
2. HARDWARE
B–62835EN/01
136
The 7.2–inch monochrome LCD is provided with a contrast adjustment
potentiometer and video signal adjustment switches.
The contrast is adjusted when the LCD adapter or panel is replaced.
Otherwise, it should not be necessary to use the adjustment switches.
VRP1
SW1
VR1
7.2–inch monochrome LCD (rear view)
(1) Contrast adjustment
Potentiometer VRP1
This adjustment is made to compensate for variations between,
individual LCD adapters and LCD panels. When an LCD adapter or
panel is replaced, the following adjustment must be made. If the
entire LCD unit is replaced, however, no adjustment is needed.
(a) First, adjust potentiometer VRP1 until the displayed characters
(all black areas) appear white.
(b) Rotate the potentiometer in the opposite direction until the
characters appear clear and black.
(2) Flicker adjustment
Potentiometer VR1
This potentiometer is factory–set and normally need not be adjusted
by the user. If the setting is changed by mistake, re–adjust it
according to the following procedure. Note that some versions of this
printed–circuit board do not have this potentiometer; adjustment is
performed automatically.
(a) Using the check pins, observe HS and CLK on an oscilloscope.
(b) Over part of the range of potentiometer VR1, the positive–going
edge of HS will be almost in phase with the positive–going edge
of the CLK. Rotating the potentiometer a little does not change
the phase difference. Set the potentiometer to the midpoint of this
range.
(c) After completing the adjustment, confirm that the display does
not flicker.
2.12
7.2–INCH
MONOCHROME LCD
ADJUSTMENT
Adjustment points
Adjustment procedure