1
SA-WM20
SERVICE MANUAL
ACTIVE SUBWOOFER
US Model
Canadian Model
AEP Model
UK Model
E Model
SPECIFICATION
Ver.1.0 2001.1
Sony Corporation
Audio Entertainment Group
General Engineering Dept.
9-873-806-11
2001A0900-1
© 2001. 1
System
Type
Active Subwoofer (magnetically shielded design)
Speaker unit
Woofer: 20 cm dia. (8 in.), cone type
Amplifiersection
Continuous RMS output :
Canadian model (0.8%) 50W
European model (DIN) 50 W
Other models (0.8%) 50 W
Reproduction frequency range
28 Hz 200 Hz
High frequency cut-off frequency
50 Hz 200 Hz
Phase selector
NORMAL, REVERSE
Inputs
Input jacks
LINE IN: input pin jack
SPEAKER IN: input terminals
Output jacks
SPEAKER OUT: output terminals
General
Power requirements
Canadian model: 120 V AC, 60 Hz
European model: 230 V AC, 50/60 Hz
Power consumption
50 W
Dimensions
Approx. 270 x 325 x 385 mm
(10 3/
4 x 12
7/
8 x 15
1/
4 in.) (w/h/d)
Mass
10 kg (22 lb 1oz)
Supplied accessories
Foot pads (4)
Audio connecting cord (1 phono plug 1 phono
plug), 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.
2
SA-WM20
TABLE OF CONTENTS
1. GENERAL .......................................................................... 3
2. DIAGRAMS
2-1. Circuit Boards Location ........................................................ 3
2-2. Printed Wiring Board ............................................................ 4
2-3. Schematic Diagram ............................................................... 5
3. EXPLODED VIEW
3-1. Front Section ......................................................................... 6
3-2. Amp Section ......................................................................... 6
4. ELECTRICAL PARTS LIST ......................................... 7
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 PART NUMBERS
APPEAR AS SHOWN IN THIS MANUAL OR IN SUPPLEMENTS
PUBLISHED BY SONY.
ATTENTION AU COMPOSANT AYANT RAPPORT
À LA SÉCURITÉ!
LES COMPOSANTS IDENTIFÉS 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 PIÈSES SONY
DONT LES NUMÉROS SONT DONNÉS DANS CE MANUEL OU
DANS LES SUPPÉMENTS PUBLIÉS PAR SONY.
After correcting the original service problem, perform the
following safety checks 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
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 microamperes).
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 low-voltage
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 2V AC range are suitable. (See
Fig. A)
SAFETY CHECK-OUT
(US model)
Fig. A. Using an AC voltmeter to check AC leakage.
0.15
µF
To Exposed Metal
Parts on Set
1.5k
AC
voltmeter
(0.75V)
Earth Ground
3
SECTION 1
GENERAL
· Location of controls
Front view (a part)
1
2
3
4
5
1 POWER (@/1) button
2 POWER indicator
3 PHASE (4 NORMAL/$ REVERSE) button
4 CUT OFF FREQ dial
5 LEVEL dial
3
SA-WM20
SECTION 2
DIAGRAMS
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
and 1/4 W or less unless otherwise
specified.
·
C : panel designation.
For printed wiring boards.
Note:
·
X : parts extracted from the component side.
·
Y : parts extracted from the conductor side.
·
b : Pattern from the side which enables seeing.
·
: B+ Line.
·
: B Line.
· Voltages are dc with respect to ground under no-signal con-
ditions.
no mark : Power on
: Impossible to measure
· Voltages are taken with a VOM (Input impedance 10M
).
Voltage variations may be noted due to normal preduction
tolerances.
· Signal path.
K : AUDIO
THIS NOTE IS COMMON FOR PRINTED WIRING BOARDS AND
SCHEMATIC DIAGRAMS.
(In addition to this, the necessary note is printed in each block.)
2-1. Circuit Boards Location
MAIN board
POWER IC board
LED board
SWITCH board
CONTROL board
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 por tant le numéro
spécifié.
· Abbreviation
CND : Canadian model
SP
: Singapore model
MX
: Mexican model
MY
: Malaysia model
44
SA-WM20
2-2. PRINTED WIRING BOARD
· See page 3 for Circuit Boards Location.
D101
A-2
D102
A-2
D103
A-2
D104
A-2
D301
B-3
D302
B-3
D303
C-5
D304
A-6
D401
A-7
D402
A-6
D403
A-4
D404
A-4
IC101
B-1
IC102
A-3
Q301
C-4
Q302
C-4
Q303
C-5
Q304
C-4
Q401
B-1
· Semiconductor
Location
Ref. No.
Location
There are a few cases that the part isn't mounted in
model is printed on diagram.