Service manual

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?