Daewoo 715B Service Manual

D AEW OO ELECTR ONICS CO., LTD.

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)

• 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 dischar ge

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 REP AIR

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

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

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

◆ 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

(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.

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.

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

Rk, Gk, Bk

About 45Vpp

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

2. No Raster

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?

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

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

Yes

Yes Yes

Yes

RK, GK, BK

About 40V p-p

0.7Vpp

+ 23 hidden pages

Daewoo 715B Service Manual

Specifications and Main Features

Frequently Asked Questions

User Manual