine oil to designated points.
Monthly inspection: Check belt tension, motor brushes, and electrical connections.
Quarterly calibration: Verify stitch timing and needle bar alignment.
Annual service: Complete disassembly, cleaning, and reassembly.

CAUTION! Use only Janome-approved lubricants and replacement parts.

Disassembly Instructions

Housing Removal: Remove 6 screws from bottom plate and 2 from rear cover.
Motor Access: Remove belt cover and disconnect power leads.
Needle Bar Mechanism: Remove front cover and disconnect linkage rods.
Feed Dog System: Remove throat plate and feed dog cover.
Electronic Control Board: Disconnect all connectors before removal.
Bobbin Case Assembly: Remove shuttle race and hook assembly.
Stitch Selection Mechanism: Access through top cover removal.
Foot Controller: Inspect wiring and potentiometer function.

Electrical System

Electrical components and circuit descriptions for troubleshooting and repair.

Main Components: Power supply board, main control board, motor control circuit, LED display, stitch selection buttons, foot pedal controller.

Circuit Analysis: Power input filtering, DC motor drive circuit, microprocessor control, sensor inputs, display driver. Voltage Specifications: +5V for logic circuits, +12V for motor control, +24V for display backlight. Testing Procedures: Use multimeter to verify voltage levels at test points. Component Replacement: Desoldering techniques for SMD components.

Mechanical Components

Detailed mechanical assembly and adjustment procedures.

Turn off power and remove needle before servicing mechanical components.
Refer to exploded diagrams for proper assembly sequence.
Use alignment tools for precise component positioning.
Verify timing marks on gears and cams during reassembly.

Tip: Take photos during disassembly for reference during reassembly.

Troubleshooting Guide

Common problems and their solutions for the MC350E sewing machine.

Machine won't start: Check power cord, foot controller, and main fuse.
Poor stitch quality: Verify needle condition, thread tension, and timing.
Motor runs but no stitch: Inspect drive belt and clutch mechanism.
Error codes displayed: Refer to error code chart in service manual.
Buttonhole malfunction: Check buttonhole sensor and cam mechanism.
Thread breaking: Examine needle plate, tension disks, and thread path.
Uneven feeding: Inspect feed dogs and presser foot pressure.
Noise during operation: Check for worn bearings or loose components.

WARNING! Always diagnose completely before replacing components.

Calibration Procedures

Precision adjustment and calibration methods for optimal performance.

Calibration Type	Procedure	Tolerance
Needle Bar Height	Adjust set screw at top of needle bar	±0.1mm
Hook Timing	Align timing marks on hook drive gear	±1°
Feed Dog Height	Adjust lift cam position	0.8-1.0mm above plate
Thread Tension	Calibrate tension spring pressure	40-60g tension
Motor Speed	Adjust potentiometer on control board	820±10 SPM

Parts List

Complete list of replacement parts with part numbers and descriptions.

CAUTION! Use only genuine Janome replacement parts for optimal performance and safety.

Service Tools

Specialized tools required for proper service and maintenance.

Alignment Tools: Needle bar alignment gauge, hook timing tool
Measurement Tools: Digital caliper, tension gauge, tachometer
Special Screwdrivers: JIS screwdrivers for Japanese standard screws
Lubrication: Sewing machine oil, grease applicator
Electronic Tools: Multimeter, oscilloscope, soldering station
Cleaning Tools: Lint brushes, compressed air, cleaning swabs

Warranty Information

Janome MC350E warranty terms and service center requirements. 25-year limited warranty on mechanical parts, 5-year limited warranty on electronic components, 1-year limited warranty on labor. Warranty valid only when serviced by authorized Janome service centers. For technical support, contact Janome America at 1-800-631-0183 or visit www.janome.com.

Troubleshooting

Symptom	Possible Cause	Corrective Action
Machine doesn't start	Power supply issues	Check power cord, outlet, and main fuse; verify foot controller connection.
Thread breaking frequently	Needle/tension issues	Replace needle; check thread tension; inspect needle plate for burrs.
Uneven stitches	Timing/tension problems	Verify hook timing; adjust upper and lower thread tension.
Motor runs but no movement	Drive mechanism	Inspect drive belt; check clutch mechanism; examine handwheel set screw.
Error codes displayed	Electronic faults	Refer to error code chart; check sensor connections; reset control board.

Reset Procedure: Unplug machine for 5 minutes to reset electronic controls.

Service Centers: 1-800-631-0183; www.janome.com