Garmin GNS 480 Installation Manual page 109

Message Audio Volume Level Adjustment
The message audio volume was preset at the factory to a typical audio level. The level can be adjusted as
follows:
1. Press the COM bezel key, followed by the MENU/ENTER key to display the com menu. Press the
AUDIO line select key to display the volume adjustment window. The audio message (AMA)
selection will be selected. Rotate the PWR/VOL knob or the small, inner knob to adjust the audio
message volume level. The audio message level is displayed as a horizontal bar, showing the level
from zero to 100%.
2. Press the MENU/ENTER key when done.
3.3.2.4.2 Baro Correction Potentiometer
The GNS 480 can receive baro correction from an external potentiometer. This check verifies that the
GNS 480 is receiving baro correction data from the altimeter. Ensure that the GNS 480 is turned on. If
the following steps do not perform correctly, check the electrical connections and configuration setup.
1. Check the baro correction using the Configuration page. This page is accessed by pressing the FN
key twice, causing the SYS smart key to be displayed. The SYS smart key is then pressed, followed
by the CNFG smart key, if necessary. The baro correction is the first item on the list (Baro
Correct.).
2. Verify that the baro correction decodes properly from 28.10 to 31.00 "Hg (952 to 1050 mB). The
value displayed on the GNS 480 should be within ± 0.03 "Hg (±1 mB) of the altimeter setting.
3.3.2.4.3 Air Data Computer, Altitude Encoder and Fuel Air/Data Computer
The GNS 480 can receive altitude or fuel/air data from an external source. This check verifies that the
GNS 480 is receiving data from these units. Ensure that the GNS 480 and MX20 are turned on and in
normal mode. If the following steps do not perform correctly, check the electrical connections and
configuration setup.
For dual GNS 480 installations, this check must be performed for each GNS 480. While
this check is carried out, the other GNS 480 must be turned off.
3. Press the MAP bezel key and use the large, outer knob to select MAP 2.
4. Press the MENU/ENTER key to display the line select key functions, and repeatedly press the
MORE line select key until the NAV DATA line select key legend is displayed.
5. Press the NAV DATA line select key to display nav data in the window on the left.
6. The ALT field will display the baro-corrected altitude. If the ALT field is not displayed, press the
SEL DATA line select key and use the small, inner knob to select the ALT field for display and
press MENU/ENTER when the appropriate field is selected. Verify that this altitude value is not
dashed out, and that the altitude agrees with the altimeter (±125 ft).
The baro-correction that is set on the altimeter and GNS 480 must be the same in order
for the displayed altitude values to agree.
7. If fuel data is being provided to the GNS 480, press the MENU/ENTER key to display the line select
key functions, and repeatedly press the MORE line select key until the NAV DATA line select key
legend is displayed.
GNS 480 (CNX80) Installation Manual560-0982-01 Rev A
Post-Installation Configuration & Checkout
NOTE
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