Yamaha ax 400 u

Page 1

STEREO INTEGRATED AMPLIFIER

AX-400/AX-4OOU

IMPORTANT NOTICE

This manual has been provided for the use of authorized Yamaha Retaiiers 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 iniury, 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 or recognition of any applicable technical capabilities, or
establish a principle-agent relationship of any form.

The data provided is believed to be accurate and applicable in the unit(s) indicated on the covert The

research, engineering, and service departments of Yamaha are continually striving to improve Yamaha

products. Modifications are, therefore, inevitable and specifications are subiect to change without notice or

obligation to retrofit. Should any discrepancy appear to exist, please contact the distributor's Service

y Divisions

WARNING: Static discharges can destroy expensive components. Discharge any static electricity your
body may have accumulated by grounding yourself to the ground huss in the unit (heavy
gauge biack wires connect to this buss). 4

IMPORTANT: Turn the unit OFF during disassembly and parts replacement. Recheck all work before
you apply power to the unit.

I CONTENTS

TO SERVICE PERSONNEL . ...... . . . ....... 1 DISASSEMBLY PROCEDURES .............. 5

FRONT PANELS . . ............... . . . . 1 ADJUSTMENTS .................. . . . . . . 5
REARPANELS................. .2 PRINTEDCIRCUITBOARD... 6~9
SPECIFICATIONS. ....... . ....... ....3 WIRING...... ...........9
INTERNAL VIEW . ...................... 3 SCHEMATIC DIAGRAM .............. . . . . 10
BLOCKDIAGRAM .......... 4 PARTS LIST .................... ...11~17

YAMAHA

. NIPPON GAKKI Ell, LTDi HAMAMATSU. JAPAN

3.15K-142 @ Printed in Japan '86.11

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AX-400/AX-4OOU

I TO SERVICE PERSONNEL

1. Critical Components Information.
Components having special characteristics are marked
A and must be replaced with parts having specifica-
tions equal to those originally installed.

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

Meter impedance should be equivalent to 1500 ohm
shunted by 0.15uF.

Leakage current must not exceed 0.5mA.

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

I FRONT PANELS

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