APPENDIX
B
INSTALLATION &
MAINTENANCE
Appendix B
Installation, Removal and Maintenance of the GNC 250XL
The aviation rack is designed to allow easy removal of the GNC 250XL. This enables you to
use the unit at home to create routes, interface to a PC, etc. using an optional AC adapter.
To install the GNC 250XL into the aviation rack:
1. Insert a 3/32” allen wrench in the small hole adjacent to the dual knob.
2. Rotate the wrench counterclockwise until it stops to ensure the pawl latch is in the
proper position.
3. Insert the GNC 250XL into the aviation rack and rotate the wrench clockwise to secure the unit. To ensure
proper connector seating, gently press on the left side of the unit until tightened.
To remove the GNC 250XL from the aviation rack:
1. Insert a 3/32” allen wrench in the small hole adjacent to the dual knob.
2. Rotate the wrench counterclockwise until the GNC 250XL can be removed from the rack.
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The GNC 250XL is built to exacting standards and
does not require user maintenance. If the faceplate and
lens require cleaning, use a soft cloth and non-abrasive
cleaner.
The user data is maintained by an internal battery with
a projected life of 3 to 5 years. If the GNC 250XL
detects a low memory battery, you will be informed
with the message ‘Memory battery low’. Failure to
have the battery replaced may result in loss of data
each time you turn your unit off. This will
greatly
increase satellite acquisition time and no user data will
be saved. This condition will be accompanied by the
message ‘Stored data lost’.
The GNC 250XL contains a crystal oscillator which
may drift after many years of operation. If the unit
detects excessive oscillator drift, you will be informed
with the message ‘Osc needs adjustment’. When this
occurs, contact an authorized GARMIN service center
for service. Failure to do so may result in severely
degraded acquisition performance.
3/32” ALLEN
WRENCH
250xl manual 2 7/17/98 1:33 PM Page 89