Technical information

1514
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 5V line
of the Main PWA
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 19,20,21) pre-amp
IC801(LM1238) normal?
Is blanking
pulse (pin 23 of IC801)
normal?
Is 5V line
normal?
Is input signal
normal?
Trouble in IC801 and
its ambient circuit
Are the Contrast &
Brightness Controls in
OSD menu
maximum?
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.
(c) Vertical red and blue lines are converged by varying the angle between the two tabs of the 4-pole
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 display.
(f) Vertical green and red lines are converged by barying the angle between the two tabs of the 6-pole
magnets.
(g) Horizontal green and red lines are converged by varying the tabs together, keeping the angle
between them constant.