Kenwood KA 5700 Service Manual

The Kenwood KA 5700 is a high-quality stereo integrated amplifier featuring 60 watts per channel RMS, phono inputs for MM/MC cartridges, tape monitoring, loudness control, tone defeat, and comprehensive audio controls. This service manual provides detailed technical information for service technicians, including schematics, alignment procedures, parts lists, and troubleshooting guides. Below are key sections covering specifications, block diagrams, circuit descriptions, adjustment procedures, and maintenance information.

1. Specifications 2. Block Diagram 3. Circuit Description 4. Disassembly Instructions 5. Adjustment Procedures 6. Parts List 7. Schematic Diagrams 8. PCB Layouts 9. Troubleshooting Guide 10. Safety Precautions

Specifications

Technical specifications and performance characteristics of the Kenwood KA 5700 integrated amplifier.

ParameterSpecification
Power Output60W + 60W (RMS, 8Ω, 20Hz-20kHz)
Total Harmonic Distortion0.02% (at rated output)
Frequency Response5Hz-100kHz (+0, -3dB)
Input SensitivityPhono: 2.5mV, AUX: 150mV
Signal-to-Noise RatioPhono: 80dB, AUX: 100dB
Tone ControlsBass: ±10dB at 100Hz, Treble: ±10dB at 10kHz
Power SupplyAC 120V/220V/240V, 50/60Hz
Dimensions430(W) x 145(H) x 350(D) mm
Weight9.5 kg
Speaker Impedance4-16 ohms

Block Diagram

System overview showing signal flow and major functional blocks.

  1. Input Selector: Phono, AUX, Tuner, Tape 1, Tape 2
  2. Phono Equalizer: RIAA correction for magnetic cartridges
  3. Preamplifier Stage: Voltage amplification and tone control
  4. Power Amplifier: Complementary symmetry output stage
  5. Power Supply: Rectification and regulation circuits
  6. Protection Circuit: DC detection and relay control

NOTE: Refer to schematic diagrams for detailed component-level information.

Circuit Description

Detailed explanation of major circuit sections and their operation.

  1. Power Supply: Transformer, bridge rectifier, and filter capacitors providing ±45V DC
  2. Phono Stage: Low-noise transistor array with RIAA equalization
  3. Tone Control: Baxandall-type bass and treble controls with defeat switch
  4. Power Amplifier: Complementary Darlington output transistors with current limiting
  5. Protection Circuit: Monitors DC offset and controls speaker relay

CAUTION! High voltages present - discharge capacitors before servicing.

Disassembly Instructions

Adjustment Procedures

Factory alignment and calibration procedures for optimal performance.

Required Equipment: Audio generator, oscilloscope, distortion analyzer, digital multimeter

  1. DC Offset Adjustment: Adjust VR501/VR502 for 0mV ±5mV at speaker terminals
  2. Bias Current: Adjust VR503/VR504 for 20mA across emitter resistors
  3. Phono Equalization: Verify RIAA response with test records
  4. Input Level Matching: Adjust input sensitivity for uniform volume levels

Parts List

Complete component listing with manufacturer part numbers and substitutions.

ReferenceDescriptionPart NumberSubstitution
Q101-Q104Transistor 2SC22402SC2240BLKSC1845
Q501-Q504Output Transistor 2SC25812SC2581MJ21194
Q505-Q508Output Transistor 2SA11062SA1106MJ21193
D501-D504Diode 1S24731S24731N4148
C601,C602Capacitor 10000μF/63VECA-2AH103Similar spec

Schematic Diagrams

Complete circuit schematics for all amplifier sections.

  1. Main Amplifier Circuit: Power amplifier and driver stages
  2. Preamplifier Section: Phono equalizer and tone controls
  3. Power Supply: Transformer, rectification, and filtering
  4. Protection Circuit: DC detection and relay control
  5. Input Selector: Source switching and level control

Tip: Use high-resolution prints for component identification.

PCB Layouts

Printed circuit board patterns and component placement guides.

  1. Main Amplifier Board: Component side and solder side views
  2. Power Supply Board: Component placement and trace routing
  3. Front Panel Board: Switch and control wiring
  4. Protection Circuit Board: Relay and sensing components

WARNING! Observe polarity markings for electrolytic capacitors.

Troubleshooting Guide

SymptomPossible CauseCorrective Action
No sound from both channelsPower supply failureCheck fuse, transformer, rectifier diodes
Distortion in one channelOutput transistor failureTest output transistors and driver stages
Hum in phono inputGrounding issueCheck phono ground and shield connections
Protection relay not engagingDC offset or protection circuit faultMeasure DC offset at output terminals
Intermittent operationCold solder jointsInspect and resolder all connections

Service Notes: Always check bias current after replacing output transistors.

Safety Precautions

Essential safety information for service technicians and users.

WARNING! Lethal voltages present - disconnect from mains before servicing. Use isolation transformer when testing live circuits. Ensure proper grounding of test equipment. Replace safety components only with identical specifications.

Service Support: For technical assistance contact Kenwood service department or authorized service centers.

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