Daewoo 526X User manual

DAEWOO ELECTRONICS CO., LTD.
http : //svc.dwe.co.kr
Service Manual
XGA COLOR MONITOR
Model : 526X

4
◆ 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 “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 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.
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.

5
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.

6
◆ 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
7
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

8
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
1
6
15
10

9
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.
MENU
SELECT ADJUST
MENU
SELECT

10
Key Process
•When you choose the icon on the OSD window, you can exit the OSD screen.
MENU
SELECT
OSD OFF
MENU
MENUMENU

11
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

12
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 75Ωterminal 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.
13

14
6. Static Convergence Adjustment
(a) Apply a magenta cross hatch pattern on display.
(b) Adjust the focus from the best over all focus on the display.
Also adjust the brightness to the desired condition.
(c) Vertical red and blue lines are converged by varying the angle between the two tabs of the 4-pole
magnets.
(d) Horizontal red and blue lines are converged by varying the tabs together, keeping the angle between
them constant.
(e) Apply a yellow cross hatch pattern on display.
(f) Vertical green and red lines are converged by barying the angle between the two tabs of the 6-pole
magnets.
(g) Horizontal green and red lines are converged by varying the tabs together, keeping the angle
between them constant.

15
TROUBLESHOOTING HINTS
1. No Character
Are the Contrast &
Brightness Controls in
OSD menu
maximum?
Change the Contrast &
Brightness control value to
maximum
No Raster Refer to
No Raster
Check the peripheral circuit
of CRT
Check the video output
circuit and its ambient circuit
Trouble in 12V line
of the Main PWB
Check the clamping pulse
circuit
Check the signal cable
No Character
Is whole
screen bright?
Yes
Yes
Yes
Yes
Yes
No
No
No
No
No
Yes
Yes
Rk, Gk, Bk
About 30~35Vpp
No
No
Is CRT
Cathode (Rk, Gk, Bk)
signal level
normal?
Is the
output signal of the
(pin 21,24,26) pre-amp
IC801, normal?
Is clamping
pulse (pin 18 of IC801)
normal?
Is 12V line
normal?
Is input signal
normal?
Trouble in IC801 and
its ambient circuit
5Vp-p

16
2. No Raster
Trouble in
power supply
circuit
Trouble in power
supply circuit
Trouble in G1
line
Trouble in FBT or its
pin 4 ambient circuit
High Voltage
trouble in FBT
Trouble in 100Vdc
line of power
supply unit
Refer to trouble
in P.S.U
Refer to trouble in
power supply unit.
Is CRT
heater red-hot?
No
No
No
No
No
No
No
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Is Heater
Voltage (CRT PWB)
about 6V?
Turn the Brightness
& Contrast control
to set Maximum
No Raster
Is whole
screen bright?
Check
G1 voltage about
-40V?
Is 100Vdc
line normal?
Does
the Brightness
control make screen
bright?
Is CRT
G2 (screen) voltage
about 500V?
Trouble in
CRT
Trouble in FBT

17
3. A Missing Color
Is input signal
normal?
One color is
missing
CRT
Cathode (Rk, Gk, Bk)
is normal?
Is video
output IC802 waveform
normal?
Each grid (G1, G2)
voltage normal?
Is the
output of pre-amp
(IC801, KA2500)
pin 21, 24, 26 all
normal?
Check video signal
cable or video card.
Trouble in IC801 or its
ambient circuit
Trouble in
video output
circuit, IC802
or ambient
Trouble in 100Vdc line
Trouble in G1,G2 line
Replace CRT
No
No
No No
No
Yes
Yes Yes
Yes
Yes
RK, GK, BK
About 40V p-p
0.7Vpp

18
4. Abnormal OSD Font
Is menu
key selected?
Is OSD Font
exist?
* If menu key selected.
Is Heater
Voltage about 6V?
Abnormal OSD Font
Is the
output of IC803
(pin 12,13, 14)
normal?
Trouble in
Heater voltage
line.
Refer to trouble in P.S.U
Troubie in
IC803 or its
ambient circuit
Trouble in IC803
and its ambient
circuit
One color is
missing
Refer to Missing Color
No
No
Yes
Yes
Yes
Yes
No

MODE B+ Voltage
VGA 72Vdc
Super VGA 86Vdc
54KHz 124Vdc
19
5. Horizontal Output Circuit
Is the
B+line voltage
over 175V?
Is the H-out
waveform of IC501
normal? Trouble in IC501
Trouble in Horizontal
output circuit
(No Raster)
Yes
No
Is the Gate wave
form of
Q553 normal?
Yes
Yes
Yes
Trouble in Q553
Trouble in Q551, Q552
No
No
No
Trouble in Q554 and
its ambient circuit.
10V
0V
11V
0V
66V
Is the Drain
waveform of
Q553 normal?
Trouble in 175V line.

20
6. Unstable Picture
6-1. Horizontal
Unstable
picture
Is H.Sync
input pin of IC501
correct?
Check H.Sync Out of
Micom or its ambient
circuits.
Yes
No
Trouble in IC501

21
6-2. Vertical
Unstable
picture
Is the
12V,-12Vdc
line voltage is
correct? Refer to P. S. U
Is the
pulse of pin 5 of
the IC401
correct?
Trouble in
vertical D. Y
No
No
No
Yes
Yes
Is the output
of pin 4 of IC501
all normal? Check IC401 and
its ambient circuit
Yes
Check the IC501 and
its ambient circuit
50Vp-p
40V
-10V

22
7. Focus
Monitor remains
unfocused
Check
Focus VR in
FBT
Is
focus
acceptable?
Trouble in Focus
circuit (FBT)
Yes OK
No