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LCD TV
SERVICE MANUAL
CHASSIS : ML-024D
MODEL : RZ-20LA70
CAUTION
BEFORE SERVICING THE CHASSIS,
READ THE SAFETY PRECAUTIONS IN THIS MANUAL.
Oct.,2003
P/NO : 3828VD0168C Printed in Korea
CONTENTS
CONTENTS .............................................................................................. 2
PRODUCT SAFETY ..................................................................................3
DESCRIPTION OF CONTROLS .............................................................. 4
ADJUSTMENT INSTRUCTION .................................................................7
TROUBLE SHOOTING ............................................................................13
PRINTED CIRCUIT BOARD ....................................................................14
BLOCK DIAGRAM...................................................................................17
EXPLODED VIEW .................................................................................. 18
EXPLODED VIEW PARTS LIST ..............................................................19
REPLACEMENT PARTS LIST ............................................................... 20
SVC. Sheet .................................................................................................
- 2 -
PRODUCT SAFETY
IMPORTANT SAFETY NOTICE 1. Immediately before handling any semiconductor component or
This manual was prepared for use only by properly trained audiovisual service semiconductor-equipped assembly, drain off any electrostatic charge on the
technicians. When servicing this product, under no circumstances should the body by touching a known earth ground. Alternatively, obtain and wear a
original design be modified or altered without permission from LG Electronics commercially available discharging wrist strap device, which should be
Inc. All components should be replaced only with types identical to those in the removed for potential shock reasons prior to applying power to the unit under
original circuit and their physical location, wiring, and lead dress must conform test.
to original layout upon completion of repairs. If any fuse (or Fusible Resistor) in 2. After removing an electrical assembly equipped with ES devices, place the
this TV receiver is blown, replace it only with the factory specified fuse type and assembly on a conductive surface such as an ESD mat, to prevent
rating. When replacing a high wattage resistor (Oxide Metal Film Resistor, over electrostatic charge buildup or exposure of the assembly.
1W), keep the resistor 10mm away from PCB. Always keep wires away from 3. Use only a grounded-tip soldering iron to solder or unsolder ES devices.
high voltage or high temperature parts. 4. Use only an anti-static solder removal device. Some solder removal devices
not classified as "anti-static" can generate electrical charges sufficient to
Special components are also used to prevent shock and fire hazard. damage ES devices.
These components are indicated by the letter "x" included in their component 5. Do not use freon-propelled chemicals. These can generate electrical charge
designators and are required to maintain safe performance. No deviations are sufficient to damage ES devices.
allowed without prior approval by LG Electronics Inc. Service work should be 6. Do not remove a replacement ES device from its protective package until
performed only after you are thoroughly familiar with these safety checks and immediately before you are ready to install it. (Most replacement ES devices
servicing guidelines. are packaged with leads electrically shorted together by conductive foam,
aluminum foil, or comparable conductive material.)
Circuit diagrams may occasionally differ from the actual circuit used. 7. Immediately before removing the protective material from the leads of a
This way, implementation of the latest safety and performance improvement replacement ES device, touch the protective material to the chassis or circuit
changes into the set is not delayed until the new service literature is printed. assembly into which the device will be installed.
CAUTION: Do not attempt to modify this product in any way. Caution: Be sure no power is applied to the chassis or circuit, and observe
Never perform customized installations without manufacturer's all other safety precautions.
approval.
Unauthorized modifications will not only void the warranty, but may 8. Minimize bodily motions when handling unpackaged replacement ES
lead to property damage or user injury. devices. (Otherwise, seemingly harmless motion, such as the brushing
together of your clothing or the lifting of your foot from a carpeted floor, can
generate static electricity sufficient to damage an ES device.)
GENERAL GUIDANCE
An isolation Transformer should always be used during the servicing
of a receiver whose chassis is not isolated from the AC power line. Use a
transformer of adequate power rating to protect against personal injury from
electrical shocks. It will also protect the receiver and its components from being
damaged by accidental shorts of the circuitry that may be inadvertently
introduced during the service operation.
Before returning the receiver to the customer, always perform an AC leakage
current check on the exposed metallic parts of the cabinet, such as antennas,
terminals, etc., to be sure the set is safe to operate
without damage of electrical shock.
LEAKAGE CURRENT COLD CHECK
(ANTENNA COLD CHECK)
With the instrument's AC plug removed from AC source, connect an electrical
jumper across the two AC plug prongs. Place the AC switch in the on position,
connect one lead of ohm-meter to the AC plug prongs tied together, and touch
other ohm-meter lead in turn to each exposed metallic parts such as antenna
terminals, phone jacks, etc. If the exposed metallic part has a return path to the
chassis, the measured resistance should be between 1M and 5.2M. When
the exposed metal has no return path to the chassis the reading must be
infinite. Any other abnormality that exists must be corrected before
the receiver is returned to the customer.
ELECTROSTATICALLY SENSITIVE DEVICES
Some semiconductor (solid-state) devices can be damaged easily by static
electricity. Such components commonly are called Electrostatically Sensitive
(ES) Devices. Examples of typical ES 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.
- 3 -
DESCRIPTION OF CONTROLS
All the functions can be controlled with the remote control handset.
Some functions can also be adjusted with the buttons on the side
panel of the set.
Remote control handset
MUTE POWER
Before you use the remote control handset, please install the bat-
1 9
teries. See the next page.
TV/AV I/II
2 10
LIST Q.VIEW MENU 1. MUTE
3 11 switches the sound on or off.
4
2. TV/AV
PR
selects TV or AV monitor mode.
5 OK clears the menu from the screen.
VOL VOL
PR
switches the set on from standby.
3. LIST
1 2 3 displays the programme table.
6 4 5 6
4. Q.VIEW
returns to the previously viewed programme.
7 8 9
selects a favourite programme.
7 SSM 0 PSM 12
5. D / E (Programme Up/Down)
SLEEP TEXT
selects a programme or a menu item.
8
UPDATE TIME switches the set on from standby.
F / G (Volume Up/Down)
SIZE MIX 13
adjusts the volume.
HOLD REVEAL adjusts menu settings.
? OK
INDEX MODE
i M
accepts your selection or displays the current mode.
6. NUMBER BUTTONS
switches the set on from standby or directly select a number.
7. SSM (Sound Status Memory)
recalls your preferred sound setting.
8. SLEEP
sets the sleep timer.
- 4 -
9. POWER
switches the set on from standby or off to standby.
10. I/II
selects the language during dual language broadcast.
selects the sound output (option).
11. MENU
MUTE POWER
selects a me
1 9
TV/AV I/II
12. PSM (Picture Status Memory)
2 10
recalls your preferred picture setting.
LIST Q.VIEW MENU
3 11
13. TELETEXT BUTTONS (option) 4
These buttons are used for teletext.
For further details, see the `Teletext' section. PR
5 OK
* : No function VOL
PR
VOL
COLOURED BUTTONS : These buttons are used for teletext (only
TELETEXT models) or programme edit.
1 2 3
6 4 5 6
7 8 9
7 SSM 0 PSM 12
SLEEP TEXT
8
UPDATE TIME
SIZE MIX 13
HOLD REVEAL
?
INDEX MODE
i M
- 5 -
Side panel