Marantz PM 4200 Service Manual

The Marantz PM 4200 is a high-quality stereo integrated amplifier featuring 60 watts per channel, MM/MC phono input, CD direct input, tone controls, loudness compensation, and A/B speaker selection. This service manual provides comprehensive technical information for service technicians, including schematics, alignment procedures, parts list, and troubleshooting guidelines for proper maintenance and repair.

1. Technical Specifications 2. Block Diagram 3. Circuit Description 4. Disassembly Instructions 5. Alignment Procedures 6. Voltage Measurements 7. Parts List 8. PCB Layouts 9. Troubleshooting Guide 10. Safety Precautions 11. Service Notes

Technical Specifications

Detailed electrical and mechanical specifications for the Marantz PM 4200 integrated amplifier.

Parameter	Specification
Power Output	60W + 60W (8Ω, 20Hz-20kHz, 0.08% THD)
Total Harmonic Distortion	0.08% (20Hz-20kHz at rated output)
Frequency Response	5Hz-50kHz (+0/-3dB)
Input Sensitivity	Phono MM: 2.5mV, CD: 150mV, Tuner: 150mV
Signal-to-Noise Ratio	Phono MM: 80dB, CD: 100dB
Tone Control	Bass: ±10dB at 100Hz, Treble: ±10dB at 10kHz
Power Supply	AC 120V/230V, 50/60Hz
Dimensions	440mm (W) x 130mm (H) x 330mm (D)
Weight	8.5 kg
Speaker Impedance	4-16Ω

Block Diagram

System overview showing signal flow and major functional blocks.

Input Selector: Phono, CD, Tuner, Aux, Tape 1, Tape 2
Phono Equalizer: RIAA equalization for MM/MC cartridges
Tone Control: Bass and treble adjustment circuits
Volume Control: ALPS motorized potentiometer
Power Amplifier: Complementary symmetry push-pull output stage
Power Supply: Toroidal transformer with regulated supplies
Protection Circuit: DC detection and thermal protection

NOTE: Refer to schematic diagram for detailed circuit connections.

Circuit Description

Detailed explanation of major circuit sections and their operation.

Power Supply: Toroidal transformer with dual secondary windings, bridge rectifiers, and large filter capacitors
Phono Stage: Low-noise JFET input with RIAA equalization network
Preamplifier: High slew rate op-amps with low distortion characteristics
Power Amplifier: Complementary Darlington output transistors with current mirror bias
Protection Circuit: Relay-based speaker protection with DC offset detection
Control Circuit: Microprocessor-based input selection and volume control

CAUTION! High voltages present in power supply section. Disconnect from mains before servicing.

Disassembly Instructions

Step-by-step procedure for accessing internal components.

Remove top cover: Unscrew 6 Phillips screws on top panel
Remove front panel: Detach 4 screws at sides and bottom
Access main board: Remove 8 screws securing main PCB
Remove power supply: Disconnect all wiring and remove 4 mounting screws
Access volume control: Remove front knob and mounting nut

WARNING! Always discharge power supply capacitors before working on amplifier circuits.

Alignment Procedures

Factory adjustment procedures for optimal performance.

DC Offset: Adjust VR101 for 0mV ±5mV at speaker terminals
Bias Current: Adjust VR102 for 15mA across emitter resistors
Phono Balance: Adjust for equal output from both channels
Protection Delay: Verify 3-5 second delay before relay engagement

Required Equipment: Digital multimeter, oscilloscope, audio generator, dummy load

Voltage Measurements

Reference voltage measurements at key test points.

Test Point	Voltage (DC)	Tolerance
TP+ (Positive Rail)	+42V	±2V
TP- (Negative Rail)	-42V	±2V
TP A (Op-amp Supply)	±15V	±0.5V
TP B (Phono Stage)	+24V	±1V
Output Offset	0mV	±10mV

NOTE: All measurements with no signal input and volume at minimum.

Parts List

Complete list of components with manufacturer part numbers.

Reference	Description	Part Number
Q101-Q104	Output Transistor 2SC3281/2SA1302	MAR-4200-001
IC101, IC102	Op-amp NJM4558	MAR-4200-002
RY101	Protection Relay	MAR-4200-003
T101	Toroidal Transformer	MAR-4200-004
C101, C102	Main Filter Cap 10000μF/63V	MAR-4200-005

NOTE: Use only genuine Marantz replacement parts for optimal performance.

PCB Layouts

Printed circuit board diagrams for main board and power supply.

Main Amplifier Board: Component placement and trace routing
Power Supply Board: Rectifier and filter component layout
Front Panel Board: Switch and indicator LED positions
Grounding Scheme: Star grounding points and signal returns

Tip: Check for cracked solder joints, especially on heavy components.

Troubleshooting Guide

Common problems and their solutions.

Symptom	Possible Cause	Corrective Action
No power	Fuse blown, power switch	Check F101, F102; test power switch
No sound	Protection relay, output transistors	Check relay operation; test output devices
Distortion	Bias current, damaged transistors	Adjust bias; replace output pairs
Hum/buzz	Ground loops, filter capacitors	Check grounding; replace filter caps
Intermittent operation	Cold solder joints, connectors	Resolder joints; clean connectors

Reset: Power cycle amplifier to reset protection circuit.

Safety Precautions

Essential safety procedures for service personnel.

Always disconnect from mains before servicing. Use isolation transformer when testing live circuits. Discharge large capacitors before handling. Wear safety glasses when soldering. Follow ESD precautions with semiconductors.

WARNING! Lethal voltages present in power supply. Only qualified technicians should perform repairs.

Service Notes

Additional technical information and service tips.

Use thermal compound when replacing output transistors
Check speaker relay contacts for oxidation
Verify proper heat sink mounting pressure
Clean volume and selector controls with contact cleaner
Update service bulletins available from Marantz service portal

Service Support: Contact Marantz technical support for complex issues.