Appendix B
Installation, Removal and Maintenance of the GNC 250
The aviation rack is designed to allow easy removal of the GNC 250. 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 250 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 250 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 250 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 250 can be removed from the rack.
83
The GNC 250 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 250 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 250 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.
SECTION
B
INSTALLATION &
MAINTENANCE
3/32” ALLEN
WRENCH
250 real 7/14/98 9:33 AM Page 83
