Lighting Configuration Page; Figure 6-9. Lighting Configuration Page; Figure 6-10. Photocell Configuration Page - Garmin GTN 635 Installation Manual

6.6.6

Lighting Configuration Page

Access the Lighting Configuration page, as shown in
Figure 6-9, by touching the ‗Lighting' key on the GTN
Setup page. This page allows you to set display
parameters that affect the display backlight and key
lighting brightness.
SOURCE
Selection
Photocell
Lighting Bus 1
Lighting Bus 2
Note that the display source can only be configured to track the photocell or lighting bus 1. If the aircraft
has a single lighting bus, display and key brightness can be set to track Lighting Bus 1.
MINIMUM LEVEL
This sets the minimum brightness of the keys or display, whichever is applicable. Touch the ‗Minimum
Level' key corresponding to either the Keys or the Display to adjust the minimum brightness. The
minimum brightness level for the display can be adjusted in a range from 0.14% to 100.00%, with
100.00% being the highest brightness level. The minimum brightness level for the keys can be adjusted in
a range from 0.00% to 100.00%, with 100.00% being the highest brightness level. The display and key
brightness default level is set to 5.00% at the factory. Enter the desired minimum value on the keypad and
then touch the ‗Enter' key to store the settings.
6.6.6.1 Configure Photocell Page
Access the Photocell Configuration page, as shown in
Figure 6-10 by touching the ‗Configure Photocell' key
from the Lighting Configuration page. The following
parameters can be configured by touching the
corresponding key. Each selection displays a numeric
keypad where the numeric values can be entered.
RESPONSE TIME
Sets the speed with which the brightness responds to the
input level (bus voltage or ambient light) changes. The
higher the number the slower the display responds. This
field has a range of 2-7 seconds, and is set to 2 seconds as a default value.
SLOPE
Sets the sensitivity the brightness of the display has to changes in the input level. The higher the number,
the brighter the display for a given increase in the input level. This field has a range of 0-100, and is set to
50 as the default setting.
OFFSET
Adjusts the lighting level up or down for any given input level. This field has a range of 0 (zero) to 99,
and is set to 50. At 50, there is no offset. This may also be used to match lighting curves with other
equipment in the panel.
GTN 625/635/650 TSO Installation Manual
190-01004-02
Backlight or key lighting level is determined by the ambient light level
as measured by the photocell on the GTN.
Backlight or key levels track the Lighting Bus 1 levels.
Key lighting levels track the Lighting Bus 2 levels.

Figure 6-9. Lighting Configuration Page

Description

Figure 6-10. Photocell Configuration Page

Page 6-11
Rev. C