JVC KSAX-4500 Service manual

SERVICE MANUAL

POWER AMPLIFIER

KS-AX4500

KS-AX4500KS-AX4500

Caution

If electricity is connected during disassembly, it must be a no load current. If it is load
current, be sure to attach a heat sink to the power-amp IC. This will be damaged if the
above precautions are not followed, as it does not have a sub heat sink attached to it.

Contents

Safety precaution
Location of main parts
Removal of main parts
Test method
Description of major ICs

1-2
1-3
1-5
1-7
1-8

Area Suffix

E

Continental Europe

J

Northern America

COPYRIGHT 2001 VICTOR COMPANY OF JAPAN, LTD.

No. 49622

Apr. 2001

KS-AX4500

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.

1-2

Location of main parts

CONTROL PANEL

KS-AX4500

HEAT SINK

REAR PANEL

OUTPUT TERMINAL for FRONT(L/R)

FRONT PANEL

SWITCH KNOB VOLUME KNOB

INPUT for POWER

LOW INPUT jack for REAR(R)

LOW INPUT jack for FRONT(R)

FUSE

HEAT SINK

OUTPUT TERMINAL for REAR(L/R)

HEAT SINK

HIGH INPUT connector for REAR

LOW INPUT jack for REAR(L)

HIGH INPUT connector for FRONT

LOW INPUT jack for FRONT(L)

1-3

KS-AX4500

GND wire

DIODE

HEAT SINK
(Bottom view)

MAIN PCB

SUB PCB

POWER TRANSISTER

1-4

POWER FET

MAIN PCB

POWER TRANSISTER

Removal of main parts

KS-AX4500

CAUTION:

If electricity is connected during disassembly,
it must be a no load current. If it is load
current, be sure to attach a heat sink to the
power-amp IC. This will be damaged if the
above precautions are not followed, as it
does not have a sub heat sink attached to it.

Removing the bottom cover (see Fig. 1)

1.

From the bottom side of the main unit, remove the 4
screws A retaining the bottom cover.

2.

Then remove the 6 screws B retaining the bottom
cover.

3.

Remove the bottom cover.

Removing the MAIN PCB

(see Fig. 2 to 8)

1.

Remove the bottom cover from the main unit.

A

B

B

Bottom cover

A

Fig. 1

Top panel

2.

Loosen and remove the 2 screws C retaining the top
plate on the main unit. (Stoppers are attached to the
backs of the C screws so that they cannot be
removed easily.)

3.

Remove the 4 volume knobs on top of the control
panel. If it cannot be pulled out easily, insert a rope
or wire between the base of the volume knob and the
control panel so that the volume knob is raised a little
above the surface and then remove it.

(Be careful when inserting a lever etc. not to
scratch the surface of the control panel).

4.

Remove the 4 screws D retaining the control panel.
Then detach the control panel and the switch knobs.

C

Fig. 2

Volume knob

D D

Volume knob

Switch knob

Fig. 3

Rope or wire

Control panel

Control panel

C

(Side view)

Fig. 4

1-5

KS-AX4500

5.

Remove the 13 screws E retaining the panels on
both sides of the main unit.

E

Rear panel

6.

Remove the 14 screws F attaching the MAIN PCB to
the bottom of the main unit.

E

E

E

Fig. 5

Front panel

Fig. 6

F

F

7.

Remove the MAIN PCB by lift up the arrow mark.

MAIN PCB

F

Fig. 7

MAIN PCB

(Side view)

Fig. 8

1-6

Test method

5

6

7

3

R01

R60

C01

J09

Q01

C31

C68

Check the voltage and frequency of the secondary

1.
toroidal coil.

KS-AX4500

FREQUENCY COUNTER

.

Measure the secondary toroidal coil, if the standard

2.

FREQUENCY:22.87kHz ± 50Hz
VOLTAGE VALUE:60Vp-p ± 2.5V

frequency value of 22.87 kHz ± 50 Hz is not attained,
measure the R60 terminal, then adjust the SV01 so
that the R60 terminal becomes 22.87 kHz ± 50Hz.

Note:

When measuring, adjust and apply power
with no signal or load on each board.

TEST SET

MAIN PCB

MAIN PCB

(+)
(

POWER SUPPLY

14.4V

-

)

Measuring
Points

DC/DC CONVERTER SECOND GENERATOR SWITCHING

TEST ITEM

VOLTAGE TEST

FREQUENCY CHECK

SPECIFICATION CONDITION

60Vp-p±2.5V

22.87KHz±50Hz

OSCILLOSCOPE
VOLT/DIV: 10
TIME/DIV: 10mcec

60Vp-p

±2.5V

1-7

KS-AX4500

Description of major ICs

PIN CONNECTIONS

Noninv

Input

Inv

Input

Compen/PWN

Comp Input

Dead Time

Control

C

R

Ground

C1

1

2

3

4

5

T

6

T

7

8

(TOP View)

16

15

14

13

12

11

10

9

Noninv
Input

Inv
Input

V

ref

Output
Control

V

CC

C2

E2

E1

TL494

6

5

4

1

Oscillator

0.12V

0.7V

0.7mA

Dead-Time
Comparator

PWM
Comparator

2

Flip­Flop

Ck Q

UV

Lockout

QD

3.5V

13

8

Q1

9

11

Q2

10

12

4.9V

Reference
Regulator

7141615321

1-8

VICTOR COMPANY OF JAPAN, LIMITED

MOBILE ELECTRONICS DIVISION
PERSONAL & MOBILE NETWORK B.U. 10-1,1Chome,Ohwatari-machi,Maebashi-city,Japan

(No. 49622)

Printed in Japan
200104(S)