The Marantz PMD351 is a professional portable cassette recorder featuring three-head configuration, Dolby B/C noise reduction, manual recording level control, built-in condenser microphone, line inputs/outputs, microphone inputs with phantom power, cue and review functions, pitch control, and auto tape selector. Designed for professional field recording and broadcast applications. Below are key sections for technical specifications, disassembly procedures, circuit diagrams, alignment instructions, troubleshooting, and parts list.
Key technical parameters and performance characteristics of the Marantz PMD351 professional cassette recorder.
| Parameter | Specification |
|---|---|
| Heads | 3-head system (erase, record, playback) |
| Noise Reduction | Dolby B, Dolby C |
| Frequency Response | 30Hz - 18kHz (Metal tape) |
| Signal-to-Noise Ratio | 72dB with Dolby C |
| Wow & Flutter | 0.08% (WRMS) |
| Inputs | Line IN, Mic IN (XLR/phone), Ext Mic |
| Outputs | Line OUT, Headphone |
| Power Supply | 6V DC (4x AA batteries or AC adapter) |
| Dimensions | 180 x 72 x 32 mm |
| Weight | 520g (without batteries) |
Step-by-step instructions for safely disassembling the Marantz PMD351 for service and repair.
WARNING! Always disconnect power before disassembly. Handle ribbon cables with care to avoid damage.
Complete schematic diagrams for all circuit boards and subsystems.
Detailed procedures for mechanical and electrical alignment of tape transport and audio circuits.
CAUTION! Use proper test equipment and alignment tapes. Document all adjustments.
System block diagrams showing signal flow and functional relationships between circuits.
Audio Signal Path: Input selection → Mic preamp/Line in → Record amplifier → Record head → Playback head → PB amplifier → Dolby NR → Output amplifier → Line out/Headphone
Control System: Function switches → Microprocessor → Motor control → Display drivers → Mode indicators
Power Distribution: DC input → Voltage regulation → ± supplies for audio circuits → Motor power → Logic power
Detailed mechanical drawings and assembly instructions for transport mechanism.
Tip: Lubricate sliding parts with specified grease only. Do not overlubricate.
Test point locations and adjustment procedures for all electronic circuits.
WARNING! Use calibrated test equipment. Follow electrostatic discharge precautions.
Systematic approach to diagnosing and repairing common problems.
| Symptom | Possible Cause | Corrective Action |
|---|---|---|
| No power | Batteries/DC jack | Check battery polarity; test DC jack; verify power switch |
| No audio output | Output stage/headphone jack | Test headphone output; check output IC; verify volume control |
| Poor recording | Record head/bias | Clean record head; check bias oscillator; verify record switches |
| Transport not working | Motor/belt/control | Test motor voltage; check drive belt; verify mode switches |
| Speed variation | Motor/capstan | Clean capstan/pinch roller; check motor regulator; test FG signal |
Reset: Power cycle unit. Check all mechanical linkages.
Complete listing of all components with manufacturer part numbers.
Essential safety information for service technicians.
CAUTION! Disconnect power before servicing. Use isolation transformer when testing live circuits. Observe ESD precautions with CMOS devices.
Additional technical information and service tips from Marantz engineering.
Field modifications: Revised bias trap adjustment procedure (Service Bulletin 351-1). Common issues: Pinch roller arm spring tension critical for proper tape handling. Component substitutions: Approved alternate sources for obsolete components. Firmware updates: No user-serviceable firmware in this model.
Service Contacts: Marantz Professional Service Department - [email protected]