Pioneer SPEC-4 Service Manual

Lists semiconductor components used in the amplifier.

Details power output, distortion, frequency response, and damping factor.

Covers power requirements, consumption, dimensions, and weight.

Lists included items like connection cords and operating instructions.

Explains the power switch functionality and delay before sound.

Details the function and usage of the peak output power meters.

Procedure for adjusting the zero point of the peak level meters.

Instructions for adjusting input level controls for optimal output.

Instructions for using the hexagonal wrench to tighten knobs.

Diagram showing how to connect input sources and speaker systems.

Details the function and power capacity of the unswitched AC outlet.

Overview of the main functional blocks of the amplifier system.

Detailed explanation of the power amplifier circuitry and its design.

Describes the operation and components of the peak output meter amplifier.

Explains the protection circuit for transistors and speakers, and muting function.

Details the muting function sequence during power ON/OFF.

How detector circuits command the relay drive circuit.

Explains the overload detection mechanism and its operation.

Describes the center point potential detection for DC offset protection.

Details the dual power transformers, bridge rectifiers, and capacitors.

Explains staggered powering of transformers to reduce inrush current.

Details electrolytic capacitor ground, cord construction, and input attenuator.

Instructions for removing the top cover of the amplifier.

Procedure for detaching the front panel, including knobs.

Steps for removing the bottom plate of the amplifier unit.

Diagram showing the location and part numbers of front panel components.

Illustration of internal parts visible after removing the front panel.

Diagram illustrating the arrangement of major internal components from the top.

Illustration of internal components visible from the bottom of the unit.

Diagram showing the location and part numbers of rear panel connectors and outlets.

Procedures for DC balance, idle current, and power limiter adjustments.

Instructions for setting the DC balance at the speaker output terminals.

Procedure for adjusting the idle current for proper operation.

Steps to adjust the power limiter for optimal output and distortion.

Procedure for adjusting the output meter to indicate 0dB.

Defines symbols used for screws, washers, and nuts in exploded views.

Illustrates how to interpret part numbers and dimensions for screws.

Exploded view showing the arrangement and part numbers of external components.

Exploded view of the panel stay block and its associated parts.

Exploded view of the center chassis block with transformers and power supplies.

Exploded view of the rear panel block, including connectors and outlets.

Exploded view of the power amplifier block with transistors and heatsinks.

Provides schematic diagrams and lists of miscellaneous parts like switches and lamps.

List of switches and relays used in the unit with their part numbers.

List of lamps and fuses with their specifications and part numbers.

List of power transformers used in the unit with their part numbers.

List of variable resistors (potentiometers) with specifications and part numbers.

List of capacitors with types, values, and part numbers.

List of transistors and diodes with part numbers and types.

List of other miscellaneous parts like assemblies and connectors.

Detailed schematic of the entire amplifier circuit.

Illustrations showing the external appearance of various transistors and ICs.

Diagram showing the foil side layout of the meter amplifier assembly.

Detailed list of resistors and capacitors for the meter amplifier assembly.

List of semiconductors used in the meter amplifier assembly.

List of diodes used in the meter amplifier assembly.

List of other components like heat sinks for the meter amplifier.

List of parts changed during factory modifications.

Diagram showing the foil side layout of the power amplifier assembly.

Detailed list of resistors and potentiometers for the power amplifier assembly.

List of semiconductors used in the power amplifier assembly.

List of other components like AF choke coil and heat sinks for the power amplifier.

List of parts changed for factory modifications in the power amplifier.

Diagram showing the foil side layout of the fuse assembly.

List of capacitors, semiconductors, and fuse clips for the fuse assembly.

List of capacitors used in the fuse assembly.

List of semiconductors used in the fuse assembly.

List of fuse clips for the fuse assembly.

Diagram showing the foil side layout of the AWR-139 power supply assembly.

List of resistors, semiconductors, and capacitors for the AWR-139 power supply.

List of resistors used in the AWR-139 power supply assembly.

List of semiconductors used in the AWR-139 power supply assembly.

List of capacitors used in the AWR-139 power supply assembly.

Diagram showing the foil side layout of the AWR-140 power supply assembly.

List of resistors, semiconductors, and capacitors for the AWR-140 power supply.

List of resistors used in the AWR-140 power supply assembly.

List of semiconductors used in the AWR-140 power supply assembly.

List of capacitors used in the AWR-140 power supply assembly.

Exploded view showing all components and materials used for packing the unit.