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SERVICE MANUAL
COPYRIGHT © 2003 VICTOR COMPANY OF JAPAN, LIMITED
No.MB141
2003/12
DVD DIGITAL THEATER SYSTEM
MB141
2003
12
TH-A25
TABLE OF CONTENTS
1
PRECAUTION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3
2
SPECIFIC SERVICE INSTRUCTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-6
3
DISASSEMBLY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-7
4
ADJUSTMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-13
5
TROUBLESHOOTING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-14
Area suffix
J ----------------------------- U.S.A.
C -------------------------- Canada
SOUND
VOLUME
SOURCE
STANDBY
STANDBY/ON
DVD DIGIT
AL CINEMA SYSTEM TH-A25


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1-2 (No.MB141)
SPECIFICATION
Designs & specifications are subject to change without notice.
Center unit (XV-THA25)
Amplifier Front/Center/Rear 30 W per channel, min. RMS, driven into 6
at 1 kHz, with no more than 10% total harmonic distortion
Subwoofer
55 W, min. RMS, driven into 3
at 100 Hz, with no more than 10% total harmonic distortion
Audio
Audio input sensitivity/Impedance (at 1 kHz)
Analog input
AUX ("AUDIO IN")
500 mV/47 k
Signal-to-Noise Ratio
68 dB
Digital input*
DIGITAL IN (OPTICAL)
-24 dBm to -14.5 dBm (700 nm ±50 nm)
* Corresponding to Linear PCM, Dolby Digital, and DTS Digital Surround (with sampling frequency-32 kHz, 44.1 kHz, 48
kHz)
Video
Color System
NTSC
Horizontal Resolution
480 lines
Output Level
VIDEO OUT (Composite) 1.0 V(p-p)/75
S-VIDEO
(Y):1.0 V(p-p)/75
(C):0.286 V(p-p)/75
COMPONENT
VIDEO OUT
Y
1.0 V(p-p)/75
PB/PR
0.7 V(p-p)/75
Tuner
Tuning Range
FM
87.50 MHz - 108.00 MHz
AM
530 kHz - 1 710 kHz
Usable Sensitivity FM
8.0 dBf (0.9
µV/75 )
AM loop antenna
650
µV/m
General Readable Discs
DVD VIDEO, Video CD, Super Video CD, Audio CD, CD-R/RW (Audio CD,
Video CD, Super Video CD, MP3, JPEG), DVD-R/RW (Video format)
Power Requirements
AC 120 V , 60 Hz
Power Consumption
110 W (at operation) 2 W (in standby mode)
Dimensions (W
× H × D)
360 mm
× 65 mm × 404 mm (14 3/16 in. × 2 9/16 in. × 15 15/16 in.)
Mass
6.3 kg (13.9 lbs)
Subwoofer (SP-WA25)
Speaker
15 cm (5 15/16 in.) Bass-reflex, magnetically shielded
Power Handling Capacity
55 W
Impedance
3
(min)
Frequency Range
30 Hz to 200 Hz
Dimensions (W
× H × D)
210 mm
× 382 mm × 338 mm (8 5/16 in. × 15 1/16 in. × 13 5/16 in.)
Mass
6 kg (13.3 lbs)
Satellite Speakers (SP-XTHA25)
Speaker
8 cm (3 3/16 in.) Bass-reflex, magnetically shielded
Power Handling Capacity
30 W
Impedance
6
(min)
Frequency Range
80 Hz to 20 kHz
Dimensions (W
× H × D)
105 mm
× 114 mm × 116 mm (4 3/16 in. × 4 1/2 in. × 4 5/8 in.)
Mass
640 g (1.5 lbs)


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(No.MB141)1-3
SECTION 1
PRECAUTION
1.1
Safety Precautions
(1) This design of this product contains special hardware and
many circuits and components specially for safety purpos-
es. 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 per-
formed 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 characteris-
tics are often not evident from visual inspection nor can the
protection afforded by them necessarily be obtained by us-
ing replacement components rated for higher voltage, watt-
age, etc. Replacement parts which
have these special
safety characteristics are identified in the Parts List of Ser-
vice 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 charac-
teristics 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 reassem-
bling.
(5) Leakage shock hazard testing
After reassembling the product, always perform an isola-
tion check on the exposed metal parts of the product (an-
tenna 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, particular-
ly any exposed metal part having a return path to the
chassis, to a known good earth ground. Any leakage cur-
rent 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, 1,000
per volt or more sensitivity
in the following manner. Connect a 1,500
10W resistor
paralleled by a 0.15
µF 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.).
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 pre-
forming 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)
Good earth ground
Place this
probe on
each exposed
metal part.
AC VOLTMETER
(Having 1000
ohms/volts,
or more sensitivity)
1500
10W
0.15 F AC TYPE


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1-4 (No.MB141)
1.5
Preventing static electricity
1.5.1
Grounding to prevent damage by 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.
1.5.2
About the earth processing for the destruction prevention by static electricity
Static electricity in the work area can destroy the optical pickup (laser diode) in devices such as DVD 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.
1.5.3
Handling the optical pickup
(1) In order to maintain quality during transport and before installation, both sides of the laser diode on the replacement optical pick-
up are shorted. After replacement, return the shorted parts to their original condition. (Refer to the text.)
(2) 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.
1.5.4
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) Remove solder of the short lands on the flexible wire after replacing the optical pickup. For specific details, refer to the replace-
ment 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 wire 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.
1.5.5
Attention when traverse unit is decomposed
*Please refer to "Disassembly method" in the text for the DVD pickup.
· Apply solder to the short circuit points before the flexible wire is disconnected from the connector on the DVD pickup.
(If the flexible wire is disconnected without applying solder, the DVD pickup may be destroyed by static electricity.)
· In the assembly, be sure to remove solder from the short circuit points after connecting the flexible wire.
Conductive material
(conductive sheet) or iron plate
(caption)
Anti-static wrist strap


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(No.MB141)1-5
1.6
Importance administering point on the safety
Caution: For continued protection against risk of
fire, replace only with same type T1.25A/250V for
AFS1, T5A/125V for AFS2, T160mA/250V for AFS3
and T80mA/250V for AFS4. This symbol specifies
type of fast operating fuse.
Precaution: Pour eviter risques de feux, remplacez
le fusible de surete de AFS1 comme le meme type
que T1.25A/250V, et T5A/125V pour AFS2, et
T160mA/250V pour AFS3, et T80mA/250V pour AFS4.
Ce sont des fusibles suretes qui functionnes rapide.
^