Service manual

3. DIAGNOSTIC CHECK
3.20 Service Manual BSM-4100
Backlight Check
This item checks the brightness control of the LCD backlight. While the
brightness is manually changed, check that it changes smoothly with no twinkling.
Check that the backlight goes off and has no twinkling when the brightness is set
to minimum.
If the brightness does not change smoothly or the light goes off in the middle of
the brightness bar on the screen, it indicates the end of life of the backlight or
faulty inverter board.
In that case, replace the inverter board, or fluorescent tube which is located on the
top of the backlight unit.
Procedure to Check the Brightness of the LCD Backlight
1. To select the Backlight Check, touch the “BACK LIGHT CHECK” key.
To control the brightness, touch the bargraph or the “↑” or “↓” key to increase
or decrease the brightness.
2. To return to the MANUAL CHECK MENU screen at any time, touch the
“RETURN” key.