Marantz PMD661 Service Manual

The Marantz PMD661 is a professional portable solid-state recorder featuring high-quality audio recording capabilities, built-in stereo microphones, XLR inputs with phantom power, USB connectivity, SD card storage, and multiple recording formats including WAV and MP3. This service manual provides comprehensive technical information for maintenance, repair, and troubleshooting of the PMD661 recorder. Below are key sections covering specifications, disassembly procedures, circuit diagrams, calibration, and troubleshooting.

1. Technical Specifications 2. Mechanical Disassembly 3. Circuit Diagrams 4. PCB Layouts 5. Calibration Procedures 6. Component Replacement 7. Power Supply Section 8. Audio Input/Output Circuits 9. Firmware Update 10. Safety Precautions 11. Troubleshooting Guide

Technical Specifications

Key technical parameters and performance characteristics of the Marantz PMD661 recorder.

Parameter	Specification
Recording Format	WAV (16/24-bit), MP3 (32-320 kbps)
Sample Rates	44.1 kHz, 48 kHz, 96 kHz
Input Connectors	2 x XLR/TRS combo, 3.5mm stereo mini
Output Connectors	3.5mm stereo, RCA line out
Phantom Power	+48V on XLR inputs
Storage Media	SD/SDHC card (up to 32GB)
Power Supply	6 x AA batteries, DC 9V input
Frequency Response	20Hz - 20kHz (±1dB)
Signal-to-Noise Ratio	>90dB
THD+N	<0.01%

Mechanical Disassembly

Step-by-step procedure for disassembling the PMD661 unit for service access.

Remove battery compartment cover and batteries.
Unscrew 8 case screws (4 on bottom, 2 on each side).
Carefully separate top and bottom case halves.
Disconnect internal ribbon cables from main board.
Remove front panel assembly for display access.
Extract main PCB for component-level service.

WARNING! Use proper ESD protection. Handle ribbon cables with care to avoid damage.

Circuit Diagrams

Complete schematic diagrams for all major circuit sections.

Main Processor Circuit: Central control and digital processing
Audio Input Stage: Microphone preamps and line inputs
ADC/DAC Section: Analog-to-digital and digital-to-analog conversion
Power Management: Battery and DC power regulation
Memory Interface: SD card and internal flash memory
USB Interface: Computer connectivity and data transfer
Display Driver: LCD control and backlight circuit

PCB Layouts

Printed circuit board layouts with component placement and routing.

Main Board: Double-sided PCB with surface mount and through-hole components. Key ICs: Main processor, audio codec, power regulators, memory controllers.

Front Panel Board: Contains buttons, display connector, status LEDs.

I/O Board: XLR connectors, phantom power circuitry, output jacks.

Calibration Procedures

Factory calibration methods for optimal audio performance.

Input level calibration: Apply 1kHz reference signal, adjust trim pots for specified levels.
Output level calibration: Verify line output levels match specifications.
Phantom power verification: Check +48V supply stability under load.
Battery calibration: Reset battery meter for accurate remaining time display.
Clock calibration: Adjust RTC crystal for time accuracy.

CAUTION! Use calibrated test equipment. Follow ESD precautions.

Component Replacement

Guidelines for replacing common service components.

Component	Part Number	Replacement Notes
Main Processor	PMD661-MP1	Requires firmware reload after replacement
Audio Codec IC	PMD661-AC1	Pre-calibrated unit recommended
LCD Display	PMD661-LCD1	Handle with care, fragile connector
Power Regulators	PMD661-PWR1	Check surrounding components for damage
XLR Connectors	PMD661-XLR1	Ensure proper grounding after replacement

Power Supply Section

Detailed analysis of power distribution and regulation circuits.

Battery input: 6 x AA cells (9V nominal) through protection circuit. DC input: 9V regulated external supply. Main regulators: +3.3V for digital, ±5V for analog, +48V for phantom power.

Power Management IC: Controls battery charging, power sequencing, and low-battery detection.

Audio Input/Output Circuits

Circuit analysis of audio signal path and processing.

Microphone preamps: Low-noise op-amps with adjustable gain
Line inputs: Balanced/unbalanced switching capability
Phantom power: Regulated +48V supply with current limiting
ADC section: 24-bit sigma-delta converters
Headphone amp: Dedicated driver with volume control
Line outputs: Balanced capability via separate drivers

Tip: Check input capacitors for DC leakage in noisy preamp circuits.

Firmware Update

Procedures for updating unit firmware and recovery methods.

Download latest firmware from Marantz support site
Format SD card as FAT32 and copy firmware file
Insert card, hold MENU while powering on
Follow on-screen update prompts
Do not power off during update process

WARNING! Interrupted updates may brick the unit. Use fully charged batteries.

Safety Precautions

Essential safety guidelines for service technicians.

Always disconnect power before servicing. Use ESD protection when handling PCBs. Note that phantom power circuits contain hazardous voltages. Replace fuses only with specified ratings.

CAUTION! High voltages present in power supply section. Capacitors may retain charge after power removal.

Troubleshooting Guide

Symptom	Possible Cause	Corrective Action
No power	Batteries/DC input	Check battery polarity; verify DC jack connection; test fuse F1
No audio recording	Input selection/mics	Verify input source selection; check microphone connections; test preamp IC
Distorted audio	Input levels/ADC	Reduce input gain; check ADC reference voltages; test op-amps
SD card errors	Card format/damage	Reformat card; clean contacts; replace card reader assembly
Display issues	Connector/backlight	Reseat display cable; check backlight inverter; replace LCD

Factory Reset: Hold STOP + PLAY while powering on to reset all settings.

Service Support: Contact Marantz professional audio division for technical assistance.