Service manual

2. TROUBLESHOOTING
Service Manual CNS-9701 2.15
*
1
The VL-971R display unit is adjusted at the factory so that the display unit accepts the RGB signals from most of
the RADEON graphic boards used in the main unit. But some of the boards require adjustment of the display unit.
*
2
Most of these problems can be caused by a failure of the LCD control board in the display unit because the RGB
outputs from the graphic board are controlled by an IC on the graphic board.
*
3
To judge which board has a failure, connect another PC to the display unit or another RGB display unit to the
main unit.
Problem Possible Cause Action
A failure of the display unit*
2
or
graphic board of the main unit.
Replace the defective board*
3
with a new
one.
Internal break in the RGB cable Check the continuity with a multimeter.
Replace the cable with a new one if the
cable has a break.
- The display color balance
has something wrong.
- The screen background
color is not black.
Adjustment*
1
of the display unit is
required.
Adjust the display unit according to
"Adjustment" section.
Failure of the AC adapter in the
display unit.
Check that the AC adapter outputs +12 V.
If this voltage is not output, replace the AC
adapter with a new one.
No screen is displayed but the
backlight lamp is not lit.
Failure of the backlight lamp or
inverter of the LCD assembly.
Replace the LCD assembly with a new
one.
If NDS logo appears at the center
of the screen when you turn on the
display unit only, the display unit
works.
Check that the RGB signals are output
from the main unit. Adjust the display unit
synchronization according to the
"Adjustment" section.
No screen is displayed but the
backlight lamp is lit.
If NDS logo does not appear at the
center of the screen when you turn
on the display unit only, the
display unit does not work.
Replace the LCD control board or LCD
assembly with a new one.