Daewoo L500B Service Manual

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

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.

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.

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’s specified parts to prevent X-radiation, 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.

GENERAL SAFETY INFORMATION

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.

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

Symbols in the manual

This symbol indicates where applicable cautionary or other information is to be found.

Symbols as marked on equipment

Protective GROUND terminal

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.

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.

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.

SERVICING PRECAUTIONS

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).

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°F-660°F (288°C-316°C) range.

2. Use an appropriate gauge of RMA resin-core solder composed of 60 parts tin/40 parts lead.

3. Keep the soldering iron tip clean.

4. Throughly clean the surface to be soldered. Use a small wire-bristle (0.5 inch or 1.25cm) brush with a metal handle. Do not use freon-propelled spray-on cleaners.

5. Use the following soldering technique: a. Allow the soldering iron tip to reach normal temperature (550°F to 660°F or 288°C to 316°C) b. Hold the soldering iron tip and solder strand against the component lead until the solder melts. c. quickly move the soldering iron tip to the junction of the component lead and the printed circuit foil, and hold it there only until the solder flows onto and around both the component lead and the foil. d. Closely inspect the solder area and remove any excess or splashed solder with a small wire-bristle brush.

CAUTION

Work quickly to avoid overheating the circuit board printed foil.

SERVICING PRECAUTIONS

FIGURE1. USE SOLDERING IRON TO PRY LEADS

IC Removal / Replacement

Some utilized chassis circuit boards have slotted (oblong) holes through which the IC leads are inserted and then bent flat against the circuit foil. When holes are slotted, the following technique should be used to remove and replace the IC. When working with boards using the familiar round hole, use the standard technique as outlined in paragraphs 5 on the page under the title of general soldering guidelines.

Removal

1. Desolder and straighten each IC lead in one operation by gently prying up on the lead with the soldering iron tip as the solder melts.

2. Draw away the melted solder with an anti-static suction-type solder removal device (or with desoldering braid before removing the IC.

Replacement

1. Carefully insert the replacement IC in the circuit board.

2. Carefully bend each IC lead against the circuit foil pad and solder it.

3. Clean the soldered areas with a small wire-bristle brush. (lt is not necessary to reapply acrylic coating to the area).

“Small-Signal” Discrete Transistor Removal/Replacement

1. Remove the defective transistor by clipping its leads as close as possible to the component body.

2. Bend the end of each of three leads remaining on the circuit board into a “U” shape.

3. Bend the replacement transistor leads into a “U” shape.

4. Connect the replacement transistor leads to the corresponding leads extending from the circuit board and crimp the “U” with long nose pliers to insoure metal-to-metal contact, then solder each connection.

SERVICING PRECAUTIONS

Power IC, Transistor or Devices Removal / Replacement

1. Heat and remove all solders from the device leads.

2. Remove the heatsink mounting screw (if applicable).

3. Carefully remove the device from the circuit board.

4. Insert new device in circuit board.

5. Solder each device lead, and clip off excess lead.

6. Replace heatsink.

Diode Removal / Replacement

1. Remove defective diode by clipping its leads as close as possible to diode body.

2. Bend the two remaining leads perpendicularly to the circuit board.

3. Observing diode polarity, wrap each lead out of the new diode around the corresponding lead on the circuit board.

4. Securely crimp each connection and solder it.

5. Inspect the solder joints of the two “original” leads on the circuit board copper side. If they are not shiny, reheat them and apply additional solder if necessary.

uTECHNICAL INFORMATION

Electrical

Pixel pitch 0.3mm X 0.3mm Horizontal frequency 30KHz to 62KHz (Automatically) Vertical frequency 50Hz to 85Hz (Automatically) Operating temperature 10-40°C / 50-104°F Operating humidity 8-80%

Mechanical

Cabinet Molded Plastic Cabinet with attachable tilt & swivel base Dimension (set with packing) 502(H) X 502(W) X 242(D) mm Weight(net) 4.5 Kg

Controls

Power Switch OSD control

GENERAL INFORMATION

This TFT LCD monitor automatically scans all horizontal frequencies from 30KHz to 62KHz, and all vertical frequencies from 50Hz to 85Hz. This TFT LCD monitor supports IBM PC, PC/XT, PC/AT, personal System/2 (PS/2), Apple Macintosh, and compatible users crisp text and vivid color graphics display when using the following graphics adapters : (VGA, Super VGA, VESA and XGA and Apple Macintosh Video Card). And so, this TFT LCD monitor has a maximum horizontal resolution of 1024 dots and a maximum vertical resolution of 768 lines for superior clarity of display. By accepting analog signal inputs which level is zero to 0.7 Volts. This TFT LCD monitor can display and 262, 144 colors depending on the graphics adapter and software being used.(available used to 8 bit panel is 16.7M colors)

Abbreviations

ADJ AFC H.sync OSC P.S.U PWA R.G.B V.sync

Adjustment Automatic Frequency Control Horizontal Synchronization Oscillator Power Supply Unit Printed Circuit Board Wiring Assembly Red, Green, Blue Vertical Synchronization

PIN CONNECTOR

Pin Signal

1 Red 2 Green 3 Blue 4 GND 5 GND 6 GND - Red 7 GND - Green 8 GND - Blue

9 +5Vdc 10 GND - H.Sync 11 GND - V.Sync 12 Bi-directional Data (SDA) 13 Horizontal Sync 14 Vertical Sync (VCLK) 15 Data clock (SCL)

Arrangement of 15-pin D-sub connector

CAUTION FOR ADJUSTMENT AND REPAIR

w The white balance adjustment has been done by a color analyzer in factroy. The adjustment proce-

dure, described in the service manual is made by a visual check.

w Allow 20 minutes warm-up time for the display before checking or adjusting only electrical specifica-

tion or function.

w Reform the leadwire after any repair work.

OPERATION & ADJUSTMENT

Control Panel

w Move cursor to the right window on the OSD window. w Increase the value of any selected function.

w Move cursor to the left window on the OSD window. w Decrease the value of any selected function.

w Launch OSD(On-Screen Display) MENU window.

w Move cursor to the high window on the OSD window. w Increase the value of V.center.

w Move cursor to the low window on the OSD window. w Decrease the value of V.center.

Key Process

OPERATION & ADJUSTMENT

Start

w When you choose the icon on the OSD window, you can exit the OSD screen.

Hot Key

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