Yamaha AX-496 Service manual

AX-496/396

P.O.Box 1, Hamamatsu, Japan

STEREO AMPLIFIER

AX-496/396

SERVICE MANUAL

AX-496/396

This manual has been provided for the use of authorized YAMAHA Retailers and their service personnel.
It has been assumed that basic service procedures inherent 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 any 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 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 part replacement. Recheck all work before you apply

power to the unit.

■ CONTENTS

SPECIFICATIONS.......................................................... 1

TO SERVICE PERSONNEL .......................................... 2

REMOTE CONTROL PANEL ........................................ 2

IMPEDANCE SELECTOR ............................................. 2

FRONT PANELS ............................................................ 3

REAR PANELS .............................................................. 3

INTERNAL VIEW ........................................................... 6

DISASSEMBLY PROCEDURES ................................... 6

IMPORTANT NOTICE

ADJUSTMENTS ............................................................. 7

BLOCK DIAGRAM ......................................................... 8

µ-COM DATA ................................................................. 9

PRINTED CIRCUIT BOARD .................................. 10~25

SCHEMATIC DIAGRAM ........................................ 26~29

PARTS LIST ........................................................... 30~47

REMOTE CONTROL TRANSMITTER ........................ 48

100702

AX-496/396

■ SPECIFICATIONS

■ Power Section

Minimum RMS Output Power

8Ω, 20Hz to 20kHz, 0.019% THD
AX-496 85W+85W
AX-396 60W+60W

Maximum Output Power (EIAJ)

1kHz, 10% THD
AX-496 8Ω/6Ω 130W / 150W
AX-396 6Ω 110W

Dynamic Power (IHF)

8/6/4/2Ω
AX-496 130/150/185/220W
AX-396 100/120/140/150W

DIN Standard Output Power

4Ω, 1kHz, 0.7% THD
AX-496 120W
AX-396 95W

IEC Output Power

8Ω, 1kHz, 0.019% THD
AX-496 100W
AX-396 75W

Power Band Width

8Ω, Half power, 0.04% THD 10Hz to 50kHz

Damping Factor

8Ω, 20Hz to 20kHz 240

Frequency Response

20Hz to 20kHz 0±0.5dB

Total Harmonic Distortion (20Hz to 20kHz)

CD/DVD to SP OUT (8Ω, Half power) 0.008%

Signal to Nise Ratio (IHF-A-Network)

CD/DVD (Input Shorted, CD/DVD DIRECT AMP ON) 110dB
PHONO (Input Shorted) 88dB

Residual Noise (IHF-A-Network)

CD/DVD DIRECT AMP ON 35µV

■ Control Section
Input Sensitivity / Impedance

CD/DVD etc. 150mV / 47kΩ
PHONO 2.5mV / 47kΩ

Output Level / Impedance

REC OUT 150mV / 1.6kΩ

Headphone Jack Rated Output / Impedance

0.25V / 680Ω

Channel Separation

CD/DVD (Input 5.1kΩ Terminated) 1kHz/10kHz 65 / 50dB

Tone Control Characteristics

BASS ±10dB (20Hz)
TREBLE ±10dB (20kHz)

Continuous Loudness Control

Attenuation -30dB (1kHz)

■ General
Power Supply

R, T models AC110/120/220/240V, 50/60Hz
A model AC240V, 50Hz
B, G models AC230V, 50Hz

Power Consumption

AX-496 Approx. 210W
AX-396 Approx. 150W

AC Outlets (Switched)

R, T, G models 100W Max x 3
A, B models 100W Max x 1

Dimensions (W x H x D) 435 x 151 x 391mm

Weight

AX-496 9.5 kg (21lbs)
AX-396 8.7 kg (19lbs 3oz)

Accessories

Color

* Specifications subject to change without notice.

(17-1/8" x 5-15/16" x 15-3/8")

Remote Control Transmitter

Batteries

Gold / Black / Titan

R ........ General model T ..... China model

A ........ Australia model B .... British model

G ........ European model

• DIMENSIONS

21.5

(7/8")

391 (15-3/8")

19.5
(3/4")

130 (5-1/8") 350 (13-3/4")21

151 (5-15/16")

435 (17-1/8")

Unit : mm (inch)

(13/16")

1

AX-496/396

■ TO SERVICE PERSONNEL

1. Critical Components Information.

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

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

● Meter impedance should be equivalent to 1500 ohm shunted

by 0.15µF.

● Leakage current must not exceed 0.5mA.

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

WALL

OUTLET

EQUIPMENT

UNDER TEST

INSULATING

TABLE

AC LEAKAGE

TESTER OR

EQUIVALENT

WARNING: CHEMICAL CONTENT NOTICE!

The solder used in the production of this product contains LEAD. In addition, other electrical/electronic and /or plastic
(where applicable) components may also contain traces of chemicals found by the California Health and Welfare Agency
(and possibly other entities) to cause cancer and/or birth defects or other reproductive harm.

DO NOT PLACE SOLDER, ELECTRICAL/ELECTRONIC OR PLASTIC COMPONENTS IN YOUR MOUTH FOR ANY REA­SON WHATSOEVER!

Avoid prolonged, unprotected contact between solder and your skin! When soldering, do not inhale solder fumes or expose
eyes to solder/flux vapor!

If you come in contact with solder or components located inside the enclosure of this product, wash your hands before
handling food.

■ REMOTE CONTROL PANEL

STANDBY/ON

DECK A/B

TAPE

DIR BDIR A

DISC SKIP

CD

TUNER

PHONO

A/B/C/D/EPRESET

CD/DVDMD TAPE

TUNERAUX

–+

■ IMPEDANCE SELECTOR

IMPEDANCE SELECTOR

VOLUME

–+

RAX9 V499920

WARNING:

Do not change the IMPEDANCE SELECTOR
switch setting while the power to this unit is
on, otherwise this unit may be damaged.

2

AX-496/396

■ FRONT PANELS

▼AX-496

▼AX-396

■ REAR PANELS (AX-496)

R model

3

T model

B model

AX-496/396

G model

■ REAR PANELS (AX-396)

R model

4

AX-496/396

A model

B model

G model

J model

5

1

1

2

3

3

4

4

5

5

6

7

7

7

■ INTERNAL VIEW

AX-496/396

7

1

9 0 A8

32546

■ DISASSEMBLY PROCEDURES

1 AX-496: MAIN P.C.B. (6) / AX-396: MAIN P.C.B. (7)
2 MAIN P.C.B. (2)
3 MAIN P.C.B. (1)
4 MAIN P.C.B. (3)
5 FUNCTION P.C.B. (4)
6 FUNCTION P.C.B. (5)
7 MAIN P.C.B. (9)
8 MAIN P.C.B. (8)
9 FUNCTION P.C.B. (7)
0 FUNCTION P.C.B. (6)
A FUNCTION P.C.B. (1)
B FUNCTION P.C.B. (2)

B

(Remove parts in the order as numbered.)

1. Removal of Top Cover

Remove 4 screws (1) and 4 screws (2) in Fig. 1.

2. Removal of Front Panel

a. Remove 6 screws (3) in Fig. 1.

3. Checking and Parts Replacement of MAIN P.C.B. (1)

a. Disconnect the power cord from the AC outlet.
b. Remove 3 screws (4) attaching the Speaker terminal

and Impedance Selector in Fig. 1.

c. Remove 2 screws (5) and remove 1 plastic rivet (6) in

Fig. 1, then remove the Sub Chassis.

d. Remove 4 screws (7) in Fig. 1, then remove the MAIN

P.C.B. (1) with Heat Sink and Chassis.

Fig. 1

6

AX-496/396

■ ADJUSTMENTS

Confirmation of Idling Current

Right after Power is switched ON, confirm the voltages

•

measures at R553 (L ch) and R561 (R ch) are between

0.1mV to 10mV.
If it exceeds 10mV, open (cut off) R552 (L ch), R560 (R

•

ch) and reconfirm the voltage.

R553 (L ch
R561 (R ch

0.1mV〜10mV

R553

)

)

R552 (L ch
R560 (R ch

R561

Cut

)

)

R552 R560

7

10dB

–10dB

PHONO

CD

SP A

SP B

PHONES

TUNER

AUX

TAPE1
PB

TAPE1
REC

MD
PB

MD
REC

CD DIRECT AMP

PHONO EQ AMP

CD DIRECT AMP

CD DIRECT AMP

MOTOR
DRIVER

ON

ON

OFF

OFF 31.8dB

M

Main VR

10dB

SMU

LOUDNESS
BALANCE
TONE CONTROL

AUDIO
MUTE

A

B

POWER AMP

RYSP

LB

15

–15

B

–B

LB

12S

+

+

+

+

+

+

AUDIO MUTE

SMU

Rec Select

Rec Select Data

Power ON

Power ON/OFF
RYPS

Remote Control

Input Select Data

Input Select

Main VR

Protection

RYSP

U-COM

RYPS

10dB

–10dB

PHONO

CD

SP A

SP B

PHONES

TUNER

AUX

TAPE1
PB

TAPE1
REC

TAPE2
PB

TAPE2
REC

CD DIRECT AMP

PHONO EQ AMP

CD DIRECT AMP

CD DIRECT AMP

MOTOR
DRIVER

ON

ON

ON

OFF

OFF

OFF 33.5dB

M

Main VR

10dB

SMU

RYPS

LOUDNESS
BALANCE
TONE CONTROL

PURE DIRECT

AUDIO
MUTE

A

B

POWER AMP

RYSP

LB

15

–15

B

–B

LB

12S

+

+

+

+

+

+

AUDIO MUTE

SMU

Rec Select

Rec Select Data

Power ON

Power ON/OFF
RYPS

Remote Control

Input Select Data

Input Select

Main VR

Protection

RYSP

U-COM

■ BLOCK DIAGRAM

▼ AX-496

AX-496/396

▼ AX-396

8

AX-496/396

■ µ-COM DATA

IC101 : M37478M4-409SP

No. Port I/O Form RE Function

1 P53 I I
2 P17 I/O O CEI Chip Enable (Input selector)
3 P16 I/O O CK Clock S-CLK
4 P15 I/O O DATA Data T x D
5 P14 I/O O
6 P13 I/O O TMO Tape Monitor
7 P12 I/O O VRUP Motor Volume (UP)
8 P11 I/O O VRDN Motor Volume (DOWN)

9 P10 I/O O RYPS Power Relay
10 P27 I I ENR Rotary Encoder (Right)
11 P26 I I ENL Rotary Encoder (Left)
12 P25 I I D34/5 AX-496, 396/596 Detect H: 496, 396 L: 596
13 P24 I I
14 P23 I I REC Rec Out Selector Detect IN3
15 P22 I I PRDC Protection (DC) IN2
16 P21 I I PRI Protection (Overload) IN1
17 P20 I I PRPS Protection (Power Supply) IN0
18 Vref I VREF
19 Xin I XIN
20 Xout O XOUT
21 Vss VSS
22 Vcc VCC
23 P50 I I PRINH Release the Protection
24 P61 I/O O
25 /RESET I /RESET
26 P30 I I PD Power Down Detect INT0
27 P31 I I REM Remote Control INT1
28 P32 I I D43 AX-493/393 Detect
29 P33 I I TPM Tape Monitor
30 P40 I/O O LEDTM LED (Tape Monitor)
31 P41 I/O O MUTE Mute
32 P42 I/O O RYSP Speaker Relay
33 P43 I/O O LSBY LED (Power)
34 P00 I/O I PS Power Key On Wakeup
35 P01 I/O I REM Remote Control (Wakeup) Key On Wakeup
36 P02 I/O O LEDP LED (Phono)
37 P03 I/O O LEDTM LED (Tuner)
38 P04 I/O O LEDC LED (CD)
39 P05 I/O O LEDM LED (Tape)
40 P06 I/O O LEDTP LED (MD)
41 P07 I/O O LEDA LED (AUX)
42 P52 I I

9

ABCDEFGH I J

1

■ PRINTED CIRCUIT BOARD (Foil side)

P.C.B. MAIN (3)

2

3

P.C.B. MAIN (1)

MU

S12

GND

GND

RYSP

RYPS

PRPS

PRI

AX-496

PRD

VRP

VRG

AX-496/396

To FUNCTION (1)

SPEAKERS

4

To FUNCTION (6)

E
R
E
L
E
15

-15

5

6

IMPEDANCE
SELECTOR

RE

HL
E
HR
RYSP
A

7

B

To FUNCTION (7)

YE

10

RE

BE

BE

OR

OR

To MAIN (6)

11

ABCDEFGH I J

POWER

TRANSFORMER

To MAIN (2)To MAIN (4)

GYBR BR WH YE RE OR RE

AX-496/396

1

■ PRINTED CIRCUIT BOARD (Foil side)

P.C.B. MAIN (2)

AX-496

P.C.B. MAIN (5) (R, T models)

BE

To MAIN (9)

P.C.B. MAIN (6)

To MAIN (1)

RE OR BE YE BE REOR

To MAIN (8)
To MAIN (5)

2

AC OUTLETS

3

4

(B, G models)

(R, T models)

GY

BR

WH

E

+12

RYPS

To MAIN (1)

POWER

TRANSFORMER

5

P.C.B. MAIN (4) (R, T models)

POWER

To MAIN (5)

WH RE YE

6

RE BR OR

7

P.C.B. MAIN (8) (B, G models)

To MAIN (2)

GY BR

POWER

TRANSFORMER

P.C.B. MAIN (9)

To MAIN P.C.B. (2)

12

13

ABCDEFGH I J

1

■ PRINTED CIRCUIT BOARD (Foil side)

P.C.B. FUNCTION (6)

To MAIN (1)

2

3

8

1

-15

+15ELER

AX-496/396

AX-496

E

TLO
E
TRO

-15
TLI
15
TRI
E
L
E
R

To FUNCTION (1)

To MAIN (1)

To FUNCTION (4)

VRG
VRP
PRO
PRI
PRPS
RYPS
RYSP
DG
DG
S12
MU

CE

DATACL-15LER15

2221

CDDLECDDR

CDM

P.C.B. FUNCTION (1)

142

BASS TREBLE BALANCE LOUDNESS

4

To FUNCTION (8)

LSBYPHTUCDMDTAAU5VREMDGPS

To FUNCTION (6)

5

6

P.C.B. FUNCTION (3)

TLO
E
TRO

-15
TLI
15
TRI
E
L
E
R

GND
CD-D
TPMLED
P-D/5V

REC OUT

To FUNCTION (11)

CD/DVD DIRECT AMP PURE DIRECT

7

INPUT

VOLUME

P.C.B. FUNCTION (2)

1514