SA-WM250 - Sony Audio Service Manual (repair manual). Page 3

3

3

CONTROL board

POWER TRANS board

SWITCH board

INPUT CONTROL board

MAIN board

This section is extracted
from instruction manual.

 INPUT

 SPEAKER IN

Amplifier

This subwoofer

This subwoofer

Front Speaker (R)

Front Speaker (L)

A

1

B

2

1

C

2

LEVEL

PHASE

E

POWER

1

F

Amplifier

This subwoofer

MONO OUT

D

CUT OFF FREQ

Front Speaker (R)

Front Speaker (L)

Amplifier

This subwoofer

Amplifier

200Hz

NORMAL

REVERSE

50Hz

MAX

MIN

4

3

2

1

50Hz

200Hz

75Hz

120Hz 150Hz

100Hz

2

G

Foot pads

POWER indicator

• 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.

Lower the volume of the amplifier to minimum.

• 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.

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.

t

Turn off the TV set once, then turn it on after 15 to
30 minutes.

t

Place the speakers further apart from the TV set.

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

• 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.

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.

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.

• 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.

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.  (

A

)

• 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 (B)

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.

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.

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
terminals (C)

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

Connect the front speakers to the amplifier.

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

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.

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.

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 (D)

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

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.

• 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)

Turn on the amplifier and select the program
source.

Press POWER.

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

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.

• 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.

Adjusting the Sound (F)

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.

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.

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.

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.

Select the phase polarity.

Use the PHASE selector to select the phase
polarity.

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.

• 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.

G

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

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

/

4

 

W or less unless otherwise

specified.

•

f

: internal component.

•

C

: panel designation.

• 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.

TW

: Taiwan model.

TH

: Thai model.

KR

: Korea model.

•

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 M

Ω

).

Voltage variations may be noted due to normal produc-
tion tolerances.

• Signal path.

F

: AUDIO

• Abbreviation

CND : Canadian model.
MY

: Malaysia model.

SP

: Singapore model.

TW

: Taiwan model.

TH

: Thai model.

KR

: Korea model.

Note:
The components identi-
fied by mark 

0

 or dotted

line with mark 

0

 are criti-

cal for safety.
Replace only with part
number specified.

Note:
Les composants identifiés par
une marque 

0

 sont critiques

pour la sécurité.
Ne les remplacer que par une
piéce portant le numéro
spécifié.