JVC CD/Cassette Receiver KW-XC939 User manual

SERVICE MANUAL
COPYRIGHT © 2003 VICTOR COMPANY OF JAPAN, LIMITED No.MA041
2003/10
CD / CASSETTE RECEIVER
MA041200310 KW-XC939
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
Area suffix
EE --------- Russian Federation

1-2 (No.MA041)
SPECIFICATION
Design and specifications are subject to change without notice.
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 Ω40 Hz to 20 000 Hz at no more than 0.8%
total harmonic distortion.
Rear 17 W per channel into 4 Ω40 Hz to 20 000 Hz at no more than 0.8%
total harmonic distortion.
Load Impedance 4 Ω(4 to 8 Ωallowance)
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 kΩload (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) 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
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
GENERAL
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)

(No.MA041)1-3
SECTION 1
PRECAUTION
1.1 Safety 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.
!Please use enough caution not to see the beam directly or touch it in case of an
adjustment or operation check.

1-4 (No.MA041)
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 diode) 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 sheet) 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.
(3) Handling the optical pickup
• In order to maintain quality during transport and before installation, both sides of the laser diode on the replacement optical
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.
1M
(caption)
Anti-static wrist strap
Conductive material
(conductive sheet) or iron plate
Pickup
Short-circuit point
(Soldering)
Flexible wire
Pickup
Short-circuit point

(No.MA041)1-5
SECTION 2
SPECIFIC SERVICE INSTRUCTIONS
This service manual does not describe SPECIFIC SERVICE INSTRUCTIONS.

1-6 (No.MA041)
SECTION 3
DISASSEMBLY
3.1 Main body
3.1.1 Removing the front panel assembly
(See Fig.1, 2)
(1) From thebothside of themainbody,remove thefourscrews
Aattaching the front panel assembly. (See Figs.1, 2)
(2) Release the four joints ausing a screwdriver, then remove
the front panel assembly toward the front. (See Figs.1, 2)
Fig.1
Fig.2
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 Cand screw Dattaching the rear bracket.
(2) Take out the rear bracket.
Fig.3
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
Eand three screws Fattaching the heat sink.
Fig.4
A
A
Front panel assembly
Joints a
A
A
Joints a
Front panel assembly
BD
B
B
Rear braket
BC
FFE
F
Heat sink

(No.MA041)1-7
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 on the main board in the
top chassis assembly. (See Fig.5)
(2) From the both side of the main body, remove the three
screws Gattaching the bottom chassis assembly. (See
Figs.6, 7)
(3) Release the four joints busing a screwdriver, and then re-
move the top chassis assembly upward from the bottom
chassis assembly. (See Figs.6, 7) Fig.5
Fig.6
Fig.7
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 Hattaching the main board.
(2) Disconnect the connector CN501 on the main board, and
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 cof the top chassis assembly.
Fig.8
CN702
Card wire Main board
Top chassis assembly
Bottom chassis assembly
G
Joints b
G
Top chassis assembly
Bottom chassis assembly
Joints b
G
CN601
Main board
H
H
H
Top chassis assembly
Joints c

1-8 (No.MA041)
3.1.6 Removing the CD mecha control board
(See Fig.9)
• Prior to performing the following procedures, remove the front
panel assembly, rear bracket, heat sink, top chassis assembly
and main board.
(1) From the top side of top chassis assembly, disconnect the
card wire from the connector CN601 on the CD mecha con-
trol board.
(2) Remove the five screws Jattaching the CD mecha control
board, and release the joint dand joint efrom the top chas-
sis assembly.
Fig.9
3.1.7 Removing the CD mechanism assembly
(See Fig.10)
• Prior to performing the following procedures, remove the front
panel assembly, rear bracket, heat sink, top chassis assembly,
main board and CD mecha control board.
(1) Remove the three screws Kattaching 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 fand boss gof the
top chassis assembly.
Fig.10
J
J
CD mecha control board
Joint d
Joint e
Top chassis assembly
CN601
Card
wire
K
KK
CD mechanism assembly
Boss gBoss f
Top chassis assembly

(No.MA041)1-9
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 on the changer control board. (See
Fig.11)
(2) From the top side of the bottom chassis assembly, remove
the two screws Lattaching the changer control board. (See
Fig.12)
Reference:
• When attaching the changer control board, joint the hole of
the changer control board in joints hof the bottom chassis
assembly.
Fig.11
Fig.12
3.1.9 Removing the mecha control board
(See Fig.13)
• Prior to performing the following procedures, remove the front
panel assembly, rear bracket, heat sink, bottom chassis as-
sembly and changer control board.
(1) From the back side of the bottom chassis assembly, re-
move the screw Mattaching the mecha control board, and
release the joints ifrom the bottom chassis assembly.
(2) Disconnect the wire from the connector CN402 and the
card wire from the connector CN403 on the mecha control
board.
Reference:
• When attaching the mecha control board, joint the hole of
the mecha control board in joints iof the bottom chassis as-
sembly.
Fig.13
CN972
Card wire
Changer control board
Bottom chassis assembly
L
Changer control board
Bottom chassis assembly
L
Joint h
Cassette mechanism assembly
M
Top chassis assembly Mecha control board
Joint i
CN403CN402

1-10 (No.MA041)
3.1.10 Removing the cassette mechanism assembly
(See Fig.14)
• Prior to performing the following procedures, remove the front
panel assembly, rear bracket, heat sink, bottom chassis as-
sembly, changer control board and mecha control board.
(1) From the bottom side of the bottom chassis assembly, re-
move the four screws Nattaching the cassette mechanism
assembly to the bottom chassis assembly.
Fig.14
3.1.11 Removing the LCD board
(See Fig.15)
• Prior to performing the following procedures, remove the front
panel assembly.
(1) From the back side of front panel assembly, remove the
twelve screws Pattaching the LCD board, and then turn
over the LCD board.
(2) From the reverse side of LCD board, remove the solders
from the soldered points jattaching the wire.
Fig.15
3.1.12 Removing the switch board
(See Fig.16)
• Prior to performing the following procedures, remove the front
panel assembly.
(1) From the back side of front panel assembly, remove the
five screws Qattaching the switch board.
(2) Release the claws kattaching 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 mattaching the wire.
Fig.16
N
Cassette mechanism assembly
Bottom chassis assembly
N
Front panel assembly
LCD board Solder points j
PP
PP
Q
Front panel assembly
Switch board
Q
Claws k
Solder points m