Mid-Continent Instruments and Avionics, Wichita, KS
REV. B, October 31, 2012
37
Manual Number 9017782
4.3.1
DIMMING CONTROL
The DIMMING CONTROL setting allows the installer to select the source of dimming
control. It can be an external source, typically the aircraft’s adjustable lighting bus, or it
can use the INTERNAL photocell built into the unit which senses the ambient light
conditions and adjusts the display brightness/dimming automatically. If an external
source is to be used, the EXT 5V, EXT 14V, and EXT 28V options represent the input
voltage range the unit will accept (0-5VDC, 0-14VDC, and 0-28VDC, respectively).
This feature is provided for maximum installation flexibility and control for the pilot.
See Figure 4.8.
FIGURE 4.8
4.3.2
DIMMING CURVE
The DIMMING CURVE feature allows the installer to customize the response to the
DIMMING CONTROL input, whether internal or external, over its range of operation.
Therefore, for various points throughout the input range, the brightness can be adjusted
up or down to produce a unique dimming scheme that most closely matches the other
instruments in the panel and the pilot’s preferences. This feature is provided for
maximum installation flexibility and control for the pilot.
NOTE: When new, the display is daylight-visible at approximately 75% brightness. It may
not be necessary to set the dimming curve to 100%. Setting the high-brightness side of
the dimming curve to less than 100% will extend the life of the LED backlight and
provide margin for the pilot to increase brightness as desired.
When setting the dimming curve with the dimming control set to INTERNAL, the X-axis
of the dimming graph will read AMBIENT and will range from MIN to MAX. This
represents the brightness of the light the unit’s photocell can see and shows the current
ambient light level with the vertical blue line. The Y-axis represents brightness of the
display. It will track the dimming curve with the horizontal blue line as the input light
increases or decreases. The best method for setting the dimming curve is to simulate the
range of lighting conditions. This is best done after installation, in the actual aircraft
instrument panel, but can be simulated in various environments. See Figure 4.9.
1)
Change the light of the cockpit or general area around the unit until the vertical
blue line matches (or nearly matches) the yellow highlighted point on the graph.
2)
Adjust the control knob to increase or decrease the brightness of the display
to the desired level at that lighting condition (the point will move up or
down, respectively).
3)
When satisfied, press the control knob.
4)
The next point will be highlighted.
5)
Repeat Steps 1-4 for each point on the graph.
