LG HT552TH User manual

DVD/CD RECEIVER
SERVICE MANUAL
MODEL : HT552TH SH52TH-C, SH52TH-S, SH52TH-W
SERVICE MANUAL
P/NO : AFN31640733 DECEMBER, 2006
MODEL : HT552TH
SH52TH-C, SH52TH-S,
SH52TH-W
http://biz. gservice.com

1-1
[CONTENTS]
SECTION 1. GENERAL
• SERVICING PRECAUTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2
• ESD PRECAUTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4
• SERVICE INFORMATION FOR EEPROM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-5
• SPECIFICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-7
SECTION 2. AUDIO PART
• AUDIO TROUBLESHOOTING GUIDE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1
• WIRING DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-4
• BLOCK DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-6
• CIRCUIT DIAGRAMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-
• PRINTED CIRCUIT DIARGAMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2
SECTION 3. DVD & AMP PART
• ELECTRICAL TROUBLESHOOTING GUIDE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-1
• DVD & AMP CIRCUIT DIAGRAMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-22
• PRINTED CIRCUIT DIARGAMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-2
SECTION 4. EXPLODED VIEWS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-1
SECTION 5. SPEAKER PART . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-1
SECTION 6. REPLACEMENT PARTS LIST . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-1

1-2
SERVICING PRECAUTIONS
NOTES REGARDING ANDLING OF T E 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
SECTION 1. GENERAL

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 surface
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 T E C ASSIS OR CIRCUIT, AND OBSERVE ALL OT ER
SAFETY PRECAUTIONS.
. 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. GRAP IC SYMBOLS
THE LIGHTNING FLASH WITH APROWHEAD SYMBOL. WITHIN AN EQUILATERAL TRIANGLE, IS
INTENDED TO ALERT THE SERVICE PERSONNEL TO THE PRESENCE OF UNINSULATED
“DANGEROUS VOLTAGE” THAT MAY 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 SAFETY INFORMATION IN SERVICE
LITERATURE.

1-5
SERVICE INFORMATION FOR EEPROM(DVD PART)
POWER ON
DVD LOGO Status (NO Disk status)
Remotecontrol
Pause key-->1-->4-->7-->2 in order.
Press number 0~9, Press charater
A~F (1~6 for a while)
Use arrow key ( ) to
move to approprite position and
make changes
Press pause key once
Change will be applied when power
OFF-->ON.
NAME EX
OPT 1 00
OPT 2 00
OPT 3 00
OPT 4 00
OPT 5 00
OPT 6 00
OPT 7 00
OPT 00
OPT 9 00
OPT A 00
OPT B 00
OPT C 00
OPT D 00
OPT E 00
OPT F 00
OPT G 00
DETECT NEW EEPROM
(OPTION EDIT SCREEN)
*Refer to page 6-1.

1-6
SERVICE INFORMATION FOR EEPROM (AMP PART)
POWER ON
FLD no disc status
Remotecontrol ‘2’ + Front ‘STOP’
push same timing during 5s
FLD ‘00….
Use arrow key ( ) move
to appropriate position and make
changes
Press ENTER key once
FLD ‘write ok’ or ‘up ok’
Remotecontrol ‘2’ + Front ‘STOP’
push same timing
FLD display E2P CLR or EP CLR
Auto power off
NAME EX
00 86
01 FA
02 23
03 00
04 00
DETECT NEW EEPROM
(OPTION EDIT SCREEN)

1-7
SPECIFICATIONS
GENERAL
Power supply Refer to main label.
Power consumption Refer to main label.
Net Weight 3.6 kg
External dimensions (W x H x D) 430 x 70 x 311 mm
Operating conditions Temperature: 5°C to 35°C, Operation status: Horizontal
Operating humidity 5% to 5%
Laser Semiconductor laser, wavelength 650 nm
CD/DVD
Signal system PAL 625/50, NTSC 525/60
Frequency response (audio) 200 Hz to 1 kHz
Signal-to-noise ratio (audio) More than 75 dB (1 kHz, NOP -6 dB, 20 kHz LPF/A-Filter)
Dynamic range (audio) More than 70 dB
Harmonic distortion (audio) 0.5 % (1 kHz, at 1W position) (20 kHz LPF)
VIDEO
Video input 1.0 V (p-p), 75 Ω, negative sync., RCA jack x 1
Video output 1.0 V (p-p), 75 Ω, negative sync., RCA jack x 1/ SCART (TO TV)
COMPONENT VIDEO OUT (Y) 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 1
TUNER
FM
Tuning Range 7.5 - 10 .0 MHz or 65.0 - 74.0 MHz, 7.5 - 10 .0 MHz
Intermediate Frequency 10.7 MHz
Signal-to Noise Ratio 60 dB (Mono)
Frequency Response 140 - ,000 Hz
AM [MW]
Tuning Range 522 - 1,620 kHz or 520 - 1,720 kHz
Intermediate Frequency 450 kHz
AMPLIFIER
Stereo mode 70 W + 70 W (4Ω at 1 kHz, THD 10 %)
Surround mode Front: 70 W + 70 W (THD 10 %)
Center*: 70 W
Surround*: 70 W + 70 W (4Ω at 1 kHz, THD 10 %)
Subwoofer*: 150 W (3Ω at 30 Hz, THD 10 %)
Inputs AUDIO IN, OPTICAL IN
Outputs MONITOR OUT, EURO AV (TO TV) OUT
COMPONENT VIDEO OUT
SPEAKERS
Front/Rear Speaker Center speaker Passive Subwoofer
(SH52TH-S) (SH52TH-C) (SH52TH-W)
Type 2 Way 3 Speaker 2 Way 3 Speaker 1 Way 1 Speaker
Impedance 4 Ω 4 Ω 3 Ω
Frequency Response 100 - 20000 Hz 150 - 20000 Hz 40 - 1500 Hz
Sound Pressure Level 2 dB/W (1m) 2 dB/W (1m) 0 dB/W (1m)
Rated Input Power 70 W 70 W 150 W
Max. Input Power 140 W 140 W 300 W
Net Dimensions (W x H x D) 260 x 1100 x 260 mm 330 x 6 x 121 mm 212 x 395 x 341 mm
Net Weight 3.0 kg 1.15 kg 6.0 kg
(* Depending on the sound mode
settings and the source, there may
be no sound output.)

2-1
SECTION 2. AUDIO PART
AUDIO TROUBLES OOTING GUIDE
1. POWER SUPPLY CIRCUIT
Insert power cord
YES
YES
YES
YES
YES
YES
YES
Turn power on.
NO
Check power plug and power supply circuit.
NO
Check power supply circuit.
NO
Check laser circuit.
Check focus circuit.
Check disc.
NO
NO
Check tracking servo circuit.
Check audio circuit.
Does red power led turn on?
Is power on?
Does initial read work?
Does it play?
Does it output audio?
OK

2-2
2. FRONT CIRCUIT (1/2)
YES
YES YES
YES YES
YES
YES
NO NO Reconnect it.
(Refer to notice *1)
Tuner off the red led? Check if the PN301 is ok?
NO NO
NO
Refer to smps part.
Check pattern and
resoldering
Is digitron on normally?
Check if all buttons
are ok?
Check if the front
power is ok?(*2)
Check if the DIS301
is ok?
NO
1
Check if the
remotecontrol is ok?
NO
2
Power on.
Front b/d ok.
*1 : When it is needed to reconnected FFC cable into PN301
Short 1pin of PN103 with 1 pin of CN901 in amp part
*2 : PN603 Pins.
PIN1 : -35 VKK
PIN2 : -30 FL+
PIN3 : -33 FL-
PIN7 : +5V
PIN13 : +5VA

2-3
3. FRONT CIRCUIT (2/2)
YES
YES
YES
NO
Reffer to power(SMPS).
NO
Replack R345 ~ R350, R154.
Check if the power part of the front is ok?
Check if R345~R350, R150 ok?
Refer to micom circuit.
1
YES
YES
YES
NO
Reffer to power(SMPS).
NO
Reffer to micom circuit.
NO
Check rm circuit
Check if the power part of the front is ok?
Check if the remotecontrol waveform of the
PN301 pin11 is ok?
Check if the RC2 voltage is ok(5V)?
YES
Resoldering or replace RC2.
2

2-4 2-5
WIRING DIAGRAM
FAN
VOLUME
DC
ACK
MD
SMPS PCB
FRONT PCB
VFD
AMP PCB
SPEAKER TERMINAL
MAIN PCB
HDMI
JACK SCART JACK AV JACK
COMPONENT S/W OPTICAL IN
HEAT SINK
PN602 PN203
PN601
CN602
PN603
PN202
PN206
PN302
PN202 6630R-FB05K
6630XE00111
PN204
11PIN
MIC1
CN301
EAD35219301
MIC2
USB
STEREO
PN301
PN103
P4401
6630XE00123
23PIN
CN902CN901
P4402
6630XE00109
3PIN
15PIN
9PIN
14PIN
TUNER
KEY PCB
561-711O
6630XE00120 6630XE001206630XE00124
EAD35214501
EAD35219501
561-715N
561-661B
6630XE01224
6630XE00118
561-711C
6630R-FB05R
CABLE3 EAD35201502
CABLE1 EAD35201101
CABLE4 EAD35201302
CABLE2 EAD35632101
EAD35214501
EAD35219501

2-6 2-7
BLOCK DIAGRAM
IC508
PORTA
BLE
IC204
AK5358
ADC
IC203
NJM4580
OPAMP
DVD_DI DVD_CLK DVD_CE DVD_DO
IC501
IP9009A
IC601
TAS5152
TAS5152
TAS5152
TAS5152
FL
FR
WF
C
RL
RR

2-8 2-9
CIRCUIT DIAGRAMS
1. SMPS(POWER) CIRCUIT DIAGRAM
A
1
2
3
4
5
6
7
8
9
10
11
12
B C D E F G H I J K L M N O P Q R ST
NOTES) Symbol denotes AC ground.
NOTES) Symbol denotes DC chassis ground.
NOTE) Warning
NOTE) Parts that are shaded are critical
NOTE) With respect to risk of fire or
NOTE) electricial shock.
IMPORTANT SA ETY NOTICE
WHEN SERVICING THIS CHASSIS, UNDER NO CIR-
CUMSTANCES SHOULD THE ORIGINAL DESIGN BE
MODIFIED OR ALTERED WITHOUT PERMISSION
FROM THE LG CORPORATION. ALL COMPONENTS
SHOULD BE REPLACED ONLY WITH TYPES IDENTI-
CAL TO THOSE IN THE ORIGINAL CIRCUIT. SPECIAL
COMPONENTS ARE SHADED ON THE SCHEMATIC
FOR EASY IDENTIFICATION.
THIS CIRCUIT DIAGRAM MAY OCCASIONALLY DIF-
FER FROM THE ACTUAL CIRCUIT USED. THIS WAY,
IMPLEMENTATION OF THE LATEST SAFETY AND
PERFORMANCE IMPROVEMENT CHANGES INTO
THE SET IS NOT DELAYED UNTIL THE NEW SERVICE
LITERATURE IS PRINTED.
NOTE :
1. Shaded( parts are critical for safety. Replace only
with specified part number.
2. Voltages are DC-measured with a digital voltmeter
during Play mode.

2-10 2-11
2. POWER INTER ACE CIRCUIT DIAGRAM
A
1
2
3
4
5
6
7
8
9
10
11
12
B C D E F G H I J K L M N O P Q R ST

2-12 2-13
3. µ-COM(MAIN) CIRCUIT DIAGRAM
A
1
2
3
4
5
6
7
8
9
10
11
12
B C D E F G H I J K L M N O P Q R ST

2-14 2-15
4. SERVO CIRCUIT DIAGRAM
A
1
2
3
4
5
6
7
8
9
10
11
12
B C D E F G H I J K L M N O P Q R ST

2-16 2-17
5. I/O CIRCUIT DIAGRAM
A
1
2
3
4
5
6
7
8
9
10
11
12
B C D E F G H I J K L M N O P Q R ST

2-18 2-19
6. MIC & USB & PTB CIRCUIT DIAGRAM
A
1
2
3
4
5
6
7
8
9
10
11
12
B C D E F G H I J K L M N O P Q R ST

2-20 2-21
7. POWER KEY CIRCUIT DIAGRAM
A
1
2
3
4
5
6
7
8
9
10
11
12
B C D E F G H I J K L M N O P Q R ST