LG LHS-75SGS, LHS-75SGC, LHS-75SGW Service Manual

- 1-1 -
[CONTENTS]
SECTION 1.GENERAL
• SERVICING PRECAUTIONS ................................................................................................ 1-2
• ESD PRECAUTIONS............................................................................................................. 1-4
• SPECIFICATIONS...................................................................................................................1-5
SECTION 2. ELECTRICAL
• DVD TROUBLESHOOTING GUIDE ...................................................................................... 2-5
• DVD DETAILS AND WAVEFORMS ON SYSTEM TESTAND DEBUGGING..................... 2-13
• WIRING DIAGRAM.............................................................................................................. 2-25
• BLOCK DIAGRAMS............................................................................................................. 2-26
• AUDIO PART SCHEMATIC DIAGRAMS ............................................................................. 2-31
• DVD PART SCHEMATIC DIAGRAMS................................................................................. 2-47
• PRINTED CIRCUIT DIAGRAMS ......................................................................................... 2-53
SECTION 3. EXPLODED VIEWS
• CABINET AND MAIN FRAME SECTION .............................................................................. 3-1
• DECK MECHANISM EXPLODED VIEW .............................................................................. 3-3
• PACKING ACCESSOR Y SECTION ...................................................................................... 3-5
SECTION 4. SPEAKER PART .................................................................................. 4-1
SECTION 5. REPLACEMENT PARTS LIST ............................................................. 5-1
- 1-2 -
SECTION 1. GENERAL
SERVICING PRECAUTIONS
NOTES REGARDING HANDLING OF 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 cot­ton 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 magnet­ism 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 SAFETY 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 gener­ate static electricity sufficient to damage an ESD device).
CAUTION. GRAPHIC SYMBOLS
THE LIGHTNING FLASH WITH APROWHEAD SYMBOL. WITHIN AN EQUILATERAL TRIANGLE, IS INTENDED TO ALERT THE SERVICE PERSONNELTO THE PRESENCE OF UNINSULATED “DAN­GEROUS VOLTAGE” THAT MAY BE OF SUFFICIENT MAGNITUDE TO CONSTITUTE ARISK OF ELECTRIC SHOCK.
THE EXCLAMATION POINTWITHIN AN EQUILATERAL TRIANGLE IS INTENDED TO ALERT THE SERVICE PERSONNEL TO THE PRESENCE OF IMPORTANTSAFETY INFORMATION IN SERVICE LITERATURE.
- 1-5 -
SPECIFICATIONS
GENERAL
Power supply Refer to main label Power consumption Refer to main label Mass 5.5 kg External dimensions (W x H x D) 435 x 54 x 350 mm Operating conditions Temperature: 5°C to 35°C, Operation status: Horizontal Operating humidity 5% to 85%
CD/DVD
Laser Semiconductor laser, wavelength 650 nm Signal system NTSC 525/60 Frequency response (audio) 150 Hz to 18 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 , negative sync., RCA jack x 2 Video output 1.0 V (p-p), 75 , negative sync., RCA jack x 1 S-video output (Y) 1.0 V (p-p), 75 , negative sync., Mini DIN 4-pin x 1
(C) 0.3 V (p-p), 75
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 2
TUNER
FM
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
AM[MW]
Tuning Range 520 - 1,720 kHz Intermediate Frequency 450 kHz
AMPLIFIER
Stereo mode 150W + 150W (6at 1 kHz, THD 10 %) Surround mode Front: 150W + 150W (THD 10 %)
Center*: 150W Surround*: 150W + 150W (6at 1 kHz, THD 10 %) Subwoofer*: 250W (4at 30 Hz, THD 10 %)
SPEAKERS
Front/Rear Speaker Center speaker Passive Subwoofer
(LHS-75SGS) (LHS-75SGC) (LHS-75SGW) Type 2 Way 2 Speaker 2 Way 2 Speaker 1 Way 1 Speaker Impedance 6 6 Ω 4 Ω Frequency Response 145 - 20,000 Hz 120 - 20,000 Hz 50 - 1,500 Hz Sound Pressure Level 85 dB/W (1m) 85 dB/W (1m) 83 dB/W (1m) Rated Input Power 150 W 150 W 250 W Max. Input Power 300 W 300 W 500 W Net Dimensions (W x H x D) 104 x 235 x 120 mm 220 x 115 x 120 mm 195 x 398 x 419 mm Net Weight 1.0kg 1.0kg 6.6kg
(* Depending on the sound mode
settings and the source, there may be no sound output.)
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AUDIO TROUBLESHOOTING GUIDE
1. POWER CHECK FLOW
SECTION 2. ELECTRICAL
INSERT
WER CORD.
PO
TURN ON
THE RED LED?
YES
TURN PO
IS PO
WER ON.
WER ON?
YES
DOES INITIAL
WORK?
READ
YES
NO
NO
NO
CHECK POWER PLUG
AND POWER SUPPLY CIRCUIT
CHECK POWER SUPPLY CIRCUIT.
CHECK LASER CIRCUIT
CHECK FOCUS CIRCUIT
.
.
.
PLAY?
DOES IT
YES
DOES IT OUTPUT
AUDIO?
YES
OK
NO
NO
CHECK DISC.
CHECK TRACKING SERV
CHECK AUDIO CIRCUIT.
O CIRCUIT.
- 2-2 -
2. AUDIO µ-COM CIRCUIT
POWER ON
Does CD/DVD appear at FLD?
Does AV 1/2 FM87.5 appear at FLD?
OK.
Does READING 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.
Does it appear
DVD Error at
FLD?
Check
Connector(PN902)if
is normally.
Check power part
of Main B/D.
Check oscillator
of x101.
Check if IC101 PIN80 is High.
Reconnect it.
Refer to SMPS
Refer to oscillator
Circuit.
Check DVD Reset Waveform.
Check if IC101 PIN92 is High.
Check if IC101 PIN
31, 32, 51, 88 are high
(5V).
Check if IC101 PIN96 is High.
Replace IC101.
Check IC101 Reset Wavefrom.
Check 5V line.
Check Power section Circuit.
- 2-3 -
3. FRONT CIRCUIT (1/2)
PIN104 Pins PIN : -27V PIN 6 : -18V PIN7 : -22V PIN : 5V
- 2-4 -
4. FRONT CIRCUIT (2/2)
CHECK
IF R029, R036~R040,
R046~R051
OK.
REPLACE R029, R036~R040, R046~R051
Check
if PN104 pins10, 11
Waveform OK.
Check
if the Remocon
Waveform of the
PN104 pin16
- 2-5 -
1. POWER CHECK FLOW
DVD TROUBLESHOOTING GUIDE
READING appear at FLD?
Does
Check DVD SECTION
Check
Connector(CN201)
if is normally.
Check
Connector CN202
Check
Connector CN203
Check
voltage each pin for PN902
Check SMPS board regulator
Check Connector PN902
- 2-6 -
2. SYSTEM OPERATION FLOW
Power On
1. 8032 initializes SERVO, DSP & RISC registers
2. Write RISC code to SDRAM
3. Reset RISC
Show LOGO
YES
Tray Closed?
NO
Tray Close to Closed position
SLED at Inner
Side ?
NO
SLED Moves to Inner Positi on
1. Judge whether have disc and disc type
2. Jump to related disc reading procedure
Reci eve
OPEN/CLOSE
Key?
YES
YES
NO
1. Execute Pressed Key & IR Key
2. System operation Routine Loop
1. Stop Playback & Open Tray
2. Display tray open message & LOGO
NO
Receive
CLOSE Key?
YES
- 2-7 -
3. TEST & DEBUG FLOW
TEST
Check the AC Voltage
Power PCBA(120V)
YES
Switch on the Power PCBA
Is the DC Voltage
outputs OK?
(5V,3.3V, 8V, 12V, -12V, 11.5V)
YES
Make sure the main PCBA don't
short on VCCs and switch it on.
NO
NO
Replace power PCBA or
AC transformer.
Repair or Replace P ower PCBA
Is 3.3V and 1.8V DC
outputs normal on main
PCBA?
YES
Connect to PC RS232 Cable and update the FLASH memory code.
Update FLASH
successfully?
YES
A
NO
Check the regulators or related diodes.
1. Check 27MHz system clock.
NO
2. Check system reset circuit.
3. Check FLASH R/W enable signal PRD,RWR.
4. Check RS232 SIGNALS.
5. Check FLASH Memory related circuit.
- 2-8 -
A
RESET or Power On.
Show LOGO?
NO
Flash Memory operates
properly?
YESYES
SDRAM works properly?
YES
MT1389 VIDEO outputs
properly?
YES
Have TV signal output?
YES
Check AV cable connection to TV set.
NO
NO
NO
NO
Check connection lines between FLASH & MT1389 and the FLASH access time whether is suitable or not.
Check connection lines between SDRAM & MT1389 and the SDRAM is damaged.
Check the related circuit of MT1389.
Check the filtering and amp circuit of TV signal.
Does Tray move
inside when it is not
at closed position?
YES
B
NO NO
Normal TROUT &
TRIN signals?
YES
Normal TRCLOSE & TROPEN signal?
YES
Normal LOAD+ &
LOADsignal?
YES
Check the cable connection between main PCBA and loader.
NO
NO
Check the load OPEN & CLOSE switch
Check the Tray control IO pins on MT1389 & IP4504.
Check the Tray control amplifying circuit on Motor driver.
- 2-9 -
B
Does
the SLED move
to inner side when it is at
outter position?
YES YES
NO NO
Motor Driver STBY
Pin is High?
Check the connection line of
STBY signal.
Do not put in disc and tray
close.
Optical Lens has
movements for searching
Focus?
Is FMSO DC Level higher
than 1.4V?
YES
SL+ and SL- output
properly?
YES
Check the cable connection with
NO NO
MECHA.
Proper FOSO outputs
to motor driver?
NO
NO
Check the related circuit of FMSO.
Check the amp circuit on motor driver.
Check FOSO connection on MT1389 and motor dirver.
YESYES
Proper F+ & F- outputs?
YES
C
Check cable connect on with
pick-up head.
NO
Check the amp circuit on motor
dirver.
- 2-10 -
C
Laser turns on when reading disc?
YES
Put disc in? Laser off
YES
Disc ID is correct?
NO
NO
NO
LD01 or LD02 output properly?
Collector voltage of power transistor is OK?
Check cable connection between transistor ouput and pick-up head.
Proper RFL signal on MT1389?
YES
YES
YES
NO
NO
NO
Check the laser power circuit on MT1336 and connecting to power transistor.
Check the related circuit on laser power transistor
Check the related circuit on MT1389 RFL signal.
YES
Does spindle rotate?
YES
D
NO
Check LDO1 & LDO2 signal
Proper DMSO signal on MT1389
YES
SP+ & SP- output properly?
YES
Check the cable connection between spindle and main PCBA.
NO
NO
Check DMSO related circuit on MT1389.
Check the spindle control amp circuit of motor driver.
- 2-11 -
D
YES
Focus ON OK?
YES
Track On OK?
YES
NO NO
NO
Proper signals on
A,B,C,D of MT1389
YES
Check FEO signal
on MT1389
YES
Check FOSO signal on MT1389
Normal TEO Signal on
MT1389?
YES
Properly TRSO signal
on MT1389?
YES
NO
NO
NO
Check connections between
MT1389 and pick-up head.
Check the FOSO connection on
MT1389 and motor driver.
Check the related circuit on MT1389
Check the TRSO
connection on MT1389
and motor dirver.
Disc is play ?
YES
E
NO
T+ & T- output
properly?
YES
Check cable connection on
pick-up head.
Check RFO & RFLVL signal waveform.
NO
Check the tracking control
amp circuit on motor
driver.
- 2-12 -
E
Normal Audio output when disc playback?
YES
Normal IR.VFD & Front pannel key functions?
YES
TEST END
NO NO
NO
Audio PWM IC received
correct data stream?
YES
Normal Audio PWM IC
out?
YES
Check Audio filter,amplify,mute
IR.VFD Front pannelkey & MT1389
Check the cable connection on
circuit.
Communications between
is normally?
YES
Front pannel.
NO
NO
Check connection between MT1379
& Audio PWM IC.
Check the related
circuit of Audio PWM IC.
Check communication lines on
MT1389.
- 2-13 -
DVD DETAILS AND WAVEFORMS ON SYSTEM TEST AND DEBUGGING
1. SYSTEM 27MHz CLOCK,RESET,FLASH R/W SIGNAL
1) MT1389 main clock is at 27MHz(X601)
2) MT1389 reset is high active
FIG 1-1
FIG 1-2
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3) RS232 waveform during procedure(Downloading)
4) Flash R/W enable signal during download(Downloading)
FIG 1-3
FIG 1-4
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