JVC KS-FX490 Service Manual

SERVICE MANUAL

CASSETTE RECEIVER

4984520035

KS-FX490

Area Suffix

J ------ Northern America

TABLE OF CONTENTS

1 Precautions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3

2 Disassembly method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

3 Adjustment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

4 Description of major ICs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

No.49845

2003/5

SPECIFICATION

AUDIO AMPLIFIER SECTION

TUNER SECTION Frequency Range FM 87.5 MHz to 107.9 MHz

CASSETTE DECK SECTION

GENERAL Power Requirement Operating Voltage DC 14.4 V (11 V to 16 V allowance)

Maximum Power Output Front 50 W per channel

Rear 50 W per channel

Continuous Power Output (RMS) Front 19 W per channel into 4 Ω, 40 Hz to 20 000 Hz at no more

than 0.8 % total harmonic distortion.

Rear 19 W per channel into 4 Ω, 40 Hz to 20 000 Hz at no more

than 0.8 % total harmonic distortion.

Load Impedance 4 Ω (4 Ω to 8 Ω allowance)

Tone Control Range Bass ±10 dB at 100 Hz

Treble ±9 dB at 10 kHz

Frequency Response 40 Hz to 20 000 Hz

Signal-to-Noise Ratio 70 dB

Line-Out Level/Impedance 2.0 V/20 kΩ load (250 nWb/m)

AM 530 kHz to 1 710 kHz

[FM Tuner]

Usable Sensitivity 11.3 dBf (1.0 µV/75 Ω) 50 dB Quieting Sensitivity 16.3 dBf (1.8 µV/75 Ω)

Alternate Channel Selectivity (400 kHz) 65 dB

Frequency Response 40 Hz to 15 000 Hz

Stereo Separation 35 dB

Capture Ratio 1.5 dB

[AM Tuner]

Sensitivity 20 µV

Selectivity 35 dB

Wow & Flutter 0.11% (WRMS)

Fast-Wind Time

Frequency Response (Dolby B NR OFF) 30 Hz to 16 000 Hz (Normal tape)

Signal-to-Noise Ratio (Normal tape)

Stereo Separation 40 dB

Grounding System Negative ground

Allowable Operating Temperature 0°C to +40°C (32°F to +104°F) Dimensions (W × H × D) Installation Size 182 mm x 52 mm x 150 mm (7-3/16" x 2-1/16" x 5-15/16")

(Dolby B NR ON) 65 dB

(Dolby B NR OFF) 56 dB

Panel Size 188 mm x 58 mm x 12 mm (7-7/16" x 2-5/16" x 1/2")

Mass 1.3 kg (2.9 lbs) (excluding accessories)

100 sec. (C-60)

Design and specifications are subject to change without notice.

1-2 (No.49845)

1.1 Safety Precautions

SECTION 1

Precautions

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.

(No.49845)1-3

SECTION 2

Disassembly method

2.1 Main body

2.1.1 Removing the front panel assembly (See Fig.1)

(1) Push the detach button in the lower left part of the front

panel assembly and remove the front panel assembly in the direction of the arrow.

2.1.2 Removing the bottom cover (See Fig.2)

• Prior to performing the following procedures, remove the front

panel assembly. (1) Turn the main body upside down. (2) Insert a screwdriver under the joints to release the two

joints a on the left side, two joints b on the right side and joint c on the back side of the main body, then remove the bottom cover from the main body.

CAUTION:

When releasing the joints using a screwdriver, do not damage the main board.

Front panel assembly

Detach button

Fig.1

Bottom cover

Joint b

Joint a

2.1.3 Removing the front chassis assembly (See Figs.3 and 4)

• Prior to performing the following procedures, remove the front

panel assembly and bottom cover. (1) Remove the two screws A on the both sides of the main

body. (See Fig.3.)

(2) Remove the two screws B on the front side of the main

body. (See Fig.4.)

(1) Release the two joints d and two joints e on the both sides

of the main body, then remove the front chassis assembly toward the front. (See Fig.3.)

Joint d

Front chassis assembly

Fig.3

Joint e

Joint a

Joint b

Joint c

Fig.2

Front chassis assembly

Fig.4

1-4 (No.49845)

2.1.4 Removing the heat sink

(See Fig.5)

• Prior to performing the following procedure, remove the front

panel assembly. (1) Remove the two screws C and screw D attaching the heat

sink on the left side of the main body, and remove the heat sink.

2.1.5 Removing the rear panel

(See Fig.6)

• Prior to performing the following procedure, remove the front

panel assembly and bottom cover. (1) Remove the two screws E, three screws F and three

screws G attaching the rear panel on the back side of the main body.

2.1.6 Removing the main board

(See Fig.7)

• Prior to performing the following procedures, remove the front

panel assembly, bottom cover, front chassis assembly, heat sink and rear panel. (1) Remove the two screws H attaching the main board on the

top chassis.

(2) Disconnect the connector CP401 on the main board from

the cassette mechanism assembly.

Heat sink

Fig.5

Rear bracket

Fig.6

Main board

CP401

Fig.7

(No.49845)1-5

2.1.7 Removing the cassette mechanism assembly (See Fig.8)

• Prior to performing the following procedures, remove the front

panel assembly, bottom cover, front chassis assembly, heat sink, rear panel and main board. (1) Disconnect the wire from the connector CN402 on the

mecha board.

(2) Disconnect the card wire from the connector CN403 on the

mecha board.

(3) Remove the four screws J attaching the cassette mecha-

nism assembly to the top chassis, take out the cassette mechanism assembly.

Cassette mechanism assembly

2.1.8 Removing the mecha board (See Fig.9)

• Prior to performing the following procedures, remove the front

panel assembly, bottom cover, front chassis assembly, heat sink, rear panel and main board. (1) Disconnect the wire from the connector CN402 on the

mecha board.

(2) Disconnect the card wire from the connector CN403 on the

mecha board. (3) Remove the screw K attaching the mecha board. (4) Bend the hook f in the direction of the arrow 1 and move

the mecha board in the direction of the arrow 2. (5) Remove the mecha board from the mecha bracket (L) of

the top chassis.

Mecha board

Top chassis

CN402

CN403

CN402

Fig.8

Mecha board

Fig.9

Top chassis

Hook f

Mecha bracket (L)

1-6 (No.49845)

2.1.9 Removing the front board (See Figs.10 to 12)

• Prior to performing the following procedures, remove the front

panel assembly. (1) Remove the four screws L attaching the rear cover on the

back side of the front panel assembly. (See Fig.10.)

(2) Release the nine joints g, the front panel assembly and

rear cover become separate. (See Fig.11.)

(3) Remove the front board from the front panel assembly.

(See Fig.12.)

Rear cover

Joint g

Rear cover

Front board

Joints g

Fig.10

Front panel assembly

Joint g

Joints g

Fig.11

Front panel assembly

Fig.12

(No.49845)1-7

2.2 Cassette mechanism assembly

REFERENCE:

Prior to performing the following procedures, turn the mode gear on the bottom of the body until the respective part comes to the EJECT position (Refer to Fig.1).

2.2.1 Removing the cassette guide (See Fig.2)

(1) Turn the mode gear to set to RVS play or subsequent

mode.

(2) Remove the cassette guide from the main chassis while re-

leasing each two joint tabs a in the direction of the arrow.

Mode gea

Fig.1

Cassette guide

2.2.2 Removing the load arm (See Fig.3)

(1) Remove the E-washer attaching the load arm. (2) Move the load arm in the direction of the arrow and release

the joint b on the cassette catch.

Load arm

E-washer

Tab a

Fig.2

Joint b

Fig.3

1-8 (No.49845)

2.2.3 Removing the cassette hanger assembly / cassette holder

(See Fig.4 to 7)

(1) Check the mode is set to EJECT. Push down the front part

of the cassette holder and move in the direction of the arrow to release the joint c.

(2) Move the rear part of the cassette hanger assembly in the

direction of the arrow to release it from the two joint bosses d.

(3) Release the holder stabilizer spring from the hooks e and

f, then pull out from the cassette hanger assembly.

(4) Bring up the rear side of the cassette hanger assembly to

release the joint g and h.

(5) Pull out the cassette catch from the cassette hanger as-

sembly.

Cassette holder assembly

Side bracket

Joints c

Cassette holder assembly

Fig.4

Boss d

Cassette hanger assembly

Boss d

Cassette stabilizer spring

Hook e

Cassette holder assembly

Hook g

Cassette hange

assembly

Hook f

Fig.5

Cassette hanger assembly

Hook h

Fig.6

Cassette hanger assembly

Cassette catch

Cassette holder assembly

Fig.7

(No.49845)1-9

2.2.4 Removing the side bracket assembly (See Fig.8 to 10)

(1) Remove the screw A attaching the side bracket assembly. (2) Detach the front side of the side bracket assembly upward

and pull out forward to release the joint i and j in the rear.

CAUTION:

When reassembling, make sure that the boss k of the main chassis is set in the notch of the load rack under the side bracket assembly. Do not reattach the load rack on the boss k.

CAUTION:

After reattaching the side bracket assembly, confirm operation.

Side bracket assembly

Joint i

Joint j

Side bracket assembly

Fig.8

Side bracket assembly

Joint i

Joint j

Load rack

Boss k

Fig.9

Boss k

1-10 (No.49845)

Fig.10

2.2.5 Removing the pinch arm (F) assembly

(See Fig.11 and 12)

(1) Remove the polywasher and pull out the pinch arm (F) as-

sembly.

(2) Remove the compulsion spring.

2.2.6 Removing the pinch arm (R) assembly

(See Fig.11 and 12)

(1) Remove the polywasher and pull out the pinch arm (R) as-

sembly.

2.2.7 Removing the slide chassis assembly

(See Fig.13 and 14)

REFERENCE:

It is not necessary to remove the head and the tape guide. (1) Move the slide chassis assembly in the direction of the ar-

row to release the two joints l and remove from the main chassis.

(2) Remove the rack link.

CAUTION:

When reassembling, first reattach the rack link, and next fit the boss m and hook n of the slide chassis assembly to the hole of the main chassis, and engage the two joints l.

Joint l

Slide chassis assembly

Fig.13

Head

Tape guide

Boss m

Rack link

Hook n

Polywasher

Compulsion spring

Pinch arm (R) assembly

Pinch arm (F) assembly

Fig.11

Pinch arm (F) assembly

Pinch arm (R) assembly

Polywashe

Fig.14

Polywasher

Fig.12

(No.49845)1-11

+ 23 hidden pages