Yamaha a 40

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STEREO INTEGRATED AMPLIFIER

A-40/A-45

SERVICE MANUAL

IMPORTANT NOTICE

This manual has been provided for the use of authorized Vamaha Retailers and their service personnel.
It has been asSUmed that basic service procedures inheranI 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 saiety 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 Vamaha Retailer or the
appointed service representative.

IMPORTANT: The presentation or sale of this manual to any individual or firm does not constitute
authorization, certification orrecognition of any applicable technical capabilities, 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 all work before
you apply power to the unit.

.CONTENTS

TO SERVICE PERSONNEL ........
INTERNAL VIEW ..............

A-40 PANELS 8t REMOTE CONTROL

TRANSMITTER ...........

A-45 PANELS 8t REMOTE CONTROL

TRANSMITTER ...........
A-40 SPECIFICATIONS ..........
A~45 SPECIFICATIONS ..........
A-40 BLOCK DIAGRAM .........
A45 BLOCK DIAGRAM .........
DISASSEMBLY PROCEDURES .....

......... 1 ADJUSTMENTS........................8
......... 1 ICDATA..........................9~1o

INTERCONNECT WIRING DIAGRAM ........ 11
......... 2 A-40PRINTEDCIRCUITBOARD........12~16

A-45 PRINTED CIRCUIT BOARD ........ 17~21
......... 3 A40 SCHEMATIC DIAGRAM.............. 22
......... 4 A-45 SCHEMATICDIAGRAM.............. 23
......... 5 A-40PARTSLIST.....,.............24~30
......... 6 A-4sPARTSLIST...................31~37
--------- 7 REMOTECONTROLTRANSMITTER 38
......... 8

YAMAHA

YAMAHA CORPORATION
OBox1 Hamamatsu. Japan

1.7K-294 IEQOP Printed in Japan 89.2

sv-v/ov-v

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A-40/A-4

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I TO SERVICE PERSONNEL

I.

Critical Components Information.

Components having special characteristics are marked A
and must be replaced with parts having specifications equal
to those originally installed

Leakage Current Measurement (For 120V Model Only).
When service has been completed, it is imperative that you
verily that all exposed conductive surfaces are properly
insulated from supply circuits.

Meter impedance should be equivalent to 1500 ohm shunted
by 01 EMF

Leakage current must not exceed 0.5mA.

Be sure to test for leakage with the AC plug in both polarities.

I INTERNAL VIEW

EQUIPMENT AC LEAKAGE TESTER
UNDER TEST OFI EQUIVALENT
-
WALL {:1 J:-
OUTLET INSULATING TABLE -

O POLARIZATION (U, C models only)

This amplifier product is equipped with a polarized alter-
nating current line plug (a plug having one blade wider than
the other). This plug will fit into the power outlet only one
way. This is a safety feature.

OPOWER TRANSFORMER
QSub Circuit Board (3)
OPOWER TRANSISTOR
OPOWER TRANSISTOR
9 POWER SWITCH

GMAIN CIRCUIT BOARD (4)
ODIODE BRIDGE: 4D4B41
®DIODE BRIDGE: 234341
OMAIN CIRCUIT BOARD (1)
0 4bit p-COM: LCG505C-3525