Marantz Model 19 Service Manual

The Marantz Model 19 is a classic stereo receiver from the golden age of hi-fi audio, featuring vacuum tube technology, AM/FM tuner, phono inputs, tape monitor, and exceptional audio performance. This service manual covers technical specifications, circuit diagrams, alignment procedures, troubleshooting, and maintenance guidelines for qualified service technicians.

1. Technical Specifications 2. Circuit Description 3. Alignment Procedures 4. Tube Complement 5. Voltage Measurements 6. Schematic Diagrams 7. Parts List 8. Mechanical Assembly 9. Troubleshooting Guide 10. Safety Precautions 11. Service Notes

Technical Specifications

Complete technical specifications for the Marantz Model 19 stereo receiver.

ParameterSpecification
Power Output35 watts per channel RMS
Frequency Response20Hz - 20kHz ±1dB
Total Harmonic Distortion<0.5% at rated output
Input SensitivityPhono: 2.5mV, Aux: 250mV
Signal-to-Noise RatioPhono: 65dB, Aux: 75dB
Tuner SectionAM/FM stereo with multiplex
Tubes12AX7, 12AU7, 6CA4, EL84/6BQ5
Power Requirements117V AC, 60Hz, 120 watts
Dimensions15" W × 5" H × 12" D
Weight22 lbs

Circuit Description

Detailed explanation of the Model 19's circuit topology and signal path.

  1. Preamplifier Stage: Dual 12AX7 tubes for phono and line-level amplification
  2. Tone Control: Bass and treble controls with passive networks
  3. Power Amplifier: Push-pull EL84/6BQ5 output tubes in ultra-linear configuration
  4. Power Supply: Tube rectifier (6CA4) with capacitor-input filter
  5. Tuner Section: Separate FM and AM RF/IF stages with multiplex decoder

WARNING! High voltages present - exercise extreme caution when servicing.

Alignment Procedures

Step-by-step alignment instructions for FM and AM sections.

  1. FM IF Alignment: Adjust IF transformers for maximum output at 10.7MHz
  2. FM Front End: Align RF stages for proper tracking across band
  3. AM Alignment: Adjust IF at 455kHz and antenna trimmer
  4. Stereo Multiplex: Adjust 19kHz pilot and 38kHz subcarrier
  5. Output Balance: Adjust for equal channel output and minimum distortion

CAUTION! Use proper alignment tools and follow sequence exactly.

Tube Complement

Voltage Measurements

Reference voltage measurements with line voltage at 117V AC.

Test PointDC VoltageAC Voltage
B+ Supply+385V--
EL84 Plate+315V--
EL84 Screen+305V--
12AX7 Plate+180V--
12AX7 Cathode+1.5V--
Heater Supply--6.3V

Schematic Diagrams

Complete schematic diagrams included for:

  1. Main Amplifier Circuit
  2. Preamplifier and Tone Control
  3. FM Tuner Section
  4. AM Tuner Section
  5. Power Supply
  6. Control Switches and Inputs

Note: Schematics show component values and test points.

Parts List

Complete component listing with original Marantz part numbers.

Part NumberDescriptionValue/Rating
MP-101Power TransformerPrimary 117V
MP-102Output Transformer8 ohm secondary
MP-201Electrolytic Capacitor40μF/450V
MP-301Carbon Resistor100K 1/2W
MP-401Tube Socket9-pin miniature

Mechanical Assembly

Disassembly and reassembly instructions with exploded views.

  1. Chassis Removal: Remove bottom plate and knobs
  2. Board Access: Remove mounting screws for circuit boards
  3. Transformer Replacement: Note orientation and mounting
  4. Front Panel: Carefully remove switches and indicators
  5. Reassembly: Reverse procedure, ensure proper grounding

Tip: Take photos during disassembly for reference.

Troubleshooting Guide

SymptomPossible CauseCorrective Action
No soundBlown fuse, dead tubesCheck fuse F1, test all tubes
Hum in audioFilter capacitors, groundingReplace electrolytics, check grounds
DistortionOutput tubes, biasTest/replace output tubes, check bias
Weak FM receptionRF tube, alignmentReplace V10, realign front end
No stereo lightMultiplex circuit, bulbCheck stereo decoder, replace bulb

Reset: Power cycle and check all connections.

Safety Precautions

Essential safety procedures for working with tube equipment.

WARNING! Lethal voltages present - always discharge capacitors before servicing. Use isolation transformer. Work with one hand when possible.

Service Notes

Additional service information and common modifications.

For technical support contact Marantz service department or authorized service centers.

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