Yamaha AX-300 Service Manual

NATURAL SOUND STEREO AMPLIFIER
SERVICE MANUAL
Ш FRONT PANEL
High Dynamic Power
YAMAHA
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TREBLE INPUT SELECTOR
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( IMPORTANT NOTICE й
This manual has been provided for the use of authorized Yamaha Retailers and their service personnel.
It has been assumed that basic service procedures inherant to the industry, and more specifically Yamaha
Products, are already known and understood by the users, and have therefore not been restated.
WARNING: Failure to follow appropriate service and safety procedures when servicing this product
may result in personal injury, destruction of expensive components and failure of the
product to perform as specified. For these reasons, we advise all Yamaha product owners
that all service required should be performed by an authorized Yamaha Retailer or the
appointed service representative.
IMPORTANT:
The
presentation
or
sale
of
this
manual
to
any
individual
or
firm
does
not
constitute
authorization,
certification,
recognition
of
any
applicable
technical
capabilitites,
or
establish
a
principle~agent
relationship
of
any
form.
The
data
provided
is
believed
to
be
accurate
and
applicable
to
the
unit(s)
indicated
on
the
cover.
The
research,
engineering,
and
service
departments
of
Yamaha
are
continually
striving
to
improve
Yamaha
products.
Modifications
are,
therefore,
inevitable
and
specifications
are
subject
to
change
without
notice
or
obligation
to
retrofit.
Should
any
discrepancy
appear
to
exist,
please
contact
the
distributor’s
Service
Division.
WARNING:
Static
discharges
can
destroy
expensive
components.
Discharge
any
static
electricity
your
body
may
have
accumulated
by
grounding
yourself
to
the
ground
buss
in
the
unit
(heavy
gauge
black
wires
connect
to
this
buss).
IMPORTANT:
Turn
the
unit
OFF
during
disassembly
and
parts
replacement.
Recheck
ай
work
before
you apply
power to
the
unit.
Ш CONTENTS
TO SERVICE PERSONNEL ................
SPECIFICATIONS .......................
REAR PANELS ........................
INTERNAL МІЕЎ.......................
DISASSEMBLY PROCEDURES ..............
BLOCK DIAGRAM ......................
WIRING 2; кои RUF eR RS
ADJUSTMENTS ........................ B
ADJUSTMENT
POINTS
...................5
IC BLOCK паре о Мары ku O
PRINTED
CIRCUIT
BOARD
..............6,7
SCHEMATIC
DIAGRAM
..................
8
PARTS LIST .......................9~14
BPD WOW N а m
100086
NIPPON
GAKKI
CO.,
LTD.
HAMAMATSU,
JAPAN
2.3K-703 Ф 6) Printed іп Тарап 86.11
00Е-ХУ

Yamaha AX-300 Specifications

General

Input Sensitivity	150 mV (line)
Signal-to-Noise Ratio	100 dB (line)
Channel separation	60 dB (1 kHz)
Total Harmonic Distortion (THD)	0.015%
Frequency Response	10Hz-100kHz (+0dB, -3dB)
Damping factor	80
Speaker load impedance	4 to 16 ohms

Summary

To Service Personnel

Critical Components Information

Leakage Current Measurement

Procedure to verify insulation of exposed surfaces from supply circuits for safety.

Specifications

Disassembly Procedures

Removal of Top Cover

Step-by-step instructions for removing the unit's top cover.

Removal of Front Panel

Step-by-step instructions for removing the unit's front panel.

Removal of Bottom Cover

Step-by-step instructions for removing the unit's bottom cover.

Block Diagram

Wiring

Adjustments

Idling Current Adjustment

Procedure to adjust idling current for power and drive transistors.

Adjustment Points

Printed Circuit Board Layouts

Schematic Diagrams

EQ Amp Schematic

Tone Amp and Main Amp Schematics

DC Detector and Protection Schematics

Transistor and IC Pin Connection Diagrams

Parts List

Electrical Parts

List of electrical components with part numbers, descriptions, and remarks.

Transistors, Diodes, Switches, and Fuses

List of transistors, diodes, switches, and fuses with part details.

Mechanism Parts

Carbon Resistor Parts