Daewoo 526X Schematic

Service Manual

XGA COLOR MONITOR Model : 526X

D AEW OO ELECTR ONICS CO., LTD.

◆ Electrostatically Sensitive (ES) Devices

Some semiconductor (solid state) devices can be damaged easily by static electricity. Such components are commonly called Electrostatically Sensitive (ES) Devices. The typical examples of 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, wipe off any electrostatic charge on your body by touching any 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 testing conditions.

2. After removing the electrical assembly equipped with ES devices, place the assembly on a conductive surface such as aluminum foil to prevent electrostatic charge buildup or exposure to the assembly.

3. Only use a grounded-tip soldering iron to solder or unsolder ES devices.

4. Only use an anti-static type solder removal device. Some solder removal devices not classified as “antistatic” can generate enough electrical charges to damage ES devices.

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 replacement ES devices, touch the protective material to the chassis or circuit assembly into which the device will be installed.

8. Minimize bodily movements when handling unpackaged replacement ES devices. (Otherwise harmful motion such as the brushing together clothes fabric or the lifting your foot from a carpeted floor can generate enough static electricity to damage 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 between 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 until the solder flows onto and around both the component lead and the foil.

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 ends 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 ensure 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 then 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

CDT Size 15-inch Diagonal visible image area 14-inch Dot Pitch 0.28 mm Synchronization Horizontal 30 - 54 KHz

Vertical 50 - 160 Hz Plug and Play DDC1/2B/CI Power Saving EPA, VESA DPMS, Nutek Compliant Power Source 100-240 Vac, 50/60Hz (Free Voltage) Power Consumption 70W Dimension-W x H x D 360 x 381 x 389mm (set with stand) Weight-unpacked(lbs/Kg) 25.1/11.4 Operating Temperature 10 ~ 40°C /50 ~ 104°F

This color monitor automatically scans all horizontal frequencies from 30KHz to 54KHz, and all vertical frequencies from 50Hz to 160Hz. 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 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 color monitor can display and unlimited palette of colors depending on the graphics adapter and software being used.

◆ Abbreviations

GENERAL INFORMATION

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 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)

• Degaussing is always required when adjusting purity or convergence.

• The white balance adjustment has been done by a color analyzer in factroy. 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 CONNECTOR

CAUTIONS FOR ADJUSTMENT AND REPAIR

OPERATION AND ADJUSTMENT

Control Panel

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

• Select a sub Menu & function.

• Move a sub Menu & function.

• Increase the value of any selected function.

• Adjust the contrast directly when there is no OSD.

• Move a sub Menu & function.

• Decrease the value of any selected function.

• Adjust the brightness directly when there is no OSD.

SELECT

ADJUST

SELECT

Key Process

•

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

SELECT

OSD OFF

MENUMENU

OSD Functions

ICON CONTROL FUNCTIONS

Adjust the pin corner bottom when the bottom sides of the screen are bowed.

B. PIN CORNER

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

T. PIN BALANCE

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

B. PIN BALANCE

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

Adjust the pin corner top when the top sides of the screen are bowed.

T. PIN CORNER

PARALLELOGRAM

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

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

PIN BALANCE

TRAPEZOID

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

PINCUSHION

Adjust the display height (vertical size).

Adjust the vertical linearity.

V. LINEARITY

V.SIZE

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

Adjust the display width (horizontal size).

H.SIZE

V. POSITION

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

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

COLOR TEMP

Reset the screen to the Factory Preset Display Settings.

RECALL

ICON CONTROL FUNCTIONS

Display horizontal & vertical frequency and polarity.

STATUS

Adjust the rotation when the screen is tilted left or right (Optional).

ROTATION

Adjust the vertical picture moire cancellation.

V. MOIRE

Adjust the horizontal picture moire cancellation.

H. MOIRE

Degaussing keeps the monitor free from unwanted magnetism that can result in color impurity.

DEGAUSS

Adjust the blue bias.

BLUE BIAS

Select language for OSD (5 languages).

LANGUAGE

Adjust the green bias.

GREEN BIAS

Adjust the red bias.

RED BIAS

Adjust the red gain.

Adjust the green gain.

Adjust the blue gain.

RED GAIN

GREEN GAIN

BLUE GAIN

ALIGNMENT PROCEDURE

◆ Standard Adjustment Conditions

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

2. Aging : Take at least 20 minutes warm-up time.

3. Signals

Video : Analog 0.7Vpp 75Ω terminal positive polarity Synchronizing : TTL level Negative/Positive Separate Deflection frequency

Horizontal Frequency : 30KHz - 54KHz Vertical Frequency : 50Hz - 160Hz

◆ Pre-Adjustment

1. B+ Adjustment Adjust 6.15Vdc ± 0.05Vdc between P503 and ground at 31.5KHz mode, varying VR001. Adjust -150Vdc ± 0.5Vdc between P504 and ground at 31.5KHz mode, varying VR501.

◆ Method to launch the factory mode

Step 1. Push the menu button. Step 2. Push the menu button and plus control button ( + ) for 5 times in same time.

◆ Main Adjustment

1. Setting the Controls

Set the value of items as following.

Contrast : Max.(OSD value up to MAX) Brightness : Center(Set the OSD value to center)

2. H.size, V.size, H.phase, V.position, Pincushion, Trapezoid Receive the cross hatch pattern of Factory preset mode. H.size, V.size, H.phase, V.position, Pincushion, Trapezoid 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 1024 X 768 (48KHz, 60Hz) (c) Adjust the Focus control of FBT to obtain best Focus.

4. Geometric Distortion Adjustment. (a) Receive the cross hatch pattern of factory preset mode. (b) Pincushion, Trapezoid are adjusted the best geometric status.

5. White Balance Adjustment (a) Select 9300°K on the OSD Menu. (b) Receive a full white pattern of 54KHz mode signal by using the signal generator. (c) Set the brightness control to the maximum, the contrast control to the maximum. (d) Cut off the FBT screen VR. (e) Receive all the black patterns. The luminance of the screen should be 0.5~1.0 Ft-L by using Screen

VR.

(f) Select the R-BIAS, G-BIAS and B-BIAS on the control menu and adjust the +/– key to get the color

coordinates in x=0.281 ± 0.015, y=0.311± 0.015. (g) Receive a full white pattern. Adjust the brightness value to the center. (h) Select the R-GAIN and B-GAIN and adjust the +/– key to get the color coordinates in x=0.281 ±

0.015, y=0.311 ± 0.015. (i) Adjust the ABL control to get the screen luminance to 30 Ft/L (a full white pattern over 30 Ft/L) (j) 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 coorinates in x=0.281, y=0.311. Make sure that the coordinates is in range.

(k) Select 6550°K on the OSD Menu and set the color coordinates in x=0.313, y=0.329 at the

maximum contrast control and center brightness control

(l) Check if a full white pattern is over 30Ft/L.

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