LG LH-T6447D User manual

DVD/CD RECEIVER
SERVICE MANUAL
MODEL: LH-T6447D
LHS-T6447C, LHS-T6447W, LHS-T6447T
CD-R/RW
SERVICE MANUAL MODEL: LH-T6447D LHS-T6447C, LHS-T6447W, LHS-T6447T

- 1-1 -
[CONTENTS]
❍SECTION 1.GENERAL
• SERVICING PRECAUTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2
• ESD PRECAUTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4
• SPECIFICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-5
❍SECTION 2. AUDIO PART
• ELECTRICAL TROUBLESHOOTING GUIDE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1
• BLOCK DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-5
• SCHEMATIC DIAGRAMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-7
• WIRNG DIAGRAMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-21
• PRINTED CIRCUIT DIARGAMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-23
❍SECTION 3.DVD PART
• DVD PART ELECTRICAL TROUBLESHOOTING GUIDE . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-1
• DETAILS AND WAVEFORMS ON S STEM TEST AND DEBUGGING . . . . . . . . . . . . . . . . .3-8
• BLOCK DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-21
• DVD PART SCHEMATIC DIAGRAMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-25
❍SECTION 4. EXPLODED VIEWS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-1
❍SECTION 5. SPEAKER PART . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-1
❍SECTION 6. REPLACEMENT PARTS LIST . . . . . . . . . . . . . . . . . . . . . . . . . . .6-1

- 1-2 -
SECTION 1. GENERAL
❏SERVICING PRECAUTIONS
NOTES REGARDING HANDLING O THE PICK-UP
1. Notes for transport and storage
1) The pick-up should always be left in its conductive bag until immediately prior to use.
2) The pick-up should never be subjected to external pressure or impact.
2. Repair notes
1) The pick-up incorporates a strong magnet, and so should never be brought close to magnetic materials.
2) The pick-up should always be handled correctly and carefully, taking care to avoid external pressure and
impact. If it is subjected to strong pressure or impact, the result may be an operational malfunction and/or
damage to the printed-circuit board.
3) Each and every pick-up is already individually adjusted to a high degree of precision, and for that reason
the adjustment point and installation screws should absolutely never be touched.
4) Laser beams may damage the eyes!
Absolutely never permit laser beams to enter the eyes!
Also NEVER switch ON the power to the laser output part (lens, etc.) of the pick-up if it is damaged.
5) Cleaning the lens surface
If there is dust on the lens surface, the dust should be cleaned away by using an air bush (such as used
for camera lens). The lens is held by a delicate spring. When cleaning the lens surface, therefore, a cot-
ton swab should be used, taking care not to distort this.
6) Never attempt to disassemble the pick-up.
Spring by excess pressure. If the lens is extremely dirty, apply isopropyl alcohol to the cotton swab.
(Do not use any other liquid cleaners, because they will damage the lens.) Take care not to use too much
of this alcohol on the swab, and do not allow the alcohol to get inside the pick-up.
Storage in conductive bag Drop impact
NEVER look directly at the laser beam, and don’t let
contact fingers or other exposed skin.
Magnet
How to hold the pick-up
Conductive Sheet
Cotton swab
Pressure
Pressure

- 1-3 -
NOTES REGARDING COMPACT DISC PLAYER REPAIRS
1. Preparations
1) Compact disc players incorporate a great many ICs as well as the pick-up (laser diode). These components
are sensitive to, and easily affected by, static electricity. If such static electricity is high voltage, components
can be damaged, and for that reason components should be handled with care.
2) The pick-up is composed of many optical components and other high-precision components. Care must be
taken, therefore, to avoid repair or storage where the temperature of humidity is high, where strong magnet-
ism is present, or where there is excessive dust.
2. Notes for repair
1) Before replacing a component part, first disconnect the power supply lead wire from the unit
2) All equipment, measuring instruments and tools must be grounded.
3) The workbench should be covered with a conductive sheet and grounded.
When removing the laser pick-up from its conductive bag, do not place the pick-up on the bag. (This is
because there is the possibility of damage by static electricity.)
4) To prevent AC leakage, the metal part of the soldering iron should be grounded.
5) Workers should be grounded by an armband (1M Ω)
6) Care should be taken not to permit the laser pick-up to come in contact with clothing, in order to prevent
static electricity changes in the clothing to escape from the armband.
7) The laser beam from the pick-up should NEVER be directly facing the eyes or bare skin.
Resistor
(1 Mohm) Conductive
Sheet
Resistor
(1 Mohm)
Armband

- 1-4 -
❏ESD PRECAUTIONS
Electrostatically Sensitive Devices (ESD)
Some semiconductor (solid state) devices can be damaged easily by static electricity. Such components
commonly are called Electrostatically Sensitive Devices (ESD). Examples of typical ESD devices are integrated
circuits and some field-effect transistors and semiconductor chip components. The following techniques should
be used to help reduce the incidence of component damage caused by static electricity.
1. Immediately before handling any semiconductor component or semiconductor-equipped assembly, drain off
any electrostatic charge on your body by touching a known earth ground. Alternatively, obtain and wear a
commercially available discharging wrist strap device, which should be removed for potential shock reasons
prior to applying power to the unit under test.
2. After removing an electrical assembly equipped with ESD devices, place the assembly on a conductive sur-
face such as aluminum foil, to prevent electrostatic charge buildup or exposure of the assembly.
3. Use only a grounded-tip soldering iron to solder or unsolder ESD devices.
4. Use only an anti-static solder removal device. Some solder removal devices not classified as "anti-static" can
generate electrical charges sufficient to damage ESD devices.
5. Do not use freon-propelled chemicals. These can generate electrical charges sufficient to damage ESD
devices.
6. Do not remove a replacement ESD device from its protective package until immediately before you are
ready to install it. (Most replacement ESD devices are packaged with leads electrically shorted together by
conductive foam, aluminum foil or comparable conductive materials).
7. Immediately before removing the protective material from the leads of a replacement ESD device, touch the
protective material to the chassis or circuit assembly into which the device will by installed.
CAUTION : BE SURE NO POWER IS APPLIED TO THE CHASSIS OR CIRCUIT, AND OBSERVE ALL
OTHER SA ETY PRECAUTIONS.
8. Minimize bodily motions when handing unpackaged replacement ESD devices. (Otherwise harmless motion
such as the brushing together of your clothes fabric or the lifting of your foot from a carpeted floor can gener-
ate static electricity sufficient to damage an ESD device).
CAUTION. GRAPHIC SYMBOLS
THE LIGHTNING FLASH WITH APROWHEAD S MBOL. WITHIN AN EQUILATERAL TRIANGLE, IS
INTENDED TO ALERT THE SERVICE PERSONNEL TO THE PRESENCE OF UNINSULATED “DAN-
GEROUS VOLTAGE” THAT MA BE OF SUFFICIENT MAGNITUDE TO CONSTITUTE A RISK OF
ELECTRIC SHOCK.
THE EXCLAMATION POINT WITHIN AN EQUILATERAL TRIANGLE IS INTENDED TO ALERT THE
SERVICE PERSONNEL TO THE PRESENCE OF IMPORTANT SAFET INFORMATION IN SERVICE
LITERATURE.

- 1-5 -
GeneralCD/DVDVideo
Amplifier
Speakers
Supplied
Accessories
Tuner
M
AM
[MW]
(* Depending on the sound mode
settings and the source, there may
be no sound output.)
Power supply Refer to main label
Power consumption Ref
4.4kg
er to main label
Mass
External dimensions (W x H x D) 430 x 60 x 350 mm
Operating conditions Temperature: 5°C to 35°C, Operation status: Horizontal
Operating humidity 5% to 85%
Laser Semiconductor laser, wavelength 650 nm
Signal system PAL 625/50, NTSC 525/60
Frequency response (audio) 150 Hz to 18 kHz
Signal-to-noise ratio (audio) More than 70 dB (1 kHz, NOP, 20 kHz LPF/A-Filter)
Dynamic range (audio) More than 70 dB
Harmonic distortion (audio) 0.5 % (1 kHz, at 12W position) (20 kHz LPF/A-Filter)
Video input 1.0 V (p-p), 75Ω , negative sync., RCA jack x 2/ SCART (TO TV)
Video output 1.0 V (p-p), 75Ω , negative sync., RCA jack x 1/ SCART (TO TV)
S-video output ( ) 1.0 V (p-p), 75Ω , negative sync., Mini DIN 4-pin x 1
(C) 0.3 V (p-p), 75Ω
COMPONENT VIDEO OUT ( ) 1.0 V (p-p), 75 ohms, negative sync, RCA jack x 1
(Pb)/(Pr) 0.7 V (p-p), 75 ohms, RCA jack x 2
Tuning Range 87.5 - 108.0 MHz or 65.0 - 74.0 MHz, 87.5 - 108.0 MHz
Intermediate Frequency 10.7 MHz
Signal-to Noise Ratio 60 dB (Mono)
Frequency Response 150 - 8,000 Hz
Tuning Range 522 - 1,611 kHz or 530 - 1,610 kHz
Intermediate Frequency 450 kHz
Stereo mode 45W + 45W (8Ω at 1 kHz, THD 10 %)
Surround mode Front: 45W + 45W (THD 10 %)
Centre*: 45W
Surround*: 45W + 45W (8Ω at 1 kHz, THD 10 %)
Subwoofer*: 60W (6Ω at 30 Hz, THD 10 %)
Inputs VIDEO 1, VIDEO 2, COAXIAL AUDIO, OPTICAL AUDIO
Outputs PHONES: (32Ω , 1.0 V)
Satellite Speaker Centre speaker Passive Subwoofer
(LHS-T6447T) (LHS-T6447C) (LHS-T6447W)
Type 1 Way 1 Speaker 1 Way 1 Speaker 1 Way 1 Speaker
Impedance 8Ω 8Ω 6Ω
Frequency Response 150 - 20,000 Hz 160 - 20,000 Hz 40 - 1,500 Hz
Sound Pressure Level 84 dB/W (1m) 83 dB/W (1m) 70 dB/W (1m)
Rated Input Power 45 W 45 W 60 W
Max. Input Power 90 W 90 W 120 W
Net Dimensions (W x H x D) 93 x 132.5 x 113 mm 210 x 132.5 x 113 mm 160 x 350 x 330 mm
Net Weight 0.6kg 0.65kg 4.5kg
• Speakers . . . . . . . . . . . . . . . . . . . . . . . . . . .6 • Speaker cables . . . . . . . . . . . . . . . . . . .6
• AM loop antenna . . . . . . . . . . . . . . . . . . . . .1 • FM antenna . . . . . . . . . . . . . . . . . . . . . 1
• Remote control . . . . . . . . . . . . . . . . . . . . . .1 • Batteries (AAA) . . . . . . . . . . . . . . . . . . . 2
❏SPECI ICATIONS

- 1-6 -
MEMO

- 2-1 -
❏ ELECTRICAL TROUBLESHOOTING GUIDE
INSERT
POWER CORD.
TURN ON
THE RED LED?
IS POWER ON?
CHECK POWER PLUG
AND POWER SUPPL CIRCUIT.
DOES INITIAL
READ WORK?
DOES IT PLA ?
ES
NO
ES
ES
OK
NO
ES
NO
NO
CHECK POWER SUPPL CIRCUIT.
CHECK LASER CIRCUIT.
CHECK TRACKING SERVO CIRCUIT.
TURN POWER ON.
CHECK FOCUS CIRCUIT.
CHECK DISC.
DOES IT OUTPUT
AUDIO?
ES
NO CHECK AUDIO CIRCUIT.
1. Power check flow
SECTION 2. AUDIO PART

- 2-2 -
2.AUDIO µ.COM CIRCUIT
POWER ON
Does it appear
DVD Error at
FLD?
Does AV 1/2, TV, AUDIO, 
OPTICAL IN, COAXIAL IN, FM87.5 
appear at FLD?
Check
Connector(PN902)if
is normally.
Check power part
of Main B/D.
Check oscillator
of x101.
Check if IC101
PIN1 is High.
Check if IC101
PIN11 is High.
Check if IC101 PIN
17, 46, 72, 90 is high
(5V).
Check if IC101
PIN26 is High.
Replace IC101.
Does CD/DVD
appear at FLD?
Reconnet it.
Refer to SMPS
OK.
Refer to oscillator
Circuit.
Check DVD Reset Waveform.
Check IC101 Reset Wavefrom.
Check 5V line.
Check Power dection Circuit.
Does LOADING
appear at FLD?
Does no Disc or
Time appear at FLD?
Check if DVD an Audio 
Micom Interface is OK.
Check power.
Check DVD Module.
Check SMPS.

- 2-3 -
3. RONT CIRCUIT (1/2)