JVC KW-XC939 Service Manual
MA041200310
SERVICE MANUAL
CD / CASSETTE RECEIVER
KW-XC939
Area suffix
EE --------- Russian Federation
TABLE OF CONTENTS
1 PRECAUTION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3
2 SPECIFIC SERVICE INSTRUCTIONS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-5
3 DISASSEMBLY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-6
4 ADJUSTMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-37
5 TROUBLESHOOTING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-41
COPYRIGHT © 2003 VICTOR COMPANY OF JAPAN, LIMITED
No.MA041
2003/10
SPECIFICATION
AUDIO AMPLIFIER SECTION
Maximum Power Output Front 45 W per channel
Rear 45 W per channel
Continuous Power Output (RMS) Front 17 W per channel into 4 Ω 40 Hz to 20 000 Hz at no more than 0.8%
total harmonic distortion.
Rear 17 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 to 8 Ω allowance)
Equalizer Control Range LOW ±12 dB (50 Hz, 80 Hz, 120 Hz)
MID ±12 dB (700 Hz, 1 kHz, 2 kHz)
HIGH ±12 dB (8 kHz, 12 kHz)
Frequency Response 40 Hz to 20 000 Hz
Signal-to-Noise Ratio 70 dB
Auxiliary input jack 3.5 mm dia. stereo mini jack
Line-Out Level/Impedance 2.0 V/20 kΩ load (full scale)
Output Impedance 1 kΩ
TUNER SECTION
Frequency Range FM 87.5 MHz to 108.0 MHz
AM 531 kHz to 1 602 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)
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
CD PLAYER SECTION
Type Compact disc player
Signal Detection System Non-contact optical pickup (semiconductor laser)
Number of channels 2 channels (stereo)
Frequency Response 5 Hz to 20 000 Hz
Dynamic Range 96 dB
Signal-to-Noise Ratio 98 dB
Wow and Flutter Less than measurable limit
MP3 decoding format MPEG1/2 Audio Layer 3
Max. Bit Rate 320 Kbps
CASSETTE DECK SECTION
Wow and Flutter 0.1 % (WRMS)
Fast-Wind Time 100 sec. (C-60)
Frequency Response 30 Hz to 16 000 Hz (Normal tape)
Signal-to-Noise Ratio (Normal tape)
Dolby B NR ON 65 dB
Dolby B NR OFF 56 dB
Stereo Separation 40 dB
Power Requirement Operating Voltage DC 14.4 V (11 V to 16 V allowance)
Grounding System Negative ground
Allowable Operating Temperature 0°C to +40°C
Dimensions (W × H × D) Installation Size 178 mm × 100 mm × 150 mm
Front Panel Size 170 mm × 96 mm × 20 mm
Mass 2.2 kg (excluding accessories)
Design and specifications are subject to change without notice.
65 dB
GENERAL
1-2 (No.MA041)
1.1 Safety Precautions
SECTION 1
PRECAUTION
!
!
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.
Please use enough caution not to see the beam directly or touch it in case of an
adjustment or operation check.
(No.MA041)1-3
1.2 Preventing static electricity
Electrostatic discharge (ESD), which occurs when static electricity stored in the body, fabric, etc. is discharged, can destroy the laser
diode in the traverse unit (optical pickup). Take care to prevent this when performing repairs.
1.2.1 Grounding to prevent damage by static electricity
Static electricity in the work area can destroy the optical pickup (laser dio de) in devices such as CD players.
Be careful to use proper grounding in the area where repairs are being performed.
(1) Ground the workbench
Ground the workbench by laying conductive material (such as a conductive sh eet) or an iron plate over it before placing the
traverse unit (optical pickup) on it.
(2) Ground yourself
Use an anti-static wrist strap to release any static electricity built up in your body.
(caption)
Anti-static wrist strap
1M
Conductive material
(conductive sheet) or iron plate
(3) Handling the optical pickup
• In order to maintain quality during transport and before instal lation, both sides of the laser di ode on the replacement optica l
pickup are shorted. After replacement, return the shorted parts to their original condition.
(Refer to the text.)
• Do not use a tester to check the condition of the laser diode in the optical pickup. The tester's internal power source can easily
destroy the laser diode.
1.3 Handling the traverse unit (optical pickup)
(1) Do not subject the traverse unit (optical pickup) to strong shocks, as it is a sensitive, complex unit.
(2) Cut off the shorted part of the flexible cable using nippers, etc. after replacing the optical pickup. For specific details, refer to the
replacement procedure in the text. Remove the anti-static pin when replacing the traverse unit. Be careful not to take too long a
time when attaching it to the connector.
(3) Handle the flexible cable carefully as it may break when subjected to strong force.
(4) It is not possible to adjust the semi-fixed resistor that adjusts the laser power. Do not turn it.
1.4 Attention when traverse unit is decomposed *Please refer to "Disassembly method" in the text for the CD pickup unit.
• Apply solder to the short land before the flexible wire is disconnected from the connector on the CD pickup unit.
(If the flexible wire is disconnected without applying solder, the CD pickup may be destroyed by static electricity.)
• In the assembly, be sure to remove solder from the short land after connecting the flexible wire.
Short-circuit point
(Soldering)
1-4 (No.MA041)
Short-circuit point
Flexible wire
Pickup
Pickup
SECTION 2
SPECIFIC SERVICE INSTRUCTIONS
This service manual does not describe SPECIFIC SERVICE INSTRUCTIONS.
(No.MA041)1-5
SECTION 3
DISASSEMBLY
3.1 Main body
3.1.1 Removing the front panel assembly
(See Fig.1, 2)
(1) From the both side of the main body, remove the four screws
A attaching the front panel assembly. (See Figs.1, 2)
(2) Release the four joints a using a screwdriver, then remove
the front panel assembly toward the front. (See Figs.1, 2)
Front panel assembly
A
Joints a
A
Fig.1
Front panel assembly
A
Joints a
3.1.2 Removing the rear bracket
(See Figs.3)
• Prior to performing the following procedure, remove the front
panel assembly as required.
(1) From the back side of the main body, remove the ten
screws B, screw C and screw D attaching the rear bracket.
(2) Take out the rear bracket.
3.1.3 Removing the heat sink
(See Fig.4)
• Prior to performing the following procedure, remove the front
panel assembly as required.
(1) From the left side of the main body, remove the two screws
E and three screws F attaching the heat sink.
B
B
B
A
Fig.2
BC
D
Rear braket
Fig.3
Heat sink
FFE
1-6 (No.MA041)
F
Fig.4
3.1.4 Removing the top chassis assembly and bottom
chassis assembly
(See Fig.5 to 7)
• Prior to performing the following procedures, remove the front
panel assembly, rear bracket and heat sink.
(1) From the back side of the main body, disconnect the card
wire from the connector CN702
top chassis assembly. (See Fig.5)
(2) From the both side of the main body, remove the three
screws G attaching the bottom chassis assembly. (See
Figs.6, 7)
(3) Release the four joints b using a screwdriver, and then re-
move the top chassis assembly upward from the bottom
chassis assembly. (See Figs.6, 7)
on the main board in the
CN702
Card wire Main board
Fig.5
Top chassis assembly
G
3.1.5 Removing the main board
(See Fig.8)
• Prior to performing the following procedures, remove the front
panel assembly, rear bracket, heat sink, top chassis assembly
and bottom chassis assembly.
(1) From the bottom side of the top chassis assembly, remove
the three screws H attaching the main board.
(2) Disconnect the connector CN501
take out the main board from the top chassis assembly.
Reference:
• When attaching the main board, joint the hole of the main
board in joint c of the top chassis assembly.
on the main board, and
Bottom chassis assemblyGJoints b
Fig.6
Top chassis assembly
Joints b
Top chassis assembly
Bottom chassis assembly
Fig.7
Main board
H
G
CN601
H
H
Joints c
Fig.8
(No.MA041)1-7
3.1.6 Removing the CD mecha control board
(See Fig.9)
• Prior to performing the following procedures, remove the fro nt
panel assembly, rear bracket, heat sink, top chassis assembly
and main board.
(1) From the top side of top chassis assembl y , disconnect the
card wire from the connector CN601
trol board.
(2) Remove the five screws J attaching the CD mecha control
board, and release the joint d and joint e from the top chassis assembly.
on the CD mecha con-
Joint e
Card
wire
J
Joint d
3.1.7 Removing the CD mechanism assembly
(See Fig.10)
• Prior to performing the following procedures, remove the fro nt
panel assembly, rear bracket, heat sink, top chassis assembly,
main board and CD mecha control board.
(1) Remove the three screws K attaching the CD mechanism
assembly to the top chassis assembly.
Reference:
• When attaching the CD mechanism assembly, joint the hole
of the CD mechanism assembly in boss f and boss g of the
top chassis assembly.
CN601
CD mecha control board
CD mechanism assembly
K
J
Fig.9
K
Fig.10
Top chassis assembly
K
Boss gBoss f
Top chassis assembly
1-8 (No.MA041)
3.1.8 Removing the changer control board
(See Fig.11, 12)
• Prior to performing the following procedures, remove the front
panel assembly, rear bracket, heat sink, top chassis assembly
and bottom chassis assembly.
(1) m the connector CN972
Fig.11)
(2) From the top side of the bottom chassis assembly, remove
the two screws L attaching the changer control board. (See
Fig.12)
Reference:
• When attaching the changer control board, joint the hole of
the changer control board in joints h of the bottom chassis
assembly.
on the changer control board. (See
Changer control board
Bottom chassis assembly
Cassette mechanism assembly
Bottom chassis assembly
CN972
Card wire
Fig.11
3.1.9 Removing the mecha co ntr ol board
(See Fig.13)
• Prior to performing the following procedures, remove the front
panel assembly, rear bracket, heat sink, bottom chassis assembly and changer control board.
(1) From the back side of the bottom chassis assembly, re-
move the screw M attaching the mecha control board, and
release the joints i from the bottom chassis assembly.
(2) Disconnect the wire from the connector CN402
card wire from the connector CN403
board.
Reference:
• When attaching the mecha control board, joint the hole o f
the mecha control board in joints i of the bottom chassis assembly.
on the mecha control
and the
L
Changer control board
Fig.12
CN403CN402
Joint h
Joint i
M
Top chassis assembly Mecha control board
Fig.13
L
(No.MA041)1-9
3.1.10 Removing the cassette mechanism assembly
(See Fig.14)
• Prior to performing the following procedures, remove the fro nt
panel assembly, rear bracket, heat sink, bottom chassis assembly, changer control board and mecha control board.
(1) From the bottom side of the bottom chassis assembly, re-
move the four screws N attaching the cassette mechanism
assembly to the bottom chassis assembly.
N
3.1.11 Removing the LCD board
(See Fig.15)
• Prior to performing the following procedures, remove the fro nt
panel assembly.
(1) From the back side of front panel assembly, remove the
twelve screws P attaching the LCD board, and the n turn
over the LCD board.
(2) From the reverse side of LCD board, remove the solders
from the soldered points j attaching the wire.
3.1.12 Removing the switch board
(See Fig.16)
• Prior to performing the following procedures, remove the fro nt
panel assembly.
(1) From the back side of front panel assembly, remove the
five screws Q attaching the switch board.
(2) Release the claws k attaching the switch board, and then
turn over the switch board.
(3) From the reverse side of switch board, remove the solders
from the soldered points m attaching the wire.
N
Cassette mechanism assembly
Fig.14
Front panel assembly
P
LCD board
Fig.15
Front panel assembly
Bottom chassis assembly
PP
P
Solder points j
Solder points m
1-10 (No.MA041)
Q
Claws k
Fig.16
Q
Switch board
3.2 CD Mechanism section
A
3.2.1 Removing the top cover
(See Figs.1 and 2)
(1) Remove the four screws A on the both side of the body.
(2) Lift the front side of the top cover and move the top cover
backward to release the two joints a.
Top cover
Joints a
A
Joints a
A
Fig.1
Fig.2
Top cover
(No.MA041)1-11
3.2.2 Removing the connector board
(See Figs.3 to 5)
CAUTION:
Before disconnecting the flexible wire from the pickup, solder
the short-circuit point on the pickup. No observance of this instruction may cause damage of the pickup.
(1) Remove the screw B fixing the connector board.
(2) Solder the short-circuit point on the pickup.
(3) Disconnect the flexible wire from the pickup.
(4) Move the connector board in the direction of the arrow to
release the two joints b.
(5) Unsolder the wires on the connector board if necessary.
CAUTION:
Unsolder the short-circuit point after reassembling.
B
Connector board
Flexible wire
Wires
Joints b
Short-circuit point
Fig.3
Short-circuit point
(Soldering)
Pickup
Flexible wire
Frame
Pickup
Fig.4
B
Connector board
Fig.5
1-12 (No.MA041)
3.2.3 Removing the DET switch
(See Figs.6 and 7)
(1) Extend the two tabs c of the feed sw. holder and pull out
the switch.
(2) Unsolder the DET switch wire if necessary.
DET
switch
Connector
board
Pickup
Fig.6
DET switch
Tab c
Tab c
DET switch wire
Feed sw. holder
Fig.7
(No.MA041)1-13
3.2.4 Removing the chassis unit
r
(See Figs.8 and 9)
• Prior to performing the following procedure, remove the top
cover and connector board.
(1) Remove the two suspension springs (L) and (R) attaching
the chassis unit to the frame.
CAUTION:
• The shape of the suspension spring (L) and (R) are different. Handle them with care.
• When reassembling, make sure that the three shafts
on the underside of the chassis unit are inserted to the
dampers certainly.
Suspension spring (R)
Chassis unit
Suspension spring (L)
Frame
Suspension spring (R)
Chassis unit
Shafts
Damper
Damper
Suspension spring (L)
Fig.8
Shaft
Dampe
Frame
Fig.9
1-14 (No.MA041)
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