Service manual

TROUBLESHOOTING HINTS
15
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 IC803 (pin 1, 3, 5)
and their ambient circuit
Trouble in 12V DC 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 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 12V DC line
normal?
Is input signal
normal?
Trouble in IC801 and
its ambient circuit