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Website http://biz.lgservice.com
SERVICE MANUAL
DVD HOME THEATER SYSTEM
SERVICE MANUAL
MODEL: DH7520T (DH7520T, S72T1-S/W, S72B1-C)
MODEL: DH7520T
(DH7520T, S72T1-S/W, S72B1-C)
CAUTION
BEFORE SERVICING THE UNIT, READ THE "SAFETY PRECAUTIONS"
IN THIS MANUAL.
P/NO : AFN75754112 AUGUST, 2012
CONTENTS
SECTION 1 ........ SUMMARY
SECTION 2 ........ ELECTRICAL
SECTION 3 ........ CABINET & MAIN CHASSIS
SECTION 4 ........ REPLACEMENT PARTS LIST
1-1
SECTION 1
SUMMARY
CONTENTS
SERVICING PRECAUTIONS ............................................................................................................................ 1-3
ESD PRECAUTIONS ......................................................................................................................................... 1-5
SERVICE INFORMATION FOR EEPROM ........................................................................................................ 1-6
HOW TO UPDATE AUDIO MICOM & DVD PROGRAMS ................................................................................ 1-7
1. How to enter into System Information..................................................................................................... 1-7
2. How to update AUDIO MICOM program ................................................................................................ 1-7
3. How to update DVD program .................................................................................................................. 1-7
SPECIFICATIONS ............................................................................................................................................. 1-8
1-2
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.
Storage in conductive bag Drop 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.
NEVER look directly at the laser beam, and don't allow
contact with fingers or other exposed skin.
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 lens.
Pressure
Magnet
Pressure
How to hold the pick-up
Cotton swab
Conductive Sheet
6) Never attempt to disassemble the pick-up.
Spring has 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.
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 or 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 (1 M)
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.
Armband
Resistor
(1 M)
Resistor
Conductive
(1 M)
Sheet
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 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
SERVICE INFORMATION FOR EEPROM
POWER ON
DETECT NEW EEPROM
DVD LOGO Status (NO Disk status) (OPTION EDIT SCREEN)
NAME HEX
Remote control OPT 1 F1
Pause key1472 in order. OPT 2 00
OPT 3 CD
OPT 4 D4
OPT 5 00
OPT 6 09
Press number 0~9, Press character OPT 7 80
A~F (1~6 for a while) OPT 8 40
OPT 9 00
OPT A 00
Use arrow key ( ) to
move to appropriate position and
make changes
Press pause key once
Change will be applied when power
OFFON.
1-6
HOW TO UPDATE AUDIO MICOM & DVD PROGRAMS
1. How to enter into System Information
1) Enter into SETUP menu in NO Disc.
2) Put on cursor [Highlight] 16:9 wide option of TV aspect in SETUP menu.
3) Press follow key in continuous using remote control.
1 -> 3 -> 9 -> 7 -> 1 -> 3 -> 9 -> ENTER
2. How to update AUDIO MICOM program.
[Update using CD]
1) Change the filename to download as " DH7520_(Version).HEX". Only upper cases are permitted.
ex) DH7520 : " DH7520_1010160.HEX"
2) Copy the file to the root folder of a CD and burn it.
3) Insert the CD to the SET, and move to the DVD function.
Then the upgrade process will be started with the upgrade information.
4) If the upgrade process is complete, the set will be rebooted with "Complete" message.
[Update using USB]
1) Change the filename to download as " DH7520_(Version).HEX". Only upper cases are permitted.
ex) DH7520 : " DH7520_1010160.HEX"
2) Copy the file to the root folder of USB storage.
3) After Home-menu is displayed on Screen of SET, Put the USB into the SET.
Then the upgrade process will be started with the upgrade information.
4) If the upgrade process is complete, the set will be rebooted with "Complete" message.
3. How to update DVD program.
[Update using CD]
1) Copy DVD program(ex: LG_DH7520LD1_Version.Rom) to Root folder of CD, and burn it.
ex) P:LG_DH7520LD1_1010160..Rom
2) Insert the CD to the SET, then after a while the CD tray will be opened with upgrade information on
the screen.
3) Remove the CD, and press "PLAY" key in remote controller.
4) Remove and reconnect the power cable when it changes to logo screen from upgrade information.
Then the upgrade process is completed.
[Update using USB]
1) Copy DVD program(ex: LG_DH7520LD1_Version.Rom) to Root folder of the formatted USB and burn it.
ex) P:\LG_DH7520LD1_1010160.Rom
2) After Home-menu is displayed on Screen of SET, Put the USB into the SET.
Then the upgrade process will be started with the upgrade information.
3) Remove the USB, press "PLAY" key of the remote controller.
4) Remove and reconnect the power cable when it changes to logo screen from upgrade information.
Then the upgrade process is completed.
1-7
SPECIFICATIONS