Daewoo 531X-3 Service Manual page 10

2. No Raster
No Raster
Is CRT No
heater red-hot?
Yes
Turn the Brightness
& Contrast control
to set Maximum
Yes
Is whole
screen bright?
Yes
Check
G1 voltage about
-70V?
Yes
Is CRT
G2 (screen) voltage
about 480V?
Yes
Is 80Vdc
line normal?
Yes
Does
the Brightness control
make screen
bright?
Yes
Raster OK
Is Heater
Yes
Trouble in
Voltage (CRT PWA)
CRT
about 6V?
No
Trouble in
Refer to trouble in
power supply
PSU.
circuit
No
Trouble in power
supply circuit
No
Trouble in G1
line of main PWA
No
Trouble in FBT or its
pin4 ambient circuit
Trouble in 80Vdc
No
Refer to trouble
line of power
in P.S.U
supply unit
No
High Voltage
trouble in FBT
16
3. A Missing Color
One color is
missing
Is input signal
normal?
0.7Vpp
Yes
Is the
output of pre-amp
(IC801,LM1238)
pin 19,20,21 all
normal?
Yes
CRT
No
Cathode (Rk, Gk, Bk)
is normal?
RK, GK, BK
About 40V p-p
Yes
Each grid (G1, G2)
voltage normal?
Yes
Replace CRT
No
Check video signal
cable or video card.
No
Trouble in IC801 or its
ambient circuit
Is video
No
output IC802
Trouble in
waveform normal?
video output
IC802
or ambient
Yes
Trouble in 80Vdc
line
No
Trouble in G1,G2 line
17