Sony SAWM-250 Service manual

SA-WM250

SERVICE MANUAL

Ver 1.0 2004.03

SPECIFICATIONS

AUDIO POWER SPECIFICATIONS

POWER OUTPUT AND TOTAL HARMONIC
DISTORTION:
With 6 ohm loads, from 28 – 200 Hz; rated 100 watts,
minimum RMS power, with no more than 0.8 % total
harmonic distortion from 250 milliwatts to rated
output.

System

Type Active Subwoofer (magnetically shielded design)
Speaker unit Woofer: 20 cm dia. (8 in.), cone type
RMS output 100 W (6 Ohms, 40 Hz, 10% THD)
Frequency range 28 Hz – 200 Hz
High frequency cut-off frequency

50 Hz – 200 Hz

Phase selector NORMAL, REVERSE

US Model

Canadian Model

AEP Model

UK Model

E Model

Inputs

Input jacks INPUT: input pin jack

SPEAKER IN: input terminals

Output jacks SPEAKER OUT: output terminals

General

Power requirements Taiwan models: 110 V AC, 50 Hz

USA and Canada models: 120 V AC, 60 Hz
Other models: 230 V AC, 50/60 Hz

Power consumption 100 W
Dimensions Approx. 290 × 355 × 387 mm

(11 3/8 × 14 × 15 1/4 in.) (w/h/d)

Mass 11.5 kg (25 lb 6 oz)
Supplied accessories Foot pads (4)

Audio connecting cord (1 phono – 1 phono),
2 m (6 ft 6 1/2 in.) (1)
Speaker cords, 2.5 m (8 ft 2 1/2 in.) (2)

Design and specifications are subject to change without notice.

9-877-696-01

2004C04-1

© 2004.03

ACTIVE SUBWOOFER

Sony Corporation

Home Audio Company
Published by Sony Engineering Corporation

1

r

SA-WM250

SAFETY CHECK-OUT

After correcting the original service problem, perform the follow­ing safety check before releasing the set to the customer:
Check the antenna terminals, metal trim, “metallized” knobs, screws,
and all other exposed metal parts for AC leakage.
Check leakage as described below.

LEAKAGE TEST

The AC leakage from any exposed metal part to earth ground and
from all exposed metal parts to any exposed metal part having a
return to chassis, must not exceed 0.5 mA (500 microampers.).
Leakage current can be measured by any one of three methods.

1. A commercial leakage tester, such as the Simpson 229 or RCA
WT-540A. Follow the manufacturers’ instructions to use these
instruments.

2. A battery-operated AC milliammeter. The Data Precision 245
digital multimeter is suitable for this job.

3. Measuring the voltage drop across a resistor by means of a
VOM or battery-operated AC voltmeter. The “limit” indica­tion is 0.75 V, so analog meters must have an accurate low­voltage scale. The Simpson 250 and Sanwa SH-63Trd are ex­amples of a passive VOM that is suitable. Nearly all battery
operated digital multimeters that have a 2 V AC range are suit­able. (See Fig. A)

To Exposed Metal
Parts on Set

TABLE OF CONTENTS

1. GENERAL

Location of Controls ................................................................ 3

2. DIAGRAMS

2-1. Note for Printed Wiring Boards and

Schematic Diagrams ............................................................ 3

2-2. Circuit Boards Location ...................................................... 3

2-3. Printed Wiring Boards – Main Section – ............................ 4

2-4. Printed Wiring Board – Input Control Section – ................. 5

2-5. Printed Wiring Boards – Power Section –........................... 6

2-6. Schematic Diagram – Main Section – ................................. 7

2-7. IC Block Diagram ............................................................... 8

3. EXPLODED VIEWS

3-1. Main Section ....................................................................... 9

4. ELECTRICAL PARTS LIST......................................... 10

0.15 µF

1.5 k

Earth Ground

(Fig. A)

UNLEADED SOLDER

AC

Ω

voltmete
(0.75 V)

•

Boards requiring use of unleaded solder are printed with the lead­free mark (LF) indicating the solder contains no lead.
(Caution: Some printed circuit boards may not come printed with
the lead free mark due to their particular size.)

: LEAD FREE MARK

Unleaded solder has the following characteristics.

• Unleaded solder melts at a temperature about 40°C higher than

ordinary solder.
Ordinary soldering irons can be used but the iron tip has to be
applied to the solder joint for a slightly longer time.
Soldering irons using a temperature regulator should be set to
about 350°C.
Caution: The printed pattern (copper foil) may peel away if
the heated tip is applied for too long, so be careful!

• Strong viscosity
Unleaded solder is more viscous (sticky, less prone to flow)
than ordinary solder so use caution not to let solder bridges
occur such as on IC pins, etc.

• Usable with ordinary solder
It is best to use only unleaded solder but unleaded solder may
also be added to ordinary solder.

SAFETY-RELATED COMPONENT WARNING!!

COMPONENTS IDENTIFIED BY MARK 0 OR DOTTED LINE
WITH MARK 0 ON THE SCHEMATIC DIAGRAMS AND IN
THE PARTS LIST ARE CRITICAL TO SAFE OPERATION.
REPLACE THESE COMPONENTS WITH SONY PARTS WHOSE
PA RT NUMBERS APPEAR AS SHOWN IN THIS MANUAL OR
IN SUPPLEMENTS PUBLISHED BY SONY.

2

ATTENTION AU COMPOSANT AYANT RAPPORT

À LA SÉCURITÉ!!

LES COMPOSANTS IDENTIFIÉS PAR UNE MARQUE 0 SUR LES
DIAGRAMMES SCHÉMATIQUES ET LA LISTE DES PIÈCES SONT
CRITIQUES POUR LA SÉCURITÉ DE FONCTIONNEMENT. NE
REMPLACER CES COMPOSANTS QUE PAR DES PIÈCES SONY
DONT LES NUMÉROS SONT DONNÉS DANS CE MANUEL OU
DANS LES SUPPLÉMENTS PUBLIÉS PAR SONY.

d

LOCATION OF CONTROL

SECTION 1

GENERAL

This section is extracted
from instruction manual.

SA-WM250

SECTION 2

DIAGRAMS

2-1. NOTE FOR PRINTED WIRING BOARDS AND SCHEMATIC DIAGRAMS

A

D

Amplifier

MONO OUT

L

R R

IN OUT

SPEAKER

INPUT

L

INPUT

SPEAKER IN

This subwoofer

INPUT

B

E

Precautions

On safety

• Before operating the subwoofer, be sure that the
operating voltage of your subwoofer is identical with
that of your local power supply.

• Unplug the subwoofer from the wall outlet if it is not to
be used for an extended period of time. To disconnect
the cord, pull the cord by grasping the plug. Never
pull the cord itself.

• Should any liquid or solid object fall into the
subwoofer, unplug the subwoofer and have the
subwoofer checked by qualified personnel before
operating it any further.

• AC power cord must be changed only at the qualified
service shop.

When turning on or off an amplifier or other
equipment

Lower the volume of the amplifier to minimum.

To avoid damaging the subwoofer

• Be careful in setting the volume control of the amplifier
to avoid an excessive input power.

• Do not attempt to open the enclosure or remold
speaker units and networks.

In case color irregularity is observed on the
nearby TV screen

With the magnetically shielded type of the speaker
system, the speakers can be installed near a TV set.
However, color irregularity may still be observed on the
TV screen depending on the type of your TV set.

If color irregularity is observed...

t Turn off the TV set once, then turn it on after 15 to

30 minutes.

If color irregularity is observed again...

t Place the speakers further apart from the TV set.

When howling occurs

Relocate the speaker or turn down the volume of the
amplifier.

On installation

• Do not install the subwoofer near heat sources such as
radiators or air ducts, or in a place subject to direct
sunlight, excessive dust, mechanical vibration or shock.

• Good ventilation is essential to prevent internal heat
build-up in the subwoofer. Place the subwoofer in a
location with adequate air circulation. Do not place the
subwoofer on a soft surface.

• Use caution when placing the speaker on a specially
treated (waxed, oiled, polished, etc.) floor, as staining
or discoloration may result.

On cleaning the cabinet

Clean the cabinet with a soft cloth lightly moistened with
water. Do not use any type of abrasive pad, scouring
powder or solvent such as alcohol or benzine.

If you have any questions or problems concerning your
subwoofer that is not covered in this manual, please
consult your nearest Sony dealer.

Installation

Since the human ear cannot detect the direction and
position where the bass sound being reproduced by a
subwoofer (below 200 Hz) comes from, you can install
the subwoofer wherever you like in your room. To
obtain a better bass reproduction, we recommend you
to install the subwoofer on a solid floor where the
resonance is unlikely to occur.

Notes

•Always install the subwoofer vertically, keeping a few
centimeters away from the wall.

• Do not place an object on the subwoofer or sit on it.

• If the subwoofer is installed in the center of a room, the
bass could be extremely weakened. This is due to the
influence of the standing wave of the room. If this
happens, move the subwoofer away from the center of
a room or eliminate the cause of the standing wave, by
installing a bookshelf on the wall, etc.

1

POWER

Amplifier

SPEAKER

L

R R

IN OUT

SPEAKER

This subwoofer

POWER indicator

L

2

Front Speaker (R) Front Speaker (L)

F

1

Hooking Up the System

Overview

Use the INPUT jacks or the SPEAKER IN terminals of the
subwoofer when you connect the amplifier.

• If your amplifier has one of the following types of
output jacks, connect the INPUT jack and the
amplifier's jack using the supplied audio connecting
cord.
— MONO OUT jack
—MIX OUT jack
— SUBWOOFER output jack(s)
— SUPER WOOFER output jack(s)

• If your amplifier does not have the above mentioned
output jacks, connect the speaker terminals of the
amplifier to the SPEAKER IN terminals instead.

Before you get started

• Turn off the power of the amplifier and the subwoofer
before making any connection.

• Use the audio connecting cords that are supplied to
the respective equipment. If there are not enough
audio connecting cords to make the necessary
connections, you need to purchase some optional
audio connecting cords.

• Be sure to make connections firmly to avoid noise.

• Connect the AC power cord from the subwoofer to
a wall outlet.

• You cannot connect the CENTER output jack for use
with Dolby Pro Logic function to the subwoofer.
Bass sound is not output with some Dolby Pro Logic
modes.

Connecting to an amplifier with a
single set of speaker terminals

If your amplifier is equipped with a single set of speaker
terminals, connect the subwoofer to the amplifier, and
then connect the front speakers to the subwoofer.

Hookups

1 Connect the subwoofer to the amplifier.

Connect the SPEAKER IN terminals of the
subwoofer to the amplifier’s speaker
terminals with the speaker cords. Be sure to
connect both L and R channels.

(B)

2 Connect the front speakers to the subwoofer.

Connect the speakers to the SPEAKER OUT
terminals of the subwoofer.

Connecting to an amplifier with
double (A+B) sets of speaker

(C)

terminals

If your amplifier has double (A+B) sets of speaker
terminals, connect both the subwoofer and the front
speakers to the amplifier.

Hookups

1 Connect the front speakers to the amplifier.

Connect the speakers to your amplifier’s
SPEAKER A terminals.

2 Connect the subwoofer to the amplifier.

Connect the SPEAKER IN terminals of the
subwoofer to the amplifier’s SPEAKER B
terminals using the supplied speaker cords.

When using the double (A+B) sets of speakers, make
sure that you select the “A+B” position with your
amplifier.

Note

When you are using SPEAKER A terminal (front
speaker) only or when the power of the amplifier is
turned off, turn down the volume or turn off the power
of the subwoofer. Otherwise, hum noise may be heard.

C

This subwoofer

L

L

R R

IN OUT

SPEAKER

PHASE

NORMAL
REVERSE

PHASE

CUT OFF FREQ

200Hz

50Hz

L

R R

IN OUT

CUT OFF FREQ

L

(D)

LEVEL

MAX

MIN

LEVEL

Connecting to an amplifier with a
special jack for a subwoofer

If your amplifier has a special jack for a subwoofer (such
as MONO OUT jack, MIX OUT jack, SUBWOOFER jack
or SUPER WOOFER jack), connect the INPUT jack of the
subwoofer to one of those jacks.

Hookups

Connect the MONO OUT jack of your amplifier to the
INPUT jack of the subwoofer with the supplied audio
connecting cord.

Note

If the output level of your amplifier is not large enough,
the sound may not be loud enough. In this case, connect
the speaker terminals of the amplifier directly to the
SPEAKER IN terminals of the subwoofer.

(A)

Connecting the AC power cord

• Connect the AC power cord from the subwoofer and
from your amplifier to a wall outlet.

• Make sure that power to the subwoofer is turned off

before you plug in or unplug any power cord.

Listening to the Sound (E)

1 Turn on the amplifier and select the program

source.

2 Press POWER.

The subwoofer turns on and the POWER
indicator lights up in green.

3 Play the program source.

Adjust the VOLUME so that sound from the
front speakers is not distorted.
If it is distorted, the sound from the
subwoofer will also be distorted.

Notes

• Never set the amplifier’s tone control (BASS, TREBLE,

etc.) or the equalizer output to a high level or input
sinewaves of 20 Hz to 50 Hz recorded on a
commercially-available test disc or special sound (bass
sound of electronic musical instrument, pop noise of
analog disc turntable, sound with abnormally
enhanced bass, etc.) in a high level to this unit. These
actions may cause damage to the speakers.
When a special disc containing abnormally enhanced
bass is played, noise may be output in addition to the
original sound. In such a case, reduce the sound level.

• The subwoofer output signal (DOLBY digital signal)

of the digital surround processor sold singularly is set
10 dB higher by Dolby laboratories Licensing
Corporation. In the case of using normally, adjust the
subwoofer level.

1

Front Speaker (R)

2

100Hz

Amplifier

SPEAKER A

Front Speaker (L)

2

G

150Hz

120Hz

1

2

200Hz

50Hz

3

4

75Hz

Adjusting the Sound

You can adjust the sound of the subwoofer to suit the
sound of your front speakers. Reinforcing the bass sound
gives you a greater sense of atmosphere.

1 Adjust the cut-off frequency.

Turn the CUT OFF FREQ control, depending
on the reproduction frequencies of your front
speakers.

Refer to the following when adjusting.
1 Typical very small sized speakers: 5 – 7 cm

dia.

2 Typical small sized speakers: 8 –15 cm dia.
3 Typical medium sized speakers: 16 –24 cm

dia.

4 Typical large sized speakers: more than 25

cm dia.

To make the most of the low level converter
function of Dolby digital, turn the CUT OFF
FREQ as high as possible when playing back
the Dolby digital.

2 Adjust the volume level of the subwoofer.

Turn the LEVEL control so that you can hear
the bass sound a little more than before. To
increase the volume, turn the LEVEL control
clockwise. To reduce the volume, turn the
LEVEL control counterclockwise.

3 Play your favorite song and movie.

Male vocal tunes and voice containing bass
sounds are most suitable for adjustment.
Turn the volume for front speakers to the
same level as usual.

4 Select the phase polarity.

Use the PHASE selector to select the phase
polarity.

5 Repeat steps 1 to 4 to adjust for your

preference.
Once you have adjusted the subwoofer to the

settings you want, use the VOLUME control
on the amplifier to adjust the volume of the
subwoofer with that of the other speakers.
You don’t need to adjust the subwoofer
settings when you change the volume level
of the amplifier.

Notes

• If the sound distorts when you turn on the bass
reinforcement from your amplifier (such as, DBFB,
GROOVE, the graphic equalizer, etc.), turn off the bass
reinforcement and adjust the sound.

• Do not turn the volume of the subwoofer to maximum.
Doing so may weaken the bass sound. Moreover,
extraneous noise may be heard.

• Selecting NORMAL or REVERSE with the PHASE
selector reverses the polarity and may provide better
bass reproduction in certain listening environments
(depending on the type of front speakers, the position
of the subwoofer and the adjustment of the cut-off
frequency). It may also change the expanse and
tightness of sound, and effect the feeling of the sound
field. Select the setting that provides the sound you
prefer when listening in your normal listening position.

Setting the speaker (G)

To prevent speaker vibration or movement while
listening, attach the supplied foot pads to the speaker.

Foot pads

Amplifier

SPEAKER B

L

R R

IN OUT

SPEAKER

This subwoofer

(F)

THIS NOTE IS COMMON FOR PRINTED WIRING
BOARDS AND SCHEMATIC DIAGRAMS.
(In addition to this, the necessary note is printed
in each block.)

L

For schematic diagrams.

Note:

• All capacitors are in µF unless otherwise noted. pF: µµF
50 WV or less are not indicated except for electrolytics
and tantalums.

• All resistors are in Ω and 1/
specified.

f

•

: internal component.

• C : panel designation.

Note:

The components identi­fied by mark 0 or dotted
line with mark 0 are criti­cal for safety.
Replace only with part
number specified.

• A : B+ Line.

• B : B– Line.

•Voltages are dc with respect to ground under no-signal
(detuned) conditions.

no mark : Power on

•Voltages are taken with a VOM (Input impedance 10 MΩ).
Voltage variations may be noted due to normal produc­tion tolerances.

• Signal path.
F : AUDIO

•Abbreviation
CND : Canadian model.
MY : Malaysia model.
SP : Singapore model.
TW : Taiwan model.

4

W or less unless otherwise

Note:

Les composants identifiés par
une marque 0 sont critiques
pour la sécurité.
Ne les remplacer que par une
piéce portant le numéro
spécifié.

For printed wiring boards.

Note:

• X : parts extracted from the component side.

• Y : parts extracted from the conductor side.

• : Pattern from the side which enables seeing.

•Abbreviation
CND : Canadian model.
MY : Malaysia model.
SP : Singapore model.

2-2. CIRCUIT BOARDS LOCATION

INPUT CONTROL board

MAIN board

CONTROL board

POWER TRANS boar

SWITCH board

33

SA-WM250

2-3. PRINTED WIRING BOARDS — MAIN SECTION — • Refer to page 3 for Circuit Boards Location. : Uses unleaded solder.

A

B

C

D

E

F

1

234567891011 12 13 14

(Page 6) (Page 5) (Page 5)(Page 6)

RV801

JW

G1

CN402

C402

JW123

JW125

R403

D401

C407

JW101

JW102

C406

JW

C411

C401

124

403

C412

C403

R401

C405

D402

R402

C404

R506

R404

C409

C408

JW126

R500

D403

Q505

D502

R507

CN301

C410

R313

D302

D301

R317

C318

JW404

R315

R501

JW

JW

R504

JW105

103

104

JW127

R309

JW301

JW

D501

JW106

C303

501

C502

JW108

JW107

JW

R502

R311

JW110

128

R503

C301

C312

R303

R302

C302

JW112

Q502

JW109

Q501

R505

JW111

R314

C501

R508

D304

R305

C311

RY301

C314

C304

R301

IC301

Q504

R304

R312

JW129

C313

Q503

C305

C503

CN204

D602

R601

JW114

C306

JW115

JW

R310

135

C310

C205

D205

R307

C601

JW118

C309

C308

JW116

D206

JW117

R306

CN202

C206

C307

JW

132

JW119

C317

R208

C316

IC202

R207

CN201

R205

JW122

C204

JW

JW

R308

R211

R210

133

134

C203

CNP111

131

JW

130

JW

121

JW

120

JW

IC203

R215

C210

R217

C801

G2

CNP801

C211

C209

R216

• Semiconductor
Location

Ref. No. Location
D205 D-8

D206 D-8
D301 F-4
D302 F-4
D304 C-6
D401 C-3
D402 C-4
D403 C-4
D501 B-5
D502 F-4
D602 B-8

IC202 D-9
IC203 D-10
IC301 F-7

Q501 B-6
Q502 C-6
Q503 B-7
Q504 B-7
Q505 F-4

44

2-4. PRINTED WIRING BOARD — INPUT CONTROL SECTION — • Refer to page 3 for Circuit Boards Location. : Uses unleaded solder.

SA-WM250

A

B

C

D

1

C703

R702

R706

234567891011 12 13 14

(Page 4) (Page 4)

R701

IC701

C706

JW702

R707

C705

R705

R704

JW701

R708

R703

JW207

RV701

JW209

CN701

C704

C701

J101

C702

C201

CN101

JW205

R201

R102

R202

R204

JW206

R104

R101

JW204

R103

R105

R203

IC201

R106

JW208

R108

D203

D204

D202

D201

R107

JW210

R109

E

F

S701

C101

R110

TM101

• Semiconductor
Location

Ref. No. Location
D201 C-12

D202 C-12
D203 C-11
D204 C-12

55

IC201 C-10
IC701 C-2