Marantz PM11S1 Service Manual

The Marantz PM11S1 is a high-end integrated amplifier featuring advanced audio circuitry, dual mono construction, high-current power supply, HDAM modules, balanced and unbalanced inputs, motorized volume control, and comprehensive protection circuits. This service manual provides detailed technical information for qualified service personnel including schematics, alignment procedures, parts lists, and troubleshooting guidelines.

1. Technical Specifications 2. Block Diagram Overview 3. Circuit Description 4. Disassembly Instructions 5. Alignment Procedures 6. Test Points & Measurements 7. Parts List 8. PCB Layouts 9. Troubleshooting Guide 10. Safety Precautions

Technical Specifications

Detailed electrical and mechanical specifications for the PM11S1 integrated amplifier.

Parameter	Specification
Power Output	100W + 100W (8Ω, 20Hz-20kHz, 0.05% THD)
Frequency Response	5Hz-100kHz (+0/-3dB)
Total Harmonic Distortion	0.005% (1kHz, 8Ω)
Input Sensitivity	200mV (LINE), 800mV (BALANCED)
Signal-to-Noise Ratio	100dB (LINE, IHF-A)
Input Impedance	47kΩ (UNBAL), 94kΩ (BAL)
Damping Factor	200 (8Ω, 1kHz)
Power Consumption	210W (rated), 0.5W (standby)
Dimensions	440 × 180 × 463mm (W×H×D)
Weight	25.5kg

Block Diagram Overview

System architecture showing signal flow and major functional blocks.

Input Selector: Relay-based switching for multiple inputs
Volume Control: Motorized ALPS potentiometer with remote operation
HDAM Modules: Marantz Hyper Dynamic Amplifier Modules for signal processing
Power Amplifier: Dual mono configuration with separate power supplies
Protection Circuit: DC detection, thermal protection, and overload protection
Power Supply: Toroidal transformer with separate windings for each channel

WARNING! High voltages present - discharge capacitors before servicing.

Circuit Description

Detailed explanation of major circuit sections and their operation.

Input Stage: JFET differential amplifier with current mirror load
Voltage Amplification: HDAM-SA2 modules for high-speed voltage gain
Driver Stage: Complementary push-pull configuration with thermal tracking
Output Stage: Triple-parallel push-pull MOSFETs for high current delivery
Power Supply: Dual mono design with separate rectification and filtering
Protection: Microprocessor-controlled protection system

CAUTION! Use only specified replacement components to maintain performance.

Disassembly Instructions

Top Cover Removal: Remove 6 Phillips screws from rear panel
Front Panel: Remove 4 screws from sides after top cover removal
Main Board Access: Remove input/output connectors and mounting screws
Power Supply: Discharge main capacitors before handling
Heat Sink Assembly: Requires complete disassembly for access
Transformer: Secured with 4 bolts through chassis

Alignment Procedures

Step-by-step adjustment procedures for optimal performance.

DC Offset Adjustment: VR101/VR102 for left/right channels (target: 0mV ±5mV)

Bias Current Adjustment: VR103/VR104 (target: 15mA ±2mA)

Protection Threshold: VR105 for DC detection level (target: ±1.5V)

Input Balance: VR106 for balanced input matching

Required equipment: Digital multimeter, oscilloscope, audio generator, dummy loads

Test Points & Measurements

Key test points and expected voltage readings.

Test Point	Location	Normal Voltage
TP1 (+B)	Main board near Q101	+65V DC
TP2 (-B)	Main board near Q102	-65V DC
TP3 (+15V)	Regulator board IC201	+15V DC
TP4 (-15V)	Regulator board IC202	-15V DC
TP5 (5V)	Control board IC301	+5V DC
TP6 (GND)	Chassis	0V

Parts List

Critical replacement components with manufacturer part numbers.

Output MOSFETs: 2SK3497/2SJ618 (matched pairs required)
Driver Transistors: 2SC2705/2SA1145
Power Supply Diodes: 10DQ10
Main Capacitors: 15,000μF/80V (Nichicon KG series)
Volume Control: ALPS RK27112A
Relays: G6B-1114P (signal), G8P-1A4P (power)

Tip: Always replace output devices in complementary pairs.

PCB Layouts

Printed circuit board diagrams and component locations.

Main Amplifier Board: Component side and solder side views with reference designators

Power Supply Board: Layout showing transformer connections and rectifier section

Control Board: Microprocessor and interface circuitry

Input Selector Board: Relay matrix and input switching

WARNING! Observe electrostatic discharge precautions when handling PCBs.

Troubleshooting Guide

Symptom	Possible Cause	Corrective Action
No power	Fuse blown, power switch	Check F101/F102 (8A); verify switch operation
Protection mode	DC offset, short circuit	Measure output DC; check speaker terminals
Distorted output	Bias current, damaged devices	Adjust bias; check output MOSFETs
No sound one channel	Input relay, amplifier stage	Check RY101/RY102; trace signal path
Volume control issues	Motor, position sensor	Verify motor voltage; check position feedback

Reset: Power cycle to clear protection lockout.

Service: Authorized Marantz service centers only.