Marantz PMD340 Service Manual

The Marantz PMD340 is a professional portable digital recorder featuring compact design, high-quality recording capabilities, multiple input options, built-in stereo microphones, USB connectivity, SD card storage, and professional audio features. This service manual provides comprehensive technical information for service technicians including specifications, disassembly procedures, circuit diagrams, and troubleshooting guidelines.

1. Technical Specifications 2. Block Diagram Overview 3. Disassembly Procedures 4. Circuit Descriptions 5. PCB Layouts 6. Test Points & Adjustments 7. Parts List 8. Troubleshooting Flowcharts 9. Firmware Update Procedures 10. Safety Precautions 11. Service Notes

Technical Specifications

Detailed technical specifications for the Marantz PMD340 professional recorder.

Parameter	Specification
Recording Format	Linear PCM, MP3
Sampling Frequency	44.1kHz, 48kHz, 96kHz
Bit Depth	16-bit, 24-bit
Storage Media	SD/SDHC card (up to 32GB)
Input Connectors	XLR, 1/4" TRS, 3.5mm stereo mini
Output Connectors	XLR, 1/4" TRS, 3.5mm stereo mini
Power Supply	DC 6V, 4x AA batteries
Frequency Response	20Hz - 20kHz (±1dB)
Signal-to-Noise Ratio	>90dB
Dimensions	165 x 65 x 35 mm
Weight	450g (without batteries)

Block Diagram Overview

System architecture and signal flow description.

Input Stage: Microphone preamps, line inputs with phantom power
ADC Section: 24-bit analog-to-digital converters
DSP Processing: Digital signal processing for effects and filtering
Memory Control: SD card interface and buffer management
Output Stage: DAC, headphone amplifier, line outputs
Power Management: Battery monitoring and DC-DC conversion

WARNING! Always disconnect power before servicing. Use ESD protection when handling PCBs.

Disassembly Procedures

Step-by-step disassembly instructions for service access.

Remove battery cover and batteries
Remove 6 Phillips screws from bottom case
Carefully separate top and bottom cases
Disconnect ribbon cables from main board
Remove display assembly screws
Lift control board for access to main PCB

CAUTION! Handle ribbon cables carefully to avoid damage. Note cable orientation for reassembly.

Circuit Descriptions

Power Supply Circuit: DC-DC converters, battery monitoring, voltage regulation
Audio Input Stage: Balanced microphone preamps, phantom power circuitry
ADC Circuit: 24-bit sigma-delta converters, anti-aliasing filters
Digital Processing: Main DSP, memory interface, clock generation
Output Stage: DAC circuitry, headphone amplifier, line drivers
Control System: Microcontroller, button matrix, display driver

PCB Layouts

Printed circuit board layouts and component locations.

Main Board: Top and bottom layer views with component designations. Control Board: Button and display interface layout. Power Board: DC input and battery management circuitry.

Reference designators: U1-U25 (ICs), R1-R150 (resistors), C1-C200 (capacitors), L1-L10 (inductors)

Test Points & Adjustments

Service adjustment procedures and test point locations.

Power supply voltages: TP1 (+5V), TP2 (+3.3V), TP3 (+1.8V)
Reference voltages: TP4 (2.5V reference), TP5 (1.25V reference)
Clock signals: TP6 (master clock), TP7 (system clock)
Audio levels: TP8 (line input), TP9 (mic input), TP10 (headphone out)

Tip: Use calibrated test equipment for all adjustments.

Parts List

Complete list of replacement parts and components.

Part Number	Description	Qty
PMD340-MAIN	Main PCB Assembly	1
PMD340-CONTROL	Control PCB Assembly	1
PMD340-DISPLAY	LCD Display Module	1
PMD340-CASE-TOP	Top Case Assembly	1
PMD340-CASE-BOTTOM	Bottom Case Assembly	1
PMD340-JACKS	Connector Assembly	1
PMD340-KNOB	Main Control Knob	1
PMD340-BATT-COVER	Battery Cover	1

Troubleshooting Flowcharts

Systematic troubleshooting procedures for common issues.

Symptom	Possible Cause	Corrective Action
No power	Batteries, power switch, DC jack	Check battery voltage, test power switch, inspect DC jack
No audio recording	Input circuits, ADC, memory	Test input signals, check ADC voltages, verify SD card
Distorted playback	DAC, output amp, headphones	Check DAC output, test amplifier stages, verify load impedance
Display issues	Ribbon cable, display driver, contrast	Reseat ribbon cable, check display voltages, adjust contrast
Button non-response	Control board, matrix, microcontroller	Test button contacts, check matrix lines, verify microcontroller

Reset: Hold STOP + PLAY during power-on for factory reset.

Firmware Update Procedures

Step-by-step firmware update instructions.

Download latest firmware from Marantz support website
Format SD card to FAT32 file system
Copy firmware file to root directory of SD card
Insert SD card into PMD340
Hold MENU button while powering on
Follow on-screen update prompts
Do not power off during update process

WARNING! Interrupting firmware update may render unit inoperable.

Safety Precautions

Essential safety information for service personnel.

Always disconnect power before servicing. Use approved replacement parts only. Observe ESD precautions. Test unit in isolation after repair. Verify all safety certifications after service completion.

CAUTION! High voltages may be present in power supply section. Use isolation transformer when testing.

Service Notes

Additional service information and reference data.

Calibration: Requires calibrated audio test equipment
Warranty: Service seals must not be broken during warranty period
Documentation: Keep detailed service records for each repair
Parts Ordering: Use genuine Marantz parts for all replacements
Support: Technical support available at service.marantz.com

Service Contact: Marantz Professional Service Department - 1-800-526-0265