Marantz PMD221 Service Manual

The Marantz PMD221 is a professional portable cassette recorder featuring 3-head configuration, Dolby B/C noise reduction, pitch control, line/mic inputs with level controls, built-in condenser microphone, VU meters, auto/manual record level, cue/review functions, and operates on AC power or batteries. Below are key sections for technical specifications, circuit descriptions, alignment procedures, troubleshooting, and parts list.

1. Technical Specifications 2. Block Diagram Overview 3. Circuit Descriptions 4. Mechanical Disassembly 5. Electrical Adjustments 6. Head Alignment 7. Troubleshooting Guide 8. Parts List 9. Schematics 10. Safety Precautions

Technical Specifications

Key performance parameters and operating characteristics of the PMD221 recorder.

Parameter	Specification
Frequency Response	30Hz - 16kHz (±3dB) with Type II tape
Signal-to-Noise Ratio	62dB (Dolby C), 58dB (Dolby B)
Wow & Flutter	0.08% (WRMS)
Input Sensitivity	Mic: 0.5mV, Line: 50mV
Output Level	Line: 0.5V, Headphone: 30mW
Power Requirements	AC 120V/230V, DC 6V (4xAA batteries)
Dimensions	228 x 134 x 58 mm
Weight	1.2 kg (with batteries)
Heads	Erase, Record, Playback (3-head system)
Motors	DC servo capstan motor, DC reel motor

Block Diagram Overview

System architecture and signal flow description.

Input Stage: Mic/Line selector, input amplifiers with level controls
Record Amplifier: Dolby B/C encoding, bias oscillator, record EQ
Playback Amplifier: Dolby B/C decoding, playback EQ, output stage
Motor Control: Servo circuit for capstan speed stability
Power Supply: Voltage regulation for analog and digital sections

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

Circuit Descriptions

Detailed analysis of major circuit blocks and their functions.

Record Amplifier Circuit: IC201 handles input amplification and Dolby encoding
Playback Amplifier Circuit: IC202 provides Dolby decoding and output amplification
Bias Oscillator: Transistor Q301 generates 85kHz bias frequency
Motor Servo: IC401 controls capstan speed via phase comparison
Power Supply: Regulated ±12V and +5V rails from AC adapter or batteries

CAUTION! Use proper grounding when testing live circuits.

Mechanical Disassembly

Case Removal: Remove 6 screws from bottom case, carefully separate halves
Main Board Access: Remove 4 mounting screws, disconnect ribbon cables
Transport Mechanism: Remove belt cover, motor mounting screws
Head Assembly: Remove shield, head mounting screws for replacement
Button Assembly: Remove front panel, carefully detach button membrane

Electrical Adjustments

Calibration procedures using test equipment.

Required Equipment: Audio generator, oscilloscope, VTVM, test tape

Playback Level: Adjust VR202 for 0dB with 315Hz reference tape. Record Level: Adjust VR201 for 0dB with 315Hz 0VU input. Bias Current: Adjust VR301 for flattest frequency response. Dolby Level: Adjust VR203 for proper tracking alignment.

Head Alignment

Azimuth, height, and zenith adjustment procedures.

Azimuth: Play 10kHz test tape, adjust screw for maximum output
Height: Ensure tape contact across entire head surface
Zenith: Adjust for minimal high-frequency loss at tape edges
Head Replacement: Use alignment tape after installing new heads
Contact Check: Verify proper tape-to-head contact pressure

Tip: Use non-magnetic tools for head adjustments.

Troubleshooting Guide

Common symptoms and repair procedures.

Symptom	Possible Cause	Corrective Action
No power	Fuse, power switch, regulator	Check F101, Q501, IC502 voltages
No playback	Head connection, PB amp	Check head wires, IC202 voltages
No record	Bias oscillator, REC amp	Check Q301, IC201, bias voltage
Speed variation	Motor, servo circuit	Check IC401, speed pot VR401
Distorted audio	Capacitors, transistors	Check electrolytic caps, output stage

Parts List

Critical replacement components and part numbers.

Component	Part Number	Description
Playback Head	PMD221-001	Record/Playback combination head
Erase Head	PMD221-002	AC erase head assembly
Capstan Motor	PMD221-003	DC servo capstan motor
Main Belt	PMD221-004	Flat drive belt 65mm
IC201	LA3160	Dual preamplifier IC
IC202	LA3161	Dolby processor IC
Power Transformer	PMD221-005	AC power transformer

Schematics

Complete circuit diagrams available in separate section.

Main Board Schematic: Shows complete audio and control circuits. Power Supply Schematic: AC/DC conversion and regulation. Motor Control Schematic: Servo circuit and speed control. Mechanical Layout: Transport mechanism and switch locations.

NOTE: Refer to full-size schematics for detailed component values and connections.

Safety Precautions

Service safety requirements and ESD protection.

Always disconnect AC power before servicing. Use isolation transformer when testing live circuits. Observe ESD precautions with CMOS components. Replace safety-critical components with identical parts. Verify proper grounding after repairs.

WARNING! Line voltage present in power supply section. Use extreme caution.