Pioneer A-656 - User Manual

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PARTS:

MASTER

STEREO

AMPLIFIER

evs

ass

Oar

“A-656"

not

available

U.S.

Operating

Instructions

The

illustration

shows

model

A-757.

Thank

you

for

buying

this

Pioneer

product.

Please

read

through

these

operating

instructions

you

will

know

how

operate

your

unit

properly,

After

you

have

finished

reading

the

instructions,

keep

the

manual

safe

place

for

future

reference.

some

countries

regions,

the

shape

the

power

plug

and

power

outlet

may

sometimes

differ

from

that

shown

the

drawings.

However,

the

method

connecting

and

operating

the

unit

the

same,

WARNING

PREVENT

FIRE

SHOCK

HAZARD,

NOT

EXPOSE

THIS

APPLIANCE

RAIN

MOISTURE.

IMPORTANT

NOTICE

[FOR

U.S.

and

Canadian

models]

The

serial

number

for

this

equipment

located

the

rear

panel.

Please

write

this

serial

number

your

enclosed

warranty

card

and

keep

secure

area.

This

for

your

security.

[For

Canadian

model]

CAUTION:

PREVENT

ELECTRIC

SHOCK

NOT

USE

THIS

(POLARIZED)

PLUG

WITH

EXTENSION

CORD,

RECEPTACLE

OTHER

OUTLET

UNLESS

THE

BLADES

CAN

FULLY

INSERTED

PREVENT

BLADE

EXPOSURE.

ATTENTION

POUR

PREVENIR

LES

CHOCS

ELECTRIQUES

PAS

UTILISER

CETTE

FICHE

POLARISEE

AVEC

PROLONGATEUR

UNE

PRISE

COURANT

UNE

AUTRE

SORTIE

COURANT,

SAUF

LES

LAMES

PEUVENT

ETRE

INSEREES

FOND

SANS

LAISSER

AUCUNE

PARTIE

DECOUVERT.

LINE

VOLTAGE

SELECTOR

SWITCH

Only

multi-voltage

models

are

provided

with

this

switch.

U.S.,

Canadian,

European,

U.K.,

and

Australian

models

are

not

provided

with

this

switch.

Mains

voltages

Saudi

Arabia

are

127V

and

220V

only.

Never

use

this

model

with

110V

setting

Saudi

Arabia.

The

line

voltage

selector

switch

the

rear

panel.

Before

your

model

shipped

from

the

factory,

this

switch

set

the

power

requirements

the

destination.

Check

that

set

properly

before

plugging

the

power

cord

into

the

wall

socket.

the

voltage

not

properly

set

you

move

area

where

the

voltage

requirements

differ,

adjust

the

selector

switch

follows.

Use

medium-size

screwdriver.

Insert

the

screwdriver

into

the

groove

the

voltage

selector,

and

adjust

so that

the

tip

the

arrow

points

the

voltage

value

your

area.

VOLTAGE

SELECTOR

120-127

HOV

2s0v

204

Medium-size

screwdriver

PIONEER’

The

future

sound

and

vision.

iif

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Summary

Operating Instructions Overview

Important Safety and Voltage Information

Covers fire/shock hazards, moisture, and voltage selector adjustments for regional use.

General Safety Instructions

Appliance Safety Precautions

Guidelines for safe placement, ventilation, heat, power, and cleaning.

Electrical and Grounding Safety

Details on polarized plugs, cord protection, and outdoor antenna grounding.

Connection Diagrams

Component and Speaker Wiring

Visual guide for connecting audio sources, tape decks, and speaker systems.

Troubleshooting and Safety

Problem Resolution Guide

Table of common issues, probable causes, and remedies for operation problems.

Power Cord Handling Caution

Important safety advice for managing and maintaining the power cord.

Summary

Operating Instructions Overview

Important Safety and Voltage Information

Covers fire/shock hazards, moisture, and voltage selector adjustments for regional use.

General Safety Instructions

Appliance Safety Precautions

Guidelines for safe placement, ventilation, heat, power, and cleaning.

Electrical and Grounding Safety

Details on polarized plugs, cord protection, and outdoor antenna grounding.

Connection Diagrams

Component and Speaker Wiring

Visual guide for connecting audio sources, tape decks, and speaker systems.

Troubleshooting and Safety

Problem Resolution Guide

Table of common issues, probable causes, and remedies for operation problems.

Power Cord Handling Caution

Important safety advice for managing and maintaining the power cord.

This document provides comprehensive operating instructions for the Pioneer Stereo Amplifiers A-757 and A-656, designed to ensure proper usage and longevity of the units. The manual emphasizes safety precautions, connection procedures, operational guidelines, troubleshooting tips, and maintenance advice.

Function Description

The Pioneer Stereo Amplifiers A-757 and A-656 are high-fidelity audio components designed to amplify audio signals from various sources and deliver them to speaker systems. These amplifiers serve as the central hub for an audio setup, allowing users to connect and manage multiple input devices such as CD players, tuners, turntables, tape decks, video disc players, and VCRs. The primary function is to process and amplify these audio signals, providing a rich and clear sound experience.

The A-757 model, in particular, is highlighted with a robust drive capacity of 150W + 150W/4 Ω (DIN), making it suitable for high-power and low-impedance speaker systems. The A-656 model offers a drive capacity of 120W + 120W/4 Ω (DIN). Both models incorporate a "DIRECT" circuit, which ensures high-fidelity playback by maintaining consistent frequency characteristics and maximizing clarity, bypassing various frequency-adjusting circuits for a purer sound.

A key feature is the built-in phono equalizer, which accommodates both Moving Magnet (MM) and Moving Coil (MC) cartridges, allowing for direct connection of turntables. The A-757 model also includes a PHONO EQ switch/indicator to prevent noise when a phono input is not in use.

The amplifiers are equipped with a "REC SELECTOR" switch, simplifying tape editing and recording processes. This switch allows users to select the recording source independently of the playback source, facilitating flexible recording options, including tape-to-tape copying.

For enhanced sound quality, the amplifiers feature "clean ground technology," which prevents noise from the power line from interfering with the signal ground line, contributing to clean sound reproduction. They also utilize Non-Switching Circuit Type III (A-757) or Type II (A-656) to minimize distortion and achieve high-quality sound.

The design incorporates advanced structural elements such as a Casted Power Transformer (A-757 only), Honeycomb Frame Chassis, and Honeycomb Heat Sink, all contributing to the unit's stability, durability, and efficient heat dissipation, which are crucial for consistent performance.

Usage Features

The amplifiers offer a user-friendly interface with various controls and switches for managing audio playback and recording.

Input Selection: The "INPUT SELECTOR" switch allows users to choose among different audio sources like LINE, TUNER, PHONO, CD, DAT/TAPE 1, and TAPE 2. This ensures that the correct input is routed for amplification.

Speaker Management: The "SPEAKERS selector switch" enables users to direct audio to different speaker systems (A, B, or A+B) or to headphones, providing flexibility in listening environments. When using headphones, the switch should be set to "OFF" to mute the speakers.

Volume and Tone Control: A large "VOLUME CONTROL" knob adjusts the overall sound level. "BASS" and "TREBLE" tone controls allow for adjustment of low and high frequencies, respectively, to tailor the sound to personal preferences. These tone controls, along with the "BALANCE" control (for adjusting left/right channel balance) and "LOUDNESS" switch (for boosting low and high frequencies at low volumes), are bypassed when the "DIRECT" switch is engaged, ensuring a pure signal path.

Recording and Copying: The "REC SELECTOR" switch is central to recording operations. It allows users to select a specific source (TUNER, CD, SOURCE) for recording onto a connected tape deck. It also supports tape-to-tape copying (TAPE 1→2 or TAPE 2→1), making it easy to duplicate recordings. The manual provides clear instructions for monitoring while recording, especially with 3-head tape decks.

Adapter Functionality: The "ADPT 1/TAPE 3" and "ADPT 2" terminals (A-757 only) allow for the connection of external audio processors like graphic equalizers. Shorting bars are provided for these terminals and must be removed when an adapter is connected, and reinserted when not in use to maintain signal integrity.

Power Management: The "POWER switch/indicator" turns the unit on and off. The amplifiers also feature "AC OUTLETS" (SWITCHED and UNSWITCHED) on the rear panel, allowing other audio components to draw power directly from the amplifier. The SWITCHED outlets are controlled by the amplifier's power switch, while UNSWITCHED outlets provide continuous power. Users are cautioned against connecting high-power appliances to these outlets to prevent overheating or fire risks.

Safety and Setup: The manual emphasizes initial setup steps, including setting the volume to minimum, turning on the power, selecting speaker outputs, and adjusting balance. It also provides specific instructions for connecting speaker cords, ensuring proper polarity and secure connections to prevent damage.

Troubleshooting: A dedicated troubleshooting section helps users diagnose common issues such as no power, no sound, sound from only one speaker, or recording problems. It offers probable causes and remedies, encouraging users to check connections, switch settings, and other components before seeking professional service.

Maintenance Features

The manual provides essential guidelines for maintaining the external surfaces of the amplifier to ensure its appearance and longevity.

Cleaning:

Regular Dusting: For routine cleaning, users should wipe off dust and dirt using a polishing cloth or a soft, dry cloth.
Deep Cleaning: For very dirty surfaces, a soft cloth dipped in a neutral cleanser diluted five or six times with water should be used. The cloth should be well wrung out to avoid excess moisture. After cleaning with the diluted cleanser, the surface should be wiped again with a dry cloth.
Avoid Harsh Chemicals: Users are explicitly warned against using furniture wax, benzine, insecticides, thinners, or any other volatile liquids on or near the unit. These substances can corrode the cabinet and damage the finish.

Power Cord Care:

Handle by Plug: Always handle the power cord by the plug, not by pulling on the cord itself.
Avoid Moisture: Never touch the power cord with wet hands, as this poses a risk of short circuit or electric shock.
Prevent Damage: Do not place the unit, furniture, or any heavy objects on the power cord. Avoid pinching, knotting, or tying the cord with other cords.
Routing: Power cords should be routed in a way that prevents them from being stepped on.
Inspection: Regular inspection of the power cord for any damage is recommended. If damage is found, users should contact a Pioneer authorized service center or dealer for replacement to prevent fire or electrical shock hazards.

General Care:

Stable Placement: The unit should always be placed on a level surface to ensure stability. If the unit is wobbly, supplied cushion spacers can be attached to one or more feet to stabilize it.
Ventilation: The amplifier should be situated in a location that does not obstruct its ventilation openings. Avoid placing it on soft surfaces like beds or sofas, or in enclosed spaces like bookcases or cabinets, which could impede airflow and lead to overheating.
Heat Sources: Keep the amplifier away from heat sources such as radiators, heat registers, stoves, or other heat-producing appliances to prevent overheating.
Liquid and Object Entry: Care should be taken to prevent objects from falling into or liquids from spilling onto the unit through its openings, as this can cause damage.

By adhering to these maintenance instructions, users can help preserve the aesthetic and functional integrity of their Pioneer Stereo Amplifiers.