Daewoo 715B User manual

DAEWOO ELECTRONICS CO., LTD.
http : //svc.dwe.co.kr
Service Manual
XGA COLOR MONITOR
Model : 715B

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)
8
• 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
Adjust the horizontal linearity.
H. LINEARITY
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

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
Choose different preset color temperatures or set your own customized color parameters.
Adjust the red gain.
Adjust the green gain.
Adjust the blue gain.
COLOR TEMP
RED GAIN
GREEN GAIN
BLUE GAIN

13
◆ Standard Adjustment Conditions
1. Power source voltage : AC 120V, 60Hz/AC 220V, 50Hz.
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/Composite
Deflection frequency
Horizontal Frequency : 30KHz - 70KHz
Vertical Frequency : 50Hz - 160Hz
◆ Pre-Adjustment
1. High Voltage Adjustment
Adjust 25.8K Vdc between Anode cap and ground at a cross hatch pattern of 60KHz by using VR 601.
2. H.Size Adjustment
(a) Receive a cross hatch pattern of 60KHz
(b) Set the H-Size control to the maximum on OSD menu.
◆ 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 100)
Brightness : Center (Set the OSD value to 50)
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 60KHz mode signal.
(c) Adjust the Focus control of FBT to obtain best Focus (static focus and Dynamic focus).
4. Geometric Distortion Adjustment
(a) Receive the cross hatch pattern of VGA mode signal by using the signal generator.
(b) Pin balance, Parallelogram are adjusted the best geometric status.
(c) Repeat the adjustment at each mode.
5. White Balance Adjustment
(a) Receive a full white pattern of 60KHz mode.
(b) Set the bright control and contrast control to the maximum and receive the all black pattern.
(c) Adjust the G1 control in Factory mode to 0.8 Ft/L.
(d) Select the R, G, B Bias on the OSD menu and adjust the +/– key to get the color coordinates in
X=0.281, Y=0.311.
(e) If the screen luminosity is changed, repeat (c) & (d) to get the 0.8 Ft/L screen luminosity.
(f) Set the brightness control to the center and contrast control to the maximum.
(g) Receive a full white pattern.
ALIGNMENT PROCEDURE

14
(h) Select the R, G, B gain on the OSD menu and adjust the +/– key to get the color coordinates in
X=0.281±0.02, Y=0.311±0.02.
(i) Adjust the sub contrast (ABL) control to get the screen luminosity to 30.0 Ft/L.
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 angles 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 the display.
(f) Vertical green and red lines are converged by varying the angle between the two tabs of the 6-pole
magnets.
(g) Horizontal green and red lines are converged by varying the tabs together and keeping the angle
between them constant.

15
TROUBLESHOOTING HINTS
1. No Character
Are the
Contrast &
Brightness Controls
maximum
Change the Contrast &
Brightness control to
maximum
No Raster Refer to
No Raster
Check the peripheral circuit
of CRT Board
Check the video output
circuit and IC802 (pin 4, 10, 12)
and their ambient circuit
Trouble in 12Vdc line
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 45Vpp
No
No
Is CRT
Cathode (Rk, Gk, Bk)
signal level
normal?
Is the
output signal of the
(pin 21, 24, 26) pre-amp
(IC801, KA2500)
normal?
Is clamping
pulse (pin 18 of IC801)
normal?
Is 12Vdc line
normal?
Is input signal
normal?
Trouble in IC801 and
its ambient circuit

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

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 or
Abnormal picture
Is
– 13V DC line
correct? Check PWR – 13V
ambient circuit.
No
Yes
Is
the output
waveform of IC401
(pin 5) normal?
Trouble in V.Sync line
or IC501 failure.
Yes
No
45Vp-p
Is the
output pulse
of IC501 (pin 4)
normal?
Yes
No
Check V.DY
and ambient circuit.
Check the IC401
or ambient circuit.

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

23
7-1. Dynamic Focus
Focus is poor
Is the
waveform of the
DF pin in FBT
correct?
ORION : 300V 150V
1. Check the CRT socket
or connector wire
2. Trouble in FBT or CRT
1. Check the waveform of
the pin 4 of FBT.
2. Check D705
1. Check the 12V DC line.
2. Check Q703, Q704
* Check after adjusting the static focus
finely by VR in FBT
DF
waveform
FVH
FVH FVV
FVV
No
Is the
base voltage of
the Q703 about
12V?
Yes
Yes
Yes
Is the
waveform of
the pin 8 in IC501
correct?
Yes
No
No
Trouble in Q701, Q702
Trouble in IC501 or C523
No
DF
waveform
4.5V
2V
0V
0.8V
Is the
cathode voltage
of the D705
about 700V?

24
8. Convergence
Is
convergence
on the center area
bad?
Is
convergence on the
fringe area bad?
Adjust static
convergence
Refer to
Adjustment
procedure of
convergence
Yes
Adjust D.Y
Location
Yes
No
Poor convergence

25
9. Abnormal Picture
9-1. Horizontal Size
Is the HV 25.8KV? No
Yes
Check the IC501 and R503, C507
Abnormal
H.Size
Adjust the HV VR601

26
9-2. Vertical Size
Is
changeable the
DC voltage of
IC401 pin 1?
Check the IC401
and its
ambient circuit
Check the IC501 and
its ambient circuit
No
No
Trouble V.OSC/
Deflection Circuit
Refer to V.OSC/Deflection circuit
Yes
Is
the 3.5Vdc of pin
4 of the IC501? Yes
Abnormal
V.Size
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