Marantz 2130 Service Manual

The Marantz 2130 is a professional stereo tuner featuring advanced FM/AM reception capabilities, quartz PLL synthesized tuning, 30 station presets, signal strength meter, center channel tuning, and high-fidelity audio output. This service manual provides comprehensive technical information for service technicians, including schematics, alignment procedures, troubleshooting guides, and parts lists.

1. Technical Specifications 2. Block Diagram Overview 3. Circuit Description 4. Alignment Procedures 5. Test Points & Voltages 6. Troubleshooting Guide 7. Parts List & Replacements 8. PCB Layouts 9. Mechanical Assembly 10. Safety Precautions 11. Service Notes

Technical Specifications

Complete electrical and performance specifications for the Marantz 2130 stereo tuner.

Parameter	Specification
Tuning Range	FM: 87.5-108 MHz, AM: 530-1710 kHz
Usable Sensitivity	FM: 10.3 dBf (1.8 μV), AM: 300 μV/m
Signal-to-Noise Ratio	FM: 80 dB, AM: 45 dB
Total Harmonic Distortion	FM: 0.15%, AM: 0.8%
Capture Ratio	FM: 1.5 dB
Selectivity	FM: 70 dB, AM: 30 dB
Image Rejection	FM: 70 dB, AM: 45 dB
Output Voltage	500 mV (fixed), 0-2V (variable)
Power Requirements	120V AC, 60Hz, 15W
Dimensions	440 x 125 x 340 mm (WxHxD)

Block Diagram Overview

System architecture and signal flow description.

RF Amplifier Stage: FM/AM front-end amplification and filtering
Mixer/Oscillator: Quartz PLL synthesized local oscillator
IF Stages: 10.7 MHz FM IF, 450 kHz AM IF with ceramic filters
Detector Circuits: FM quadrature detector, AM envelope detector
Stereo Decoder: PLL stereo demodulator with 19 kHz pilot
Audio Output: Buffer amplifiers and output stages
Control System: Microprocessor control for tuning and display

NOTE: Refer to schematic diagrams for detailed circuit analysis.

Circuit Description

Detailed analysis of major circuit sections and their operation.

RF Input Stage: Dual-gate MOSFET for FM, bipolar transistor for AM with tracking filters
PLL Synthesizer: TC9121P IC with 7.2 MHz reference crystal, programmable dividers
FM IF System: LA1235 IC with limiter amplification, quadrature detection, and meter drives
Stereo Decoder: LA3401 IC with VCO, 76 kHz divider, and stereo/mono switching
Power Supply: Transformer with ±12V and +5V regulated outputs
Display Driver: Frequency display and signal strength meter circuits

Alignment Procedures

Step-by-step alignment instructions using proper test equipment.

FM Front-End Alignment: Adjust RF coils L1, L2 for maximum sensitivity at 98 MHz
FM IF Alignment: Align T1, T2, T3 for symmetrical S-curve and minimum distortion
Stereo Decoder Alignment: Adjust VR301 for zero beat at 19 kHz, T301 for separation
AM Alignment: Adjust oscillator and antenna trimmers for tracking across band
Meter Calibration: Adjust VR101 for accurate signal strength indication

CAUTION! Use non-metallic alignment tools and follow exact procedures.

Test Points & Voltages

Critical test points and expected voltage measurements.

Test Point	Description	Normal Voltage
TP1	+12V Regulated	+12.0V ±0.5V
TP2	-12V Regulated	-12.0V ±0.5V
TP3	+5V Logic Supply	+5.0V ±0.1V
TP4	FM Detector Output	0V DC (center)
TP5	Stereo Pilot	19 kHz, 50 mVpp
TP6	VCO Control Voltage	2.5-8.5V (varies with station)

Troubleshooting Guide

Common symptoms and diagnostic procedures.

Symptom	Possible Cause	Corrective Action
No reception	Power supply, RF stage	Check TP1, TP2 voltages; verify antenna input
Weak FM reception	RF amplifier, alignment	Check Q101 drain voltage; realign front-end
No stereo indicator	Decoder IC, pilot circuit	Verify 19 kHz at TP5; check LA3401 voltages
Display not working	Microprocessor, drivers	Check +5V supply; verify clock crystal
Station drift	PLL circuit, reference crystal	Measure VCO stability; replace X101 if needed

Reset: Power cycle unit; check all supply voltages first.

Parts List & Replacements

Critical components and replacement part numbers.

IC101: LA1235 (FM IF) - Replacement: LA1235N
IC201: LA3401 (Stereo Decoder) - Replacement: LA3401N
IC301: TC9121P (PLL Synthesizer) - Replacement: TC9121P
Q101: 3SK74 (FM RF Amp) - Replacement: 3SK74 or BF998
X101: 7.2 MHz Crystal - Replacement: 7.2 MHz HC49/U
Power Transformer: PT-254 - Replacement: PT-254 or equivalent

NOTE: Use exact replacements for critical RF components.

PCB Layouts

Printed circuit board diagrams and component locations.

Main Board (PWB-100): Contains tuner, IF, and decoder circuits
Front Panel Board (PWB-200): Display, controls, and microprocessor
Power Supply Board (PWB-300): Rectification and voltage regulation
Shielding: RF compartment shielding and grounding points

WARNING! Observe ESD precautions when handling PCBs.

Mechanical Assembly

Disassembly and reassembly instructions.

Remove rear panel screws and carefully slide chassis out
Disconnect front panel ribbon cables before full separation
Note orientation of RF shielding cans during reassembly
Ensure proper grounding of all shield covers
Verify tuning capacitor clearance and mechanical stops

CAUTION! Handle tuning capacitor carefully to avoid damage.

Safety Precautions

Important safety information for service personnel.

Always disconnect AC power before servicing
Use isolation transformer when testing live circuits
Observe high voltage areas in power supply
Replace safety critical components with exact specifications
Verify proper grounding and insulation after service

WARNING! Lethal voltages present - exercise extreme caution.

Service Notes

Additional technical notes and service tips.

Area	Service Note
PLL Lock Issues	Check VCO varactor diode D101 and loop filter C115, C116
Muting Problems	Verify Q104, Q105 operation; check detector output
Display Segment Issues	Check driver transistors Q401-Q414; ribbon connections
AM Reception Poor	Verify antenna coil L201; check IC101 AM section
Hum in Audio	Check power supply filtering C301-C304; grounding

Service Support: Refer to factory service bulletins for updates.