Daewoo 901D Schematic

Service Manual

XGA COLOR MONITOR Model : 901D

DAEWOO ELECTRONICS CO., LTD OVERSEAS SERVICE DEPT.

CONTENTS

SAFETY PRECAUTIONS 1 GENERAL SAFETY INFORMATION 2 SERVICING PRECAUTIONS 3 TECHNICAL INFORMATION 6 GENERAL INFORMATION 7 PIN CONNECTOR 8 CAUTIONS FOR ADJUSTMENT AND REPAIR 8 OPERATION & ADJUSTMENT 9 ALIGNMENT PROCEDURE 17 TROUBLESHOOTING HINTS 19 BLOCK DIAGRAM 35 PCB LAYOUT 36 SCHEMATIC DIAGRAM 42 EXPLODED VIEW & MECHANICAL PARTS LIST 44 INFORMATION OF PART DESCRIPTION 45 ELECTRICAL PARTS LIST 46

SAFETY PRECAUTIONS

Safety Check

Care should be taken while servicing this analog color display because of the high voltages used in the deflection circuits. These voltages are exposed in such areas as the associated flyback and yoke circuits.

Fire & Shock Hazard

• Insert an isolation transformer between the analog color display and AC power line before servicing chassis.

• 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.

• All the protective devices must be reinstalled per original design.

• 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

Picture tube 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 picture tubes.

X-Radiation

IMPORT ANT SAFETY NOTICE: There are special components used in analog 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.

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.

WARNING: The only potential source of X-Radiation is the picture tube. However when the high voltage circuitry

is operating properly, there is no possibility of an X-Radiation problem. The basic precaution which must be exercised is to keep the high voltage at the following factory recommended level.

NOTE: It is important to use an accurate, periodically calibrated high voltage meter.

•

To measure the high voltage, use a high-impedance high-voltage meter. Connect(-) to chassis and (+) to the CRT anode button.

• Turn the Contrast & brightness control fully counterclockwise.

• Measure the high voltage. The high voltage meter should indicate the following factory recommended level.

• If the upper meter indication exceeds the maximum level, immediate service is required to prevent the possibility of premature component failure.

• To prevent X-Radiation possibility, it is essential to use the specified picture tube.

• The normal high voltage is 26.5KV or below, and must not exceed 29KV at zero beam current at rated voltage.

GENERAL SAFETY INFORMATION

Warning: This product includes critical mechanical and electrical parts which are essential for x radiation safety. For continued safety , replace critical components indicated in the service manual only with exact replacement parts given in the parts list. Operating high voltage for this product is 29Kv at minimum brightness. Refer to service manual for measurement procedures and proper service adjustments.

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 V oltage Warning And Critical Component Warning Label Following warning label is on the CRT PWB shield case inside the unit.

SERVICING PRECAUTIONS

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.

d. Discharging the picture tube anode.

2. Test high voltage only by measuring it with an appropriate high voltage meter or other voltage measuring device (DVM, FETVOM. etc.) equipped with a suitable high voltage probe. Do not test high voltage by “drawing an arc”.

3. Discharge the picture tube anode only by: (a) first connecting one end of an insulated clip lead to the degaussing or line grounding system shield at the point where the picture tube socket ground lead is connected, and then (b) touching the other end of the insulated clip lead to the picture tube anode button, using an insulating handle to avoid personal contact with high voltage.

4. Do not any spray chemicals on or near this instrument or any or its assemblies.

5. 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) Acetone and 90% (by volume) isopropyl alcohol (90%-99% strength).

6. Do not defeat any plug/socket B+ voltage interlocks with which instruments covered by this service manual might be equipped.

7. 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.

8. 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.

9. Use only the test fixtures specified in this service manual with this instrument.

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.

CAUTION: A wrong part substitution or incorrect polarity installation of electrolytic capacitors may result in

a explosion hazard.

CAUTION: This is a flammable mixture. Unless specified otherwise in this service manual, lubrication of

contacts is not required.

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

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.

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

precautions.

CAUTION: Work quickly to avoid overheating the circuit board printed foil.

FIGURE 1. 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.

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.

TECHNICAL INFORMATION

Picture Tube

Type : 19-inch, Flat Square Tube type (18-inch, viewing area) Dot Pitch : 0.26mm Face Treatment : Anti-reflect / Anti-static

Video

Input Signal : R.G.B Analog Pixel Clock : 203 MHz Input Sync : TTL, separate negative / positive

H+V Sync. on Green, negative

Composite H+V Sync. negative / positive

Scan Frequency

Horizontal : 30-95 KHz(automatic)

Vertical : 50-160 Hz(automatic)

Max. Resolution

1600 dots X 1200 lines (at 75Hz)

Power Source

Free Voltage (100-240 Vac, 50/60Hz)

Display Area

Standard Display Area : 350mm(H)X262mm(V) Full Screen Size : 365.8mm(H)X274.3mm(V)

Power Consumption

Max. 130W

Dimension

466(W)X474.5(H)X482(D)mm (set with stand)

Weight (Net/Gross)

23.5/27.5 kg

Operating Environment

Temperature : 10~40°C/50~104°F Relative Humidity : 8~80%

Storage Environment

Temperature : -20~45°C/-4~1 13°F Relative Humidity : 5~90%

State Recovery Time Power LED

On None Green

Stand-by

3 seconds

Green : 1 second

Suspend Amber : 0.5 second

Off - Amber

GENERAL INFORMATION

This color monitor automatically scans all horizontal frequencies from 30KHz to 95KHz, and all vertical frequencies from 50Hz to 160Hz. This color monitor adopted the OSD (On Screen Display), it shows the sync polarity and frequency and it provides that easily adjust control. This color 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, 8514/A, Super VGA, VESA and XGA and Apple Macintosh Video Card). And so, this color monitor has a maximum horizontal resolution of 1600 dots and a maximum vertical resolution of 1200 lines for superior clarity of display.

By accepting analog signal inputs which level is zero to 0.7 Volts. This color monitor can display and unlimited palette of colors depending on the graphics adapter and software being used.

Abbreviations

ADJ Adjustment AFC Automatic Frequency Control CRT Cathode Ray Tube Def Deflection D.Y Deflection Yoke FBT Flyback Transformer H.SYNC Horizontal Synchronization OSC Oscillator P.S.U Power Supply Unit PWA Printed Circuit Board Wiring Assembly R.G.B Red, Green, Blue V.Sync Vertical Synchronization

PIN CONNECTOR

CAUTIONS FOR ADJUSTMENT AND REP AIR

• Degaussing is always required when adjusting purity or convergence.

• The white balance adjustment has been done by a color analyzer in factory. The adjustment procedure, described in the service manual is made by a visual check.

• Allow 20 minutes warm-up time for the display before checking or adjusting only electrical specification or function.

• Reform the leadwire after any repair work.

Caution For Servicing

• In case of servicing or replacing CRT, high voltage sometimes remains in the anode of the CRT. Completely discharge high voltage before servicing or replacing CRT to prevent a shock to the serviceman.

Arrangement of 15-pin D-sub 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 1 1 GND - V.Sync 12 Bi-directional Data (SDA) 13 Horizontal Sync 14 Vertical Sync (VCLK) 15 Data Clock (SCL)

610

OPERA TION & ADJUSTMENT

• Launch OSD(On-Screen Display) MENU window

• Move cursor to the FUNCTION window from the MENU window

• Select a FUNCTION among 8 FUNCTIONs on the FUNCTION

window

• Move cursor to the next MENU on the MENU window

• Move cursor to the next FUNCTION on each FUNCTION window

• Increase the value of any selected FUNCTION

• Increase the contrast directly when OSD is not displayed

• Move cursor to the previous MENU on the MENU window

• Move cursor to the previous FUNCTION on each FUNCTION

window

• Decrease the value of any selected FUNCTION

• Decrease the contrast directly when OSD is not displayed

ADJUSTMENT KEY

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

ADJUSTMENT PROCESS

OSD MENU

MENU WINDOW

FUNCTION WINDOW

ADJUSTMENT WINDOW

CURSOR

Adjust the contrast of image, the difference between light and dark areas on the screen. Range : 0 -100 %

Adjust the brightness of the entire image.

Adjust the position of the display horizontally (left or right).

Adjust the display width (horizontal size).

Adjust the position of the display vertically (up or down).

Adjust the display height (vertical size).

Main Menu Functions

Return to the Main Menu Window.

Adjust the display width & height at the same time.

Adjust the rotation when the screen is tilted left or right.

• Image turns to by .

Adjust the left and right margins for more convex or more concave margins.

• Image turns to by .

Adjust the trapezoid of the screen by moving the lines inward or outward.

• Image turns to by .

Adjust the parallelogram when the screen is leaning left or right.

• Image turns to by .

Adjust the side balance when the sides of the screen are bowed towards left or right.

• Image turns to by .

Adjust the pin S control when the sides of the screen are in a S shape.

• Image turns to by .

Adjust the pin W control when the sides of the screen are in a W shape.

• Image turns to by .

Geometry Menu Functions

Return to the Geometry Menu Window.

Choose different preset color temperatures or set your own customized color parameters.

Adjust the green gain.

Adjust the blue gain.

Adjust the red bias.

Adjust the green bias.

Adjust the blue bias.

Adjust the red gain.

Color Menu Functions

Return to the Color Menu Window.

Display horizontal & vertical frequency and polarity.

YES : VESA DPMS operation. NO : NO DPMS operation.

Select language for OSD.

Select a Input Signaling Type between D-Sub and BNC connector.

Utility Menu Functions

Reset the screen to the Factory Preset Display Settings.

Return to the Utility Menu Window.

Degauss the display and restore image quality.

Display a RGB Color Bar to determine whether the screen color is expressed normally or not.

Adjust the vertical linearity.

Adjust the horizontal linearity.

Adjust the horizontal picture moire cancellation.

Adjust the vertical picture moire cancellation.

Special Menu Functions

Adjust the focus image.

Return to the Special Menu Window.

Self Diagnosis

No Signal screen is displayed when the D-Sub signal connector is not connected or the status of the monitor is on DPMS mode.

Out of Range screen is displayed when the applied frequency is under or over normal range.

Normal range H : 30-95 KHz V : 50-160 Hz

When the monitor doesn’t display, if you press any key, Self Diagnosis screen is displayed. Self Diagnosis function checks if the status of the monitor is No Signal or Out of range.

ALIGNMENT PROCEDURE

Standard Adjustment Conditions

1. Power source voltage : AC 100 - 240Vac, 50/60Hz.

2. Aging : Take at least 15 minutes warm-up time.

3. Signals. Video : Analog 0.7Vpp 75Ω terminal positive polarity

Synchronizing : H+V Sync on Green : 0.286Vpp ± 5% (Negative)

Composite H+V Sync : 1.0Vpp ~5.0Vpp (Positive / Negative) Separate H, V Sync : TTL Level (Positive / Negative)

Deflection frequency

Horizontal Frequency : 30KHz - 95KHz Vertical Frequency : 50Hz - 160Hz

Pre-Adjustment

1. B+ Adjustment Adjust VR151 for 1 18Vdc between P6 and ground at 91KHz mode.

Main Adjustment

1. Setting the Controls Set contrast and brightness in Control Menu unless otherwise specified. Contrast : Max. Brightness : Center

2. H.size, H.phase, V.size, H.phase, Side Pincushion, Pincushion S, Pincushion W, Trapezoid, Parallelogram, Rotation, Pin Balance, H.Linearity, V.Linearity Receive the cross hatch pattern of Factory preset mode.

H.size, H.phase, V.size, H.phase, Side Pincushion, Pincushion S, Pincushion W, Trapezoid, Parallelogram, Rotation, Pin Balance, H.Linearity, V.Linearity controls are adjusted at each mode. In Factory , Auto Alignment was done at each mode. Therefore, Factory preset mode has it’s own value according to each control.

3. Focus (a) Set brightness control to Center and contrast control to Max. (b) Receive all “H” character pattern of 91KHz mode signal. (c) Adjust the Static Focus VR to obtain best H.Focus. (d) Adjust the Dynamic Focus VR to obtain best V .Focus. (e) If the H/V Focus is not satisfactory, readjust the Static / Dynamic Focus.

4. White Balance Adjustment. (a) Select 9300°K on the OSD Menu. (b) Receive a full white pattern of 91KHz. (c) Select the brightness and the contrast controls to the maximum and each R.G.B. Gain/Bias controls to the

initial values. (d)Cut off the FBT screen VR. (e)Receive all the black patterns and adjust FBT screen VR the screen luminosity to be approx. 0.5 ±0.1 Ft/L. (f) Select the R - BIAS, G - BIAS and B - BIAS on the OSD menu and adjust the DATA +/– key to get the color

coordinates in X=0.281, Y=0.311. (g)Adjust screen VR the screen luminosity to be approx. 0.5 ±0.1 Ft/L. (h)Select the brightness control to the center (50). (i) Receive a G.Signal. (j) Select the G - GAIN on the OSD menu and adjust the DATA +/– key to get the screen luminosity up to 26

Ft/L. (k) Select the B - GAIN and adjust the DATA +/– key to get the color coordinates in Y=0.311± 0.015. (l) Select the R - GAIN and adjust the DATA +/– key to get the color coordinates in X=0.281±0.015.

(m) Check if the x,y coordinates of color analyzer is in x=0.281 ± 0.015, y=0.311 ±0.015.

If the color coordinates is out of range, adjust the R.G.B Bias & Gain to get the coordinates in X=0.281, Y=0.31 1. Make sure that the coordinates is in range by using contrast control.

(n) Check the screen luminosity up to 30 Ft/L in brightness & contrast control to the maximum. If the screen

luminosity is not satisfactory, readjust the white balance.

TROUBLESHOOTING HINTS

1. No Character

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