System Maintenance Manual GTN 6XX/7XX Part 23 AML STC 190-01007-A1Page 7-4 Rev. 57.1.1 GTN Configuration Steps7.1.1.1 COM Configuration Page (GTN 635/650/750 Only)Select the COM Configuration page from the GTN Setup page. These values are set at the factory andrarely require calibration.To enable or disable the COM radio, touch the COM key to toggle between enabled and disabled. TheCOM radio defaults to the enabled state.Review the COM configuration settings on the GTN and compare them against the GTN Configurationand Checkout Log. A copy of the GTN Configuration and Checkout Log form may be found in theappendices of this document. If any of the settings differ from the checkout log, update the settings to thecorrect value. For information regarding individual settings, refer to the GTN 6XX/7XX AML STCInstallation Manual.7.1.1.2 Enabled FeaturesRefer to Section 7.5 for instructions on feature enablement. If the configuration module is not replaced, theenabled features will be retained upon replacing the GTN.7.1.2 GTN Ground ChecksGround checks of the GTN require the GTN to be powered up in configuration mode as described inSection 3.4.7.1.2.1 Connector Engagement CheckPrior to configuration and checkout of the GTN, the connector engagement should be checked as describedbelow:1. Ensure that the GTN GPS/NAV and COM circuit breakers are pulled.2. Slide the GTN straight into the rack until it stops about 1 inch short of the fully seated position.3. Insert a 3/32-inch hex drive into the unit retention mechanism access hole at the bottom of the unitface and rotate the tool clockwise while pressing the bezel until the unit is firmly seated in therack.4. With the GTN seated, reapply power by closing the circuit breakers and turning on the avionicsmaster switch (if installed).5. Again, insert the hex drive into the unit retention mechanism access hole. Rotate the tool counter-clockwise to back out the retention mechanism. Ensure that three (3) complete revolutions of theAllen screw can be performed without red ‘X’ indication or loss of power to the GTN.NOTEIf power is lost or the red ‘X’ condition occurs with fewer than three (3) turns, ensure thereare no obstructions to the unit fully seating in the rack. Also, the mounting rack may needto be moved aft (toward the pilot) such that the aircraft panel does not obstruct the unitfrom properly engaging in the rack.6. Pull the circuit breakers to remove power from the unit and re-seat the GTN per step 3. Close thebreakers to restore power to the unit.
