Marantz 6350Q Service Manual

The Marantz 6350Q is a professional-grade turntable featuring quartz-controlled direct drive system, fully automatic operation, adjustable tonearm with viscous-damped cueing, anti-skating control, variable pitch control (±10%), stroboscopic speed indicator, and built-in phono preamplifier. Designed for audiophile performance with low wow and flutter, high signal-to-noise ratio, and precision engineering. Below are key sections for technical specifications, service procedures, adjustments, troubleshooting, and maintenance.

1. Technical Specifications 2. Service Precautions 3. Disassembly Procedures 4. Circuit Diagrams 5. Adjustment Procedures 6. Mechanical Components 7. Electrical Components 8. Troubleshooting Guide 9. Parts List 10. Maintenance Schedule 11. Service Notes

Technical Specifications

Key technical parameters: Drive system, speed accuracy, wow and flutter, signal-to-noise ratio, tonearm specifications.

Parameter	Specification
Drive System	Quartz-controlled direct drive
Speeds	33-1/3, 45, 78 RPM
Wow and Flutter	0.025% WRMS
Signal-to-Noise Ratio	78 dB (DIN B)
Tonearm Type	Static balanced S-shaped
Effective Length	228.6 mm
Overhang	15.5 mm
Tracking Force Range	0-3 grams
Anti-skating Range	0-3 grams
Power Requirements	120V AC, 60Hz, 8W

Service Precautions

Important safety procedures before servicing.

Disconnect power: Always unplug from AC outlet before servicing.
Static protection: Use anti-static wrist strap when handling circuit boards.
Component handling: Avoid excessive force on mechanical components.
Test equipment: Use calibrated instruments for adjustments.

WARNING! High voltages present in power supply section. Discharge capacitors before servicing.

Disassembly Procedures

Step-by-step disassembly instructions for service access.

Remove platter: Lift straight up after removing mat.
Remove bottom cover: Remove 6 Phillips screws from underside.
Tonearm assembly: Remove hinge screws and carefully lift assembly.
Main board access: Remove mounting screws and disconnect connectors.

CAUTION! Handle tonearm assembly with care to avoid damage to bearings and wiring.

Circuit Diagrams

Main Power Supply: Transformer, rectifier, and regulation circuits.
Motor Drive Circuit: Quartz PLL control system for precise speed.
Control Logic: Microprocessor-based automation control.
Phono Preamp: RIAA equalization circuit with low-noise design.
Speed Control: Variable pitch control circuitry.
Strobe Circuit: LED stroboscopic speed indicator.
Connector Layout: All internal connector positions and pinouts.

Adjustment Procedures

Critical adjustments for optimal performance.

Speed Calibration: Adjust VR301 for 33-1/3 RPM, VR302 for 45 RPM using stroboscope.

Tonearm: Vertical tracking force adjustment, anti-skating calibration, cueing damping adjustment. Motor: PLL lock adjustment, torque adjustment. Electronics: Phono preamp gain adjustment, output level calibration.

Mechanical Components

Platter assembly, tonearm mechanism, auto-return system, cueing mechanism.

Inspect all mechanical parts for wear or damage.
Lubricate specified points with recommended lubricants.
Check belt condition (if applicable) and replace if worn.
Verify smooth operation of all moving parts.

Tip: Use only manufacturer-specified lubricants to avoid damage.

Electrical Components

Testing and replacement procedures for electronic components.

Power supply: Check all DC voltages against specifications.
Motor drive: Test Hall sensor outputs and drive waveforms.
Control circuits: Verify microprocessor operation and sensor inputs.
Audio circuits: Test phono preamp frequency response and distortion.

WARNING! Always use exact replacement components to maintain performance specifications.

Troubleshooting Guide

Symptom	Possible Cause	Corrective Action
No power	Power cord, fuse, switch	Check AC input, replace fuse F801, test power switch.
Incorrect speed	PLL circuit, motor	Adjust speed pots VR301/302, check IC501 PLL lock.
No auto-return	Sensor, mechanism	Check end-of-record sensor, inspect return mechanism.
Motor not starting	Drive circuit, Hall sensors	Test motor drive voltages, check Hall sensor outputs.
No audio output	Preamp, cables	Test phono preamp IC701, check RCA cables and connections.

Reset: Power cycle to reset microprocessor if control functions erratic.

Parts List

Complete listing of all components with part numbers.

Maintenance Schedule

Regular maintenance procedures for long-term reliability.

Every 500 hours: Clean and lubricate mechanical parts. Every 1000 hours: Check and calibrate speed accuracy. As needed: Replace stylus, clean contacts.

CAUTION! Use only manufacturer-approved cleaning solutions and lubricants.

Service Notes

Additional service information and special procedures.

Factory calibration settings, alignment procedures, special tool requirements, warranty service procedures. For technical support, contact authorized Marantz service centers. Document all adjustments made during service.