JVC SX-DD3 Service Manual

SERVICE MANUAL

SPEAKER SYSTEM

SX-DD3

Area suffix
E ------ Continental Europe

EN ------- Northern Europe

SX-DD3

Contents

Safety precautions --------------------------------------------------------1-2
Disassembly method -----------------------------------------------------1-3
Description of major ICs -------------------------------------------------1-6,7

COPYRIGHT 2002 VICTOR COMPANY OF JAPAN, LTD.

No.21092

Apr. 2002

SX-DD3

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. Alter ations 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 manufacturer`s warr anty 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 re-assembling.

5. Leakage currnet check (Electrical shock hazard testing)
After re-assembling 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, 1,000 ohms per volt or more
sensitivity in the following manner. Connect a 1,500 10W resistor paralleled by a 0.15 F AC-type capacitor
between an exposed 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 meausre the AC voltage across the resistor.

0.15 F AC TYPE

AC VOLTMETER
(Having 1000
ohms/volts,
or more sensitivity)

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.).

Good earth ground

1500 10W

!

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 m ust 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.

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.

Place this
probe on
each exposed
metal part.

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.

(This regulation does not correspond to J and C version.)

1-2

SX-DD3

r

.

r

y.

t

e

.

t

.

d

g

)

y.

b.

3.

1

3

t

er

t

4

Disassembly metho

Removing the amplifier assembly
(See Fi

Remove the eleven screws A attaching the amplifie
assembly.

Pull out the amplifier assembly
Remove the felt sheet from vibration prevention of

the wire connector in the reverse side of the amplifie
assembl

Remove the connection of 3 wire connectors in the
reverse side of the amplifier assembly.

Note: Before attaching the amplifier assembly the fel
sheet is wound to the wire connector for th
vibration prevention of the wire connector
Attaching the tie band from the top of the fel
sheet

. 1~3

Cabine

A

Fig.

A

A

Rear panel

A

Tie band

Removing the rear panel (See Fig. 4)

Remove the amplifier assembl

move the volume kno

Remove the three screws B attaching the rear panel .

Amp. assay

Vol. knob

B

Felt sheet

abine

Amp.

ord

onnect

Felt sheet

Fig.

Rear panel

.

1-3

SX-DD3

y.

.

899.

g

)

3.

)

.

.

.

3.

.

d.

.

3.

)

l

er s

ch

h

ch

e

d

/CN821

851

.

d

891N821

Removing the power switch board

(See Fi

Remove the amplifier assembl
Remove the three screws C attaching the bracket.
Pull out the power switch board to the rear side
Remove the wire connecter CN

Note:As occasion demands the tie band is cut.

Remove terminal board (See Fig. 6,7

Remove the rear panel

. 5

CN899

Pow

power switc

wit

board

knob

Bracket a

C

Fig. 5

Remove the two screws D attaching the bracket b.
Removing the connection of connector CN811 and

CN821, pull out the terminal board
Remove the wire connecter CN851

rminal boar

T

N811

Fig. 7

N

Remove amplifier board (See Fig. 8

Remove the rear panel
Remove terminal boar

Bracket b

D

Phase swit

knob

Termina

oard

Fig. 6

E

Amp

oar

N

CN881

E

1-4

Removing the connection of wire connector CN891
and CN881

Remove the six screws E attaching the amplifier

oard.

Fig. 8

SX-DD3

er

t

er

Remove the transformer (Fig. 9)

Remove the rear panel.

1.

Remove the power switch board.

2.

Remove the terminal board.

3.

Remove the four screws F which are fixing the
transformer.

Remove the woofer (Fig. 10~12)

Remove the Bottom board.

1.

Remove the four screws G which are fixing the
bottom board.

2.

Remove the four screws H which are fixing the
woofer speaker.

3.

Pull out woofer speaker.

F

Transformer

Fig. 9

G

G

4.

Remove the speaker wire.

Cautions:

A black wire terminal is not a ground.
These goods should not make the
terminal black of a speaker absolutely
touched from the structure of a system to
the ground of a chassis etc.

Bottom board

Fig. 10

H

Woof

abine

Fig. 11

Woof

Speaker wire

Fig. 12

(red, black)

1-5

SX-DD3

Description of major ICs

STK411-290E (IC821) : Power amp.

1.Block diagram

3

1

5

4

2

7

SUB

6

8

R31

TR31

Comparator

TR14 TR13

R14

TR21

D7

D35

R16

D33

D31

R12
C3

R19

TR15

TR16

TR20

R15

D32

R16

D34

R17

TR19

TR17

C6

D36

Comparator

R18

R32

TR32

916
22

21

R13

1-6

17

D6

R4

TR9

TR1 TR2

TR11 TR23

TR6

C2

C1
R2

R9

18

TR24

R5

TR4

TR3

TR12

TR8

19

R6

TR22

TR10

20

TR7

R7

C5

TR5

11
15

14
10

R8

R51

12 13

D1

R3

NJM4580D (IC811,IC812,IC813) Dual ope. amp.

1. Pin layout

SX-DD3

2. Block diagram

+

V

INPUT

+

A OUT

A -IN

A +IN

V

1

2

A

3

-

4

(TOP VIEW)

B

8

7

6

5

+

V

B OUT

B -IN

B +IN

OUTPUT

-

V

TC74HCU04AP (IC851) : 2ch NOR gate

1. Pin layout

1

1A
1Y
2A
2Y
3A
3Y

GND

2
3
4
5
6
7

14
13
12
11
10
9
8

VCC
6A
6Y
5A
5Y
4A
4Y

2. Truth value table

A
L
H

Y
H
L

1-7

SX-DD3

VICTOR COMPANY OF JAPAN, LIMITED

AUDIO & COMMUNICATION BUSINESS DIVISION
PERSONAL & MOBILE NETWORK BUSINESS UNIT. 10-1,1chome,Ohwatari-machi,Maebashi-city,371-8543,Japan

(No.21092)

200204