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Service Manual
TFT LCD MONITOR

Model : L500B

DAEWOO ELECTRONICS CO., LTD
OVERSEAS SERVICE DEPT.
TABLE OF CONTENTS
SAFETY PRECAUTIONS ................................................................................................. 2
GENERAL SAFETY INFORMATION.................................................................................. 3
SERVICING PRECAUTIONS ........................................................................................... 4
GENERAL INFORMATION ............................................................................................. 8
PIN CONNECTOR ....................................................................................................... 9
OPERATION & ADJUSTMENT ........................................................................................ 10
ALIGNMENT PROCEDURE ............................................................................................ 14
TROUBLE SHOOTING HINTS .......................................................................................... 15
BLOCK DIAGRAM ....................................................................................................... 22
PCB LAYOUT ............................................................................................................... 23
SCHEMATIC DIAGRAM ................................................................................................ 25
EXPLODED VIEW & MECHANICAL PARTS LIST ................................................................ 33
INFORMATION OF PART DESCRIPTION ......................................................................... 34
ELECTRICAL PARTS LIST ................................................................................................ 35

1
SAFETY PRECAUTIONS
CAUTION
No modifications of any circuit should be attempted. Service work should only be performed after you
are thoroughly familiar with all of the following safety check and servicing guidelines.

u Fire & Shock Hazard
w In servicing, pay attention to original lead dress especially in the high voltage circuit. if a short circuit
is found, replace all parts which have been overheated as a result of the short circuit.
w All the protective devices must be reinstalled per original design.
w Soldering must be inspected for possible cold solder points, frayed leads, damaged insulation, solder
splashes or sharp solder points. Be certain to remove all foreign materials.

u Implosion Protection
TFT LCD in this monitor employs integral implosion protection system, but care should be taken to avoid
damage and scratching during installation.
Use only same type replacement TFT panel.

IMPORTANT SAFETY NOTICE
There are special components used in analog TFT LCD color display, which are important for safety.
These parts are shaded on the schematic diagram and on the replacement parts list. It is essential
that these critical parts should be replaced with manufacturer' specified parts to prevent X-radiation,
s
shock, fire or other hazards. Do not modify the original design without getting a written permission
from DAEWOO ELECTRONICS CO. or this will void the original parts and labor warranty.

2
GENERAL SAFETY INFORMATION
u Terms in the manual

CAUTION Statements identify conditions or practices that could result in damage to the equipment or
other property.
WARNING Statements identify conditions or practices that could result in personal injury or loss of life.

u Terms as marked on equipment

CAUTION Statements indicate a personal injury hazard not immediately accessible as one reads the
marking, or a hazard to properly including the equipment itself.
WARNING Statements indicate a personal injury hazard immediately accessible as one reads the marking

u Symbols in the manual
This symbol indicates where applicable cautionary or other information is to be found.

u Symbols as marked on equipment
Protective GROUND terminal

u High Voltage Warning And Critical Component Warning Label
Following warning label is on the backlight outside.

WARNING
This product includes critical mechanical and electrical parts. For continued safety, replace critical
components indicated in the service manual only with exact replacement parts given in the parts list.
Refer to service manual for measurement procedures and proper service adjustments.

3
SERVICING PRECAUTIONS
CAUTION
Before servicing instruments covered by this service manual, its supplements and addendum, read
and follow the SAFETY PRECAUTIONS of this manual.

NOTE
If unforeseen circumstances create conflict between the following servicing precautions and any of
the safety precautions on page 1 of this manual, always follow the safety precautions.
Remember: Safety First.

u General Servicing Precautions
1. Always unplug the AC power cord from the AC power source before:
a. Removing or reinstalling any component, circuit board, module, or any other instrument assembly.
b. Disconnecting or reconnecting any electrical plug or other electrical connection.
c. Connecting a test substitute in parallel with an electrolytic capacitor in the instrument.

CAUTION
A wrong part substitution or incorrect polarity installation of electrolytic capacitors may result in a
explosion hazard.

2. Do not any spray chemicals on or near this instrument or any or its assemblies.
3. Unless specified otherwise in this service manual, clean electrical contacts by applying the following
mixture to the contacts with a pipe cleaner, cotton-tipped stick or comparable nonabrasive applicator:
10% (by volume) Aceton and 90% (by volume) isopropyl alchohol (90%-99% strength).

CAUTION
This is a flammable mixture. Unless specified otherwise in this service manual, lubrication of contacts
is not required.

4. Do not apply AC power to this instrument and/or any of its electrical assemblies unless all solid-state
device heat sinks are correctly installed.
5. Always connect the test instrument ground lead to the appropriate instrument chassis ground before
connecting the test instrument positive lead. Always remove the test instrument ground lead last.
6. Use only the test fixtures specified in this service manual with this instrument.

CAUTION
Do not connect the test fixture ground strap to any heatsink in this instrument.

4
SERVICING PRECAUTIONS

u Electrostatically Sensitive (ES) Devices
Some semiconductor (solid state) devices can be damaged easily by static electricity.
Such components commonly are called Electrostatically Sensitive (ES) Devices.
The examples of typical ES devices are integrated circuits, 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 ES 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 ES devices.
4. Use only an anti-static type solder removal device. Some solder removal devices not classified as
"anti-static" can generate enough electrical charges to damage ES devices.
5. Do not use freon-propelled chemicals. These can generate enough electrical charges to damage ES devices.
6. Do not remove a replacement ES device from its protective package until immediately before you are
ready to install it. (Most replacement ES devices are packaged with leads electrically shorted together
by conductive foam, aluminum foil or comparable conductive material).
7. Immediately before removing the protective material from the leads of a replacement ES device,
touch the protective material to the chassis or circuit assembly into which the device will be installed.

CAUTION
Be sure that no power is applied to the chassis or circuit, and observe all other safety precautions.

8. Minimize bodily motions when handling unpackaged replacement ES devices. (Otherwise harmful
motion such as the brushing together of your clothes fabric or the lifting of your foot from a carpeted
floor can generate enough static electricity to damage an ES devices).

u General Soldering Guidelines
1. Use a grounded-tip, low-wattage soldering iron with appropriate tip size and shape that will maintain
tip temperature within a 550