LG LHST-6245-T, LHT-6245, LHT-6245-W, LHT-6245-T Service manual

DVD/CD RECEIVER

SERVICE MANUAL

MODEL:LH-T6245

LH-T6245A
LHS-T6245T, LHS-T6245W

SERVICE MANUAL MODEL: LH-T6245 (LH-T6245A LHS-T6245T, LHS-T6245W)

CD-R/RW

- 1-1 -

[CONTENTS]

❍ SECTION 1.GENERAL

• SERVICING PRECAUTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2

• ESD PRECAUTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4

• SPECIFICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-5

❍ SECTION 2. AUDIO PART

• AUDIO TROUBLESHOOTING GUIDE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1

• BLOCK DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-5

• SCHEMATIC DIAGRAMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-7

• WIRING DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-17

• PRINTED CIRCUIT DIARGAMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-19

❍ SECTION 3.DVD PART TROUBLESHOOTING GUIDE

• ELECTRICAL TROUBLESHOOTING GUIDE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-1

• DVD PART SCHEMATIC DIAGRAMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-7

❍ 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 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 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 -

❏ SPECIFICATIONS

- 1-6 -

- 2-1 -

SECTION 2. AUDIO PART

❏ AUDIO TROUBLESHOOTING GUIDE

1. POWER SUPPLY CIRCUIT

- 2-2 -

2. FRONT CIRCUIT (1/2)

- 2-3 -

3. FRONT CIRCUIT (2/2)

- 2-4 -

MEMO

❏ BLOCK DIAGRAM

2-5 2-6

2-7 2-8

❏ SCHEMATIC DIAGRAMS

• POWER SCHEMATIC DIAGRAM

2-9 2-10

• MICOM SCHEMATIC DIAGRAM

2-11 2-12

• FRONT SCHEMATIC DIAGRAM

2-13 2-14

• DSP& SCHEMATIC DIAGRAM

2-15 2-16

• SMPS-NARROW&WIDE SCHEMATIC DIAGRAM

2-17 2-18

❏ WIRING DIAGRAM

2-19 2-20

❏ PRINTED CIRCUIT BOARD DIAGRAMS

• MAIN/DVD P.C. BOARD DIAGRAM (BOTTOM)

2-21 2-22

• MAIN/DVD P.C. BOARD DIAGRAM (TOP)

2-23 2-24

• FRONT P.C. BOARD (TOP)

2-25 2-26

• FRONT P.C. BOARD (BOTTOM)

2-27 2-28

• SMPS P.C. BOARD

- 3-1 -

SECTION 3. DVD PART

TROUBLESHOOTING GUIDE

1. Test & debug flow

- 3-2 -

- 3-3 -

- 3-4 -

- 3-5 -

- 3-6 -

3-7 3-8

❏ DVD SCHEMATIC DIAGRAMS

• DVD MPEG & DSP SCHEMATIC DIAGRAM

3-9 3-10

• DVD RF SERVO SCHEMATIC DIAGRAM

4-1 4-2

351

305

313

A47

302

303

451

451

A46

451

451

A26

451

A43

281

286

454

280

275

SECTION 4. EXPLODED VIEWS

❏ CABINET AND MAIN FRAME SECTION

4-3 4-4

• DECK MECHANISM EXPLODED VIEW

LOCA. NO. PART NO. DESCRIPTION SPECIFICATION

A26 6721RJ0856E DECK ASSEMBLY,AUDIO DECK/MECHA DP-7T(HZ)-ESS -(M:M
A01 4861R-0016D CLAMP ASSEMBLY DECK/MECHA DISC DP-7C(7A) -HZ
A02 3041R-M040A BASE ASSEMBLY MAIN DP-7T-HZ
A03 3041R-M061D BASE ASSEMBLY SLED DP-7A-HZ ESS (M: MITSUMI
001 3300R-0547A PLATE CLAMP
002 5016H-1016B MAGNET CLAMP(LDM-R608,10*5,1*1.5T)
003 4860R-0021A CLAMP UPPER DP7
004 4930R-0402A HOLDER CLAMP DP-7A
010 6850R-GK22Z CABLE,FLAT P=1.0 FFC UL2896(0.05X0.65) 11
011 3210R-M002A FRAME UP/DOWN MOLD DP7C
011A 6850R-JW16B CABLE,FLAT P=1.0 FFC UL2896(0.035X0.7) 23
012 5040R-0075D RUBBER DAMPER DP7 (YAMAUCHI 30)
013 4400R-0006B BELT DECK/MECHA DP2-5, DP7C,DP7A OT
014 4470R-0055A GEAR PULLEY
015 6871RJ4415A PWB(PCB) ASSEMBLY,JACK PWB(PCB) TOTAL LOADING-HZ
015A 4681R-1023G MOTOR ASSEMBLY DECK/MECHA LOADING-HZ
015B 4560R-0008A PULLEY MOTOR
015C 4680R-E010A MOTOR(MECH) FEEDING BCZ3B51 SANKYO FOR DP7
017 4470R-0056A GEAR LOADING
018 4974R-0023A GUIDE UP/DOWN
020 3040R-D005A BASE MAIN DP-7T MOLD (SLIM)
021 4680R-C011A MOTOR(MECH) SPINDLE JCL9B68 SANKYO FOR COM
022 4681R-0034D MOTOR ASSEMBLY DECK/MECHA FEEDING DP-7C(7A) ­024 4470R-0131A GEAR PINION DP7C
024A 5006R-0044A CAP SKEW-T DP7C
024B 5006R-0043A CAP SKEW DP7C
025 4470R-0130A GEAR MIDDLE DP7C
026 3390R-0026A TRAY DVD DP-7T MOLD DISC
028 4370R-0082B SHAFT DECK/MECHA PU R DP-7C OTHER
029 4370R-0082A SHAFT PU DP-7C
030 4471R-0013D GEAR ASSEMBLY DECK/MECHA RACK DP-7C(7A) -HZ
031 6716DPH005B PICK UP,DVD PVR-502W R52 0219 MITSUMI PLAY
429 1SZZR-0012A SCREW,DRAWING B-TITE
430 1SZZH-1003A SCREW,DRAWING + D2.0 6MM SWRCH16A/NIY 4.5MM
431 1SZZH-1007B SCREW,DRAWING + D2.0 6MM SWRCH16A/ZNBK 4MM 1
432 1SZZR-0023B SCREW,DRAWING + 1 D1.7 L6.0 SWRCH16A/FZY RAC
433 1SZZR-0050A SCREW,DRAWING + 1 D2.0 L4.5 SWRCH16A/ZNY S-T
435 1SZZR-0011A SCREW,DRAWING MACHINE

- 5-1 -

SECTION 5. SPEAKER SECTION

❏ MODEL : LHS-T6245T

753

755

752

754

751

750

- 5-2 -

❏ MODEL : LHS-T6245W

854

856

855

853

850

852

857

851