SERVICE MANUAL
POWERED SUBWOOFER
MB38820053
SP-DWF31
Area suffix
B ------------------------------ U.K.
E ---------- Continental Europe
EV ------------- Eastern Europe
TABLE OF CONTENTS
1 PRECAUTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3
2 SPECIFIC SERVICE INSTRUCTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-5
3 DISASSEMBLY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-6
4 ADJUSTMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-9
5 TROUBLESHOOTING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-9
COPYRIGHT © 2005 Victor Company of Japan, Limited
No.MB388
2005/3
SPECIFICATION
Type Powered Subwoofer Bass-reflex type (magnetically shielded type)
Speaker 16.0 cm cone × 1
Frequency Range 32 Hz 200 Hz
Impedance 4 Ω
Input terminals INPUT (LOW-LEVEL)
Power requirements AC 230 V , 50 Hz
Output power of built-in amp 100 W (50 Hz, 4 Ω, 10 % THD)
Power Handling Capacity 27 W
Dimensions (W × H × D) 184 mm × 374 mm × 354 mm
Mass 8.2 kg
Design and specifications are subject to change without notice.
1-2 (No.MB388)
SECTION 1
PRECAUTIONS
1.1 Safety Precautions
(1) This design of this product contains special hardware and
many circuits and components specially for safety purposes. For continued protection, no changes should be made
to the original design unless authorized in writing by the
manufacturer. Replacement parts must be identical to
those used in the original circuits. Services should be performed by qualified personnel only.
(2) Alterations of the design or circuitry of the product should
not be made. Any design alterations of the product should
not be made. Any design alterations or additions will void
the manufacturers warranty and will further relieve the
manufacture of responsibility for personal injury or property
damage resulting therefrom.
(3) Many electrical and mechanical parts in the products have
special safety-related characteristics. These characteristics are often not evident from visual inspection nor can the
protection afforded by them necessarily be obtained by using replacement components rated for higher voltage, wattage, etc. Replacement parts which have these special
safety characteristics are identified in the Parts List of Service Manual. Electrical components having such features
are identified by shading on the schematics and by ( ) on
the Parts List in the Service Manual. The use of a substitute
replacement which does not have the same safety characteristics as the recommended replacement parts shown in
the Parts List of Service Manual may create shock, fire, or
other hazards.
(4) The leads in the products are routed and dressed with ties,
clamps, tubings, barriers and the like to be separated from
live parts, high temperature parts, moving parts and/or
sharp edges for the prevention of electric shock and fire
hazard. When service is required, the original lead routing
and dress should be observed, and it should be confirmed
that they have been returned to normal, after reassembling.
(5) Leakage shock hazard testing
After reassembling the product, always perform an isolation check on the exposed metal parts of the product (antenna terminals, knobs, metal cabinet, screw heads,
headphone jack, control shafts, etc.) to be sure the product
is safe to operate without danger of electrical shock.Do not
use a line isolation transformer during this check.
• Plug the AC line cord directly into the AC outlet. Using a
"Leakage Current Tester", measure the leakage current
from each exposed metal parts of the cabinet, particularly any exposed metal part having a return path to the
chassis, to a known good earth ground. Any leakage current must not exceed 0.5mA AC (r.m.s.).
• Alternate check method
Plug the AC line cord directly into the AC outlet. Use an
AC voltmeter having, 1,000Ω per volt or more sensitivity
in the following manner. Connect a 1,500Ω 10W resistor
paralleled by a 0.15µF AC-type capacitor between an ex-
posed metal part and a known good earth ground.
Measure the AC voltage across the resistor with the AC
voltmeter.
Move the resistor connection to each exposed metal
part, particularly any exposed metal part having a return
path to the chassis, and measure the AC voltage across
the resistor. Now, reverse the plug in the AC outlet and
repeat each measurement. Voltage measured any must
not exceed 0.75 V AC (r.m.s.). This corresponds to 0.5
mA AC (r.m.s.).
AC VOLTMETER
(Having 1000
ohms/volts,
or more sensitivity)
0.15 F AC TYPE
Place this
probe on
1500 10W
Good earth ground
1.2 Warning
(1) This equipment has been designed and manufactured to
meet international safety standards.
(2) It is the legal responsibility of the repairer to ensure that
these safety standards are maintained.
(3) Repairs must be made in accordance with the relevant
safety standards.
(4) It is essential that safety critical components are replaced
by approved parts.
(5) If mains voltage selector is provided, check setting for local
voltage.
1.3 Caution
Burrs formed during molding may be left over on some parts
of the chassis.
Therefore, pay attention to such burrs in the case of preforming repair of this system.
1.4 Critical parts for safety
In regard with component parts appearing on the silk-screen
printed side (parts side) of the PWB diagrams, the parts that are
printed over with black such as the resistor ( ), diode ( )
and ICP ( ) or identified by the " " mark nearby are critical
for safety. When replacing them, be sure to use the parts of the
same type and rating as specified by the manufacturer.
(This regulation dose not Except the J and C version)
each exposed
metal part.
(No.MB388)1-3
1.5 Safety Precautions (U.K only)
(1) This design of this product contains special hardware and many circuits and components specially for safety purposes. For con-
tinued protection, no changes should be made to the original design unless authorized in writing by the manufacturer. Replacement parts must be identical to those used in the original circuits.
(2) Any unauthorised design alterations or additions will void the manufacturer's guarantee; furthermore the manufacturer cannot
accept responsibility for personal injury or property damage resulting therefrom.
(3) Essential safety critical components are identified by ( ) on the Parts List and by shading on the schematics, and must never
be replaced by parts other than those listed in the manual. Please note however that many electrical and mechanical parts in
the product have special safety related characteristics. These characteristics are often not evident from visual inspection. Parts
other than specified by the manufacturer may not have the same safety characteristics as the recommended replacement parts
shown in the Parts List of the Service Manual and may create shock, fire, or other hazards.
(4) The leads in the products are routed and dressed with ties, clamps, tubings, barriers and the like to be separated from live parts,
high temperature parts, moving parts and/or sharp edges for the prevention of electric shock and fire hazard. When service is
required, the original lead routing and dress should be observed, and it should be confirmed that they have been returned to
normal, after re-assembling.
1.5.1 Warning
(1) Service should be performed by qualified personnel only.
(2) This equipment has been designed and manufactured to meet international safety standards.
(3) It is the legal responsibility of the repairer to ensure that these safety standards are maintained.
(4) Repairs must be made in accordance with the relevant safety standards.
(5) It is essential that safety critical components are replaced by approved parts.
(6) If mains voltage selector is provided, check setting for local voltage.
Burrs formed during molding may be left over on some parts of the chassis. Therefore,
pay attention to such burrs in the case of preforming repair of this system.
1-4 (No.MB388)
SECTION 2
SPECIFIC SERVICE INSTRUCTIONS
This service manual does not describe SPECIFIC SERVICE INSTRUCTIONS.
(No.MB388)1-5
SECTION 3
A
r
DISASSEMBLY
3.1 Removing the amplifier assembly (See Figs.1 and 2)
(1) From the back side of the main body, remove the eleven
screws A attaching the amplifier assembly. (See Fig.1.)
(2) Take out the amplifier assembly from the main body. (See
Fig.2.)
(3) Disconnect the wire connector from the back side of the
amplifier assembly. (See Fig. 2.)
(4) Disconnect the wire from the terminal of the cone speaker.
(See Fig.2.)
3.2 Removing the back panel (See Figs.1 and 3)
(1) From the back side of the main body, remove the eleven
screws A attaching the amplifier assembly. (See Fig.1.)
Reference:
Remove the amplifier assembly from the main body as
required. (See Fig.2.)
(2) Remove the five screws B attaching the back panel. (See
Fig.3.)
A
A
Amplifier assembly
A
A
A
Fig.1
mplifier assembly
Wire connector
Fig.2
Back panel
B
Terminal
Cone speake
B
1-6 (No.MB388)
Fig.3
3.3 Removing the power cord (See Figs.4 and 5)
• Prior to performing the following procedures, remove the back
panel.
(1) Remove the two screws C attaching the bracket (cord).
(See Fig.4.)
Reference:
Remove the amplifier assembly from the main body as
required. (See Figs.1 and 2.)
(2) Draw the power cord a little toward this side and remove
the bracket (cord) in the direction of the arrow. (See Fig.4.)
(3) Remove the strain relief. (See Fig.4.)
(4) Disconnect the power cord from the connector CN901
the power switch board. (See Fig.5.)
3.4 Removing the amplifier board assembly (Amp board, volume board, switch board) (See Figs.5 and 6)
• Prior to performing the following procedures, remove the back
panel and the power cord.
Reference:
Remove the amplifier assembly from the main body as required. (See Figs.1 and 2.)
(1) Pull a push button out of the switch board. (See Fig.5.)
(2) Remove the two screws D and three screws E attaching
the bracket (knob) and take out the bracket (knob). (See
Fig 5.)
(3) Disconnect the wire from the connectors (CN102
on the amp board. (See Fig.5.)
(4) Remove the amplifier board assembly from the connectors
(CN951
(5) Take out the amplifier board assembly.
, CN952) on the regulator board. (See Fig.6.)
on
, CN503)
Bracket (cord)
Push button
CN503
CN102
E
Strain relief
C
Fig.4
Bracket (knob)
Volume board
C
Power cord
E
D
E
D
3.5 Removing the power supply board assembly (Regulator board, power switch board) (See Fig.6)
• Prior to performing the following procedures, remove the back
panel, power cord and amplifier board assembly.
Reference:
Remove the amplifier assembly from the main body as required. (See Figs.1 and 2.)
(1) Remove the screw F attaching the bracket (switch) and re-
move the bracket (switch) in the direction of the arrow.
(2) Remove the two screws G and four screws H attaching the
regulator board.
(3) Take out the power supply board assembly.
Amp board
CN952
CN951
CN901
Switch board
Power switch board
Fig.5
G
Regulator board
HH
Power switch board
F
Fig.6
Bracket (switch)
(No.MB388)1-7
3.6 Removing the speaker net (See Fig 7)
From the side of the main body, insert the tip of the flat-bladed
screwdriver or similar tool into the space between the main body
and speaker net, and lift the speaker net little by little to remove.
Note:
To prevent damaging the speaker net and main body, insert
cushioning plates etc. and below the tip of the flat-bladed
screwdriver or similar tool.
From the right side of the main body, release the eight joints a
and remove the speaker net from the main body.
3.7 Removing the cone speaker (See Fig 8 and Fig 9)
• Prior to performing the following procedures, remove the
speaker net.
(1) Remove the six screws J attaching the cone speaker. (See
Fig.8.)
(2) Take out the cone speaker from the main body. (See Fig 9.)
(3) Disconnect the wires from the terminal of the cone speak-
er. (See Fig 9.)
Speaker net
Main body
a
Cushioning
plate,etc.
Fig.7
Cone speaker
Flat-bladed
screwdriver,etc.
a
J
a
J
a
Fig.8
J
a
J
1-8 (No.MB388)
Main body
Terminal
Cone speaker
Fig.9
SECTION 4
ADJUSTMENT
This service manual does not describe ADJUSTMENT.
SECTION 5
TROUBLESHOOTING
This service manual does not describe TROUBLESHOOTING.
(No.MB388)1-9
Victor Company of Japan, Limited
AV & MULTIMEDIA COMPANY AUDIO/VIDEO SYSTEMS CATEGORY 10-1,1chome,Ohwatari-machi,Maebashi-city,371-8543,Japan
(No.MB388)
Printed in Japan
VPT
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