Daewoo 531X User Manual

D AEW OO ELECTR ONICS CO., LTD.

http : //svc.dwe .co.kr

Service Manual

XGA COLOR MONITOR

Model : 531X

September, 2000

15

TROUBLESHOOTING HINTS

1. No Character

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 14, 16, 18) pre-amp

IC801, normal?

Is blanking

pulse (pin 20 of IC801)

normal?

Is 12V line

normal?

Is input signal

normal?

Trouble in IC801 and

its ambient circuit

5Vp-p

Are the Contrast &

Brightness Controls in

OSD menu

maximum?

16

2. No Raster

Trouble in
power supply
circuit

Trouble in power
supply circuit

Trouble in G1
line

Trouble in FBT or its
pin4 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

Yes

No

No

No

No

Yes

No

Yes

Yes

Yes

Yes

No

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

-60V?

Is 100Vdc

line normal?

Does

the Brightness control

make screen

bright?

Is CRT

G2 (screen) voltage

about 730V?

Trouble in
CRT

Raster OK

Yes

Yes

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,TDA9210)

pin 14, 16,18 all

normal?

Check video signal
cable or video card.

Trouble in IC801 or its
ambient circuit

Trouble in
video output
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 IC204
(pin 13, 14, 15)

normal?

Trouble in
Heater voltage
line.

Refer to trouble in P.S.U

Troubie in
IC803 or its
ambient circuit

Trouble in IC204
and its ambient
circuit

One color is
missing

Refer to Missing Color

No

No

Yes

Yes

Yes

Yes

No

MODE B+ Voltage
VGA 60Vdc
Super VGA

72Vdc

54KHz 110Vdc

19

5. Horizontal Output Circuit

Is the

B+line voltage

over 50V?

Is the H-out

waveform of IC501

normal?

Trouble in IC501

Trouble in Horizontal

output circuit

(No Raster

Yes

No

Is the Collector

wave form of

Q504 normal?

Yes

Yes

Yes

Trouble in Q505

No

No

No

Trouble in Q505 and

its ambient circuit.

3V

0V

50V

Is the Drain

waveform of

Q507 normal?

Trouble in 50V

Trouble in Q506

0V

0V

70V

20

6. Unstable Picture

6-1. Horizontal

Unstable

picture

Is the

pulse of pin 26 of

the IC501

correct?

Trouble in IC501
or its ambient
circuit

Is the

pulse of pin 28 of

the IC201

correct?

Check IC501 and
its ambient circuit

No

No

No

Yes

Yes

Is the

input H.Sync

correct?

Check IC201 and
its ambient circuit

Yes

Trouble in Signal Cable
or 15P D-Sub Connector

5Vpp

21

6-2. Vertical

Unstable

picture

Is the

12V,-12Vdc

line voltage is

correct?

Refer to P. S. U

Is the

pulse of pin 6 of

the IC401

correct?

Trouble in
vertical D. Y

No

No

No

Yes

Yes

Is the output

of pin 8 of IC501

all normal?

Check IC401 and
its ambient circuit

Yes

Check the IC501 and
its ambient circuit

50Vp-p

40V

-10V