JVC UXG-3, UXG-4 Service manual
SERVICE MANUAL
MICRO COMPONENT SYSTEM
MB42920057
UX-G3, UX-G4
UX-G3
Area suffix
US ------------------------ Singapore
UB ---------------------- Hong Kong
UP ----------------------------- Korea
UT ---------------------------- Taiwan
UW ----------- Brazil,Mexico,Peru
UY ------------------------- Argentina
UX-G4
Area suffix
A ------------------------ Australia
US ------------------------ Singapore
UB ---------------------- Hong Kong
UT ---------------------------- Taiwan
UW ----------- Brazil,Mexico,Peru
CA-UXG3 SP-UXG3SP-UXG3
CA-UXG4 SP-UXG4SP-UXG4
Lead free solder used in the board (material : Sn-Ag-Cu, melting point : 219 Centigrade)
TABLE OF CONTENTS
1 PRECAUTION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3
2 SPECIFIC SERVICE INSTRUCTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4
3 DISASSEMBLY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-5
4 ADJUSTMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-16
5 TROUBLESHOOTING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-19
COPYRIGHT © 2005 Victor Company of Japan, Limited
No.MB429
2005/7
SPECIFICATION
Amplifier Section Output Power 25 W per channel, min. RMS, driven into 4 Ω at 1 kHz with no more
than 10% total harmonic distortion (IEC268-3).
Audio input sensitivity/Impedance (at 1 kHz) AUX: 500 mV/50 kΩ
Speakers Impedance 4 Ω - 16 Ω
Tuner FM tuning range 50 kHz intervals 87.50 MHz-108.00 MHz
100 kHz intervals 87.5 MHz-108.0 MHz
AM tuning range 9 kHz intervals 531 kHz-1 710 kHz
10 kHz intervals 530 kHz-1 710 kHz
CD player Dynamic range 85 dB
Signal-to-noise ratio 85 dB
Wow and flutter Immeasurable
Cassette deck Wow and flutter 100 Hz - 10 000 Hz
Wow and flutter 0.35% (WRMS)
General Power requirement AC 110 V-127 V / AC 220 V-240 V (adjustable with the voltage selec-
tor), 50Hz / 60Hz
Power consumption 52 W (at operation)
3.0 W (on standby)
Dimensions (W/H/D) (approx.) 152 mm × 233 mm × 331 mm
Mass (approx.) 4.7 kg
Speaker Section Type Full range, bass-reflex type
Speakers 10 cm cone × 1
Power handling capacity 25 W
Impedance 4 Ω
Frequency range 100 Hz - 15 kHz
Dimensions (W/H/D) (approx.) 152 mm × 233 mm × 188 mm
Mass (approx.) 1.8 kg each
Design and specifications are subject to change without notice.
1-2 (No.MB429)
SECTION 1
PRECAUTION
1.1 Safety Precautions
(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) Alterations 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 manufacturers warranty 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 reassembling.
(5) Leakage shock hazard testing
After reassembling 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, 1,000Ω per volt or more sensitivity
in the following manner. Connect a 1,500Ω 10W resistor
paralleled by a 0.15µF AC-type capacitor between an ex-
posed 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 measure the AC voltage across
the resistor. 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.).
AC VOLTMETER
(Having 1000
ohms/volts,
or more sensitivity)
0.15 F AC TYPE
Place this
probe on
1500 10W
Good earth ground
1.2 Warning
(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 must 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.
1.3 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.
1.4 Critical parts for safety
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. When replacing them, be sure to use the parts of the
same type and rating as specified by the manufacturer.
(This regulation dose not Except the J and C version)
each exposed
metal part.
(No.MB429)1-3
SECTION 2
SPECIFIC SERVICE INSTRUCTIONS
This service manual does not describe SPECIFIC SERVICE INSTRUCTIONS.
1-4 (No.MB429)
SECTION 3
DISASSEMBLY
3.1 Main body
3.1.1 Removing the front panel assembly
(See Fig.1 to 6)
(1) From the back of the body, remove the two screws A, the
two screws B and the two screws D attaching the front pan-
el assembly.
(2) Remove the six screws E on both sides of the body.
(3) Remove the screw F on the bottom of the body.
(4) Move the front panel assembly in the direction of the arrow
and remove. Disconnect the wire from connector CN102
CN402, CON801 on the main board.
Caution:
When reassembling the front panel assembly, fit the right and
left joints a to the notch.
A
,
CD mechanism assembly
D
Front panelh assembly
E
B
Rear cover assembly
Fig.1
CD mechanism assembly
Rear cover assembly
Fig.2
(No.MB429)1-5
CD mechanism assembly
Rear panel assembly
Fig.3
Front panel assembly
F
CD mechanism assembly
Joint a
Front panelh assembly
E
Front panel assembly
Rear cover assembly
Fig.5
Rear panel assembly
Fig.4
Front panel assembly
CD mechanism assembly
CN102
Main board
CN402
Rear cover assembly
CON801
1-6 (No.MB429)
Fig.6
3.1.2 Removing the main board
(See Fig.7, 8)
• Prior to performing the following procedure, remove the front
panel assembly.
(1) Disconnect the wire from all connectors on the main board.
(2) Disconnect the wire from the two connectors on the cas-
sette mechanism assembly.
(3) Release the two bands attaching the wire to the main
board.
(4) Remove the two screws G from the front panel assembly.
Release the joint b.
Front panel assembly
CD mechanism assembly
CN481
Main board
CN203
CN303
CN602
CD mechanism assembly
CN103
CN102
CN401
CN301
CN603
CD mechanism assembly
Joint b
Main board
Fig.7
G
Front panel assembly
Band
Fig.8
(No.MB429)1-7
3.1.3 Removing the CD mechanism assembly
(See Fig.9, 10)
• Prior to performing the following procedure, remove the front
panel assembly and the main board.
(1) Remove the three bands attaching the wire.
(2) Disconnect the connector from the CD door switch. Discon-
nect the wire from connector CN603
mechanism board.
(3) Disconnect the wire soldered on the CD mechanism board.
(4) Remove the three screws H attaching the CD mechanism
assembly.
(5) Release the joints d to remove the CD mechanism assem-
bly from the front panel assembly.
and CN606 on the CD
Front panel assembly
H
Band
H
CD door switch
CD mechanism assembly
Band
Joint d
Band
CD mechanism board
Joint d
H
CN603
Fig.9
CD mechanism assembly
CN606
1-8 (No.MB429)
CN603,CN606
band
wire
Front panel assembly
Fig.10
3.1.4 Removing the CD mechanism assembly
(See Fig.11 to 13)
• Prior to performing the following procedure, remove the front
panel assembly, the main board and the CD mechanism assembly.
Caution:
Before disconnecting the card wire from connector CN601
the CD mechanism board and from CD pickup board, solder
the short-circuit point on the CD pickup board. If you do not follow this instruction, the pickup may be damaged.
(1) Disconnect the wire from connector on the CD motor
board.
(2) Remove the four screws J attaching the CD mechanism
board.
(3) Move the CD mechanism board temporarily as shown in
Fig.12.
(4) Remove the screw K attaching the wire to the CD mecha-
nism.
(5) Solder the short-circuit point on the CD pickup board.
(6) Disconnect the card wire from connector CN601
mechanism board.
Caution:
Make sure to unsolder the short-circuit point after reconnecting
the card wire to the CD pickup board and to connector CN601
on the CD mechanism board.
CD mechanism assembly
on
on the CD
CD mechanism board
CN601
wire
Cord wire
Short-circuit point
K
CD motor board
CD mechanism assembly
Fig.12
Unsolder
Short-circuit point
J
J
CD mechanism board
CN601
Wire
Fig.11
Card wire
CD pickup board
Fig.13
(No.MB429)1-9
3.1.5 Removing the CD mechanism
A
(See Fig.14)
• Prior to performing the following procedure, remove the front
panel assembly, the main board, the CD mechanism assembly
and the CD mechanism board.
(1) Remove the four screws M attaching the CD mechanism.
M
CD mechanism
3.1.6 Removing the headphone board/ AUX board
(See Fig.15)
• Prior to performing the following procedure, remove the front
panel assembly, the main board and the CD mechanism assembly.
(1) Remove the screw N attaching the headphone board.
(2) Remove the screw P attaching the AUX board.
M
P
CD mechanism assembly
Fig.14
N
1-10 (No.MB429)
UX board
Head phones board
Front panel assembly
Fig.15
3.1.7 Remove the LCD board
(See Fig.16, 17)
• Prior to performing the following procedure, remove the front
panel assembly, the main board and the CD mechanism assembly.
(1) From the front panel, pull out the volume knob and remove
the nut and the washer.
(2) Remove the twelve screws Q attaching the LCD board.
Volume konb
Front panel assembly
Nut
Washer
Q
Q
Fig.16
LCD board
Q
Q
Fig.17
Front panel assembly
(No.MB429)1-11
3.1.8 Removing the cassette mechanism assembly
(See Fig.18, 19)
• Prior to performing the following procedure, remove the front
panel assembly and the main board.
(1) Push 'PUSH OPEN' on the front panel to open the cassette
door.
(2) Remove the screw R attaching the bracket of the cassette
mechanism assembly.
(3) Remove the two screws T and the two screws U attaching
the cassette mechanism assembly.
PUSH OPEN
Cassette door
Front panel assembly
Fig.18
U
R
Front panel assembly
U
1-12 (No.MB429)
Bracket
TT
Cassette mechaanism assembly
Fig.19
3.1.9 Removing the heat sink/power board
Y
(See Fig.20 to 25)
• Prior to performing the following procedure, remove the front
panel assembly.
(1) Remove the four screws Y attaching the holder in the pow-
er unit section.
(2) Move the power unit section with the wire from the rear cov-
er temporarily. If necessary, release the band and unsolder
the wire on the power board.
(3) Remove the four screws A' and the two screws B' attach-
ing the holder.
(4) Remove the three bands on the wire extending from the
power board (part e). Move the holder in the direction of the
arrow to detach from the joint f.
(5) Remove the four screws D' and screw E' attaching the heat
sink.
Y
Power unit section
Y
Y
Rear cover
Rear cover
Power trnsfomer assembly
Fig.20
Power unit section
Fig.21
(No.MB429)1-13
A
Heat sink
k
Holder
D'
Heat sink
A'
e Band
E'
'
e Band
Power board
Fig.22
Heat sink
Power board
Fig.24
B'
Power board
B'
D'
Heat sin
Joint f
Holder
e
Band
Fig.23
Power board
D'
Fig.25
1-14 (No.MB429)
3.1.10 Removing the power transformer assembly
(See Fig.26, 27)
• Prior to performing the following procedure, remove the front
panel assembly and the power unit section.
(1) Remove the four screws F' attaching the power transform-
er assembly. The bracket comes off at the bottom of the
rear cover.
(2) Remove the screw G' attaching the power cord folder.
(3) Remove the two screws H' attaching the AC connect
board.
3.1.11 Removing the FM-ANT board
(See Fig.26, 27)
• Prior to performing the following procedure, remove the front
panel assembly and the power unit section.
(1) Remove the screw J' on the rear cover assembly.
(2) Unsolder the FM-ANT wire on the FM-ANT board.
F'
Power trnsfomer assembly
F'
FM-ANT board
J'
Rear cover
Fig.26
Rear cover
AC connect board
Power cord folder
G'
Fig.27
H'
H'
(No.MB429)1-15
SECTION 4
ADJUSTMENT
4.1 Measuring instructions required for adjustment
• AM signal generator
• FM signal generator
• Inter medicate frequency sweep generator
• FM stereo signal generator
• Low-frequensy oscillator (osillation frequency 50 Hz - 20 kHz, 0 dB output with 600 Ω impedance)
• Attenuator (600 Ω impedance)
• Electoronic voltmeter
• Distortion meter
• Torque gauge (cassette for CTG-N)
• Wow & flutter meter
• Frequency counter meter
4.2 Test tape
• Playback tape
VT712 (tape speed, wow flutter)
VT724 (reference level)
VT703L (head azimuth)
VT738 (frequency responce)
• Recording tape
AC225 (type I)
• Power supply voltage
AC220V - 240V 50Hz
4.3 Measuring instruments
• Radio section
FM : 1 kHz, 22.5kHz deviation
FM stereo : 1 kHz, 67.5 kHz deviation, pilot signal 7.5 kHz
AM : 1 kHz, 30% modulation
Reference output : 0 dB (1 V) 4 Ω
Headphone output : -10 dB (0.1V) 32 Ω
4.4 Amplifier section
• Reference output : Speaker output 0 dB (1 V) / 4 Ω
Headphone output -10 dB (0.1 V) / 32 oh
4.5 CD section
• Test disc : CTS-1000 (JVC)
TCD-731R (A-BEX)
TCD-712R (A-BEX)
TCD-785 (A-BEX)
1-16 (No.MB429)
4.6 Cassette amplifier section
Item Measuring condition Check and adjustment procedure Standard value Adjusting part
Head azimuth
adjustment
Tape speed
and
wow/flutter
check and
adjustment
PB frequency
responce
check
Bias frequency
check
REC and PB
frequency
responce
adjustment
Test tape : VT703
Signal output terminal :
PHONES
(with 32 ohm load)
Test tape : VT712
Signal output terminal :
PHONES
(with 32 ohm load)
Test tape : VT738
Signal output terminal :
PHONES
(with 32 ohm load)
Test tape : normal
Signal output terminal :
Casssette R/P head
Test tape : AC225
Signal input : FM 22.5
dev, 60dBu with
emphasis
Signal output terminal :
PHONES
(with 32 ohm load)
4.7 Tuner section
1.Plyback the test tape VT703.
2.Adjust the head azimuth adjusting screw
so that the phase difference between the
R and L channels is minimized at an
output level that is within +/- 2dB of the
maximum output level.
After this adjustment, lock the head
azimuth adjusting screw with screw
sealant to cover more than a half of the
screw head.
3.When the head azimuth is maladjusted,
correct it with the head azimuth adjusting
screw.
1.Plyback the test tape VT712 by the end
of position.
2.Connect a frequency counter and check
that it reads between 2940 and 3090 Hz.
If not, adjust the frequenct with the motor
semifixed resistor.
3.Check that the wow / flutter is 0.38%
(unweighted).
Playback the test tape VT738 while confirming that deviation between the 1 kHz
signal and 8 kHz signal should be
0 (+3 to -6) dB.
Set the TUNER or CD function and with
TAPE to record. Check to see if the
frequency at the measuring point (R335 or
R336) is 60 kHz +/-1 kHz if not adjust T360
until the frequency counter indicates
60 kHz +/- 1 kHz.
At TUNER, set the BAND to the FM
position, and record the reference 1 kHz
signal and 8 kHz signal altemately
repeatedly. While playing back the
recorded signal differ from that of the 1 kHz
signal by within 0 (+3 to 6) dB.
Output level :
within +/-2dB
of maximum
output level
Phase defference
L and R channels:
minimum
2940 to 3090 Hz
within 0.38%
(unweighted)
deviation between
1 kHz and 8 kHz :
0 (+3 to -6) dB.
Level difference
between REC and
PB : within 0
(+3 to 6) dB
Head azimuth
adjusting screw
(to be used only
after head replacement)
Tape speed :
motor semifixed
resistor
check only
L203
Item Measuring condition Check and adjustment procedure Standard value Adjusting part
AM IF
adjustment
AM tracking
adjustment
Tuner 114 kHz
filter the waves
adjustment
Signal input : Loop
antenna
Signal output : IC201
pin 18
Signal input : Loop
antenna
Signal output : PHONES
(with 32 ohm load)
Signal input : IC101
pin 19
Signal output : IC101
pin 18
1.Set the intermediate frequency sweep
generator to AM 450 kHz.
2.Adjust the T203 from maximum and
center output.
1.Set the TUNER at 522 kHz adjust T201
until the test pin of R245 voltage at
1.55 V +/- 0.1 V.
2.Set the TUNER at 1629 kHz, check the
pin of R245 voltage at 8.4 V +/- 6V.
3.Set the TUNER ang S/G at 612 kHz,
adjust T202 for maximum output.
4.Set the TUNER and S/G at 1404 kHz,
adjust T201 for maximum output.
5.Repwat the above step 3 and 4.
1.Set the unit in standby mode. Input 114
kHz signal to IC101 pin 19.
2.Adjust the T204 for output voltage
minimum.
T203
T201
R245
TC201
T204
(No.MB429)1-17
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