Garmin AT Rev --8-20 GX Service Manual © 2004 Garmin ATNAV Board ReplacementThis procedure describes the removal and replacement of the NAV board.Parts Required• 221-0401 SCREW, PAN HEAD PHILIPS, 4-40 X ¼" W/SPLIT LOCK WASHER, STAINLESSSTEEL (8 required for GX55, 4 required for GX50/60/65)• 224-0403 SCREW, UNDERCUT, PAN HEAD PHILIPS, 4-40 X 3/16", 82 DEGREE, STAINLESSSTEEL (4 required for GX55, 3 required for GX50/60/65)• 415-7004-00 NAVIGATION COMPUTER BOARD, GX50/60/65• 415-7004-20 NAVIGATION COMPUTER BOARD, GX55Removal1. Before starting this procedure, fill out a Service Data Sheet if this has not already been done. Acopy is located at the back of this manual.2. Power the unit off and disconnect power from the unit.3. Remove the bezel assembly (see Bezel Assembly Replacement procedure).4. On the GX60/ 65, remove the Comm board first (see Comm Board Replacement procedure).5. Remove the GPS board (see GX50/55 or GX60/65 GPS Board Replacement procedure).6. Remove the screws (four on the GX55, three on the GX50/60/65) holding down the NAV board.7. Remove the outer screw from the right side of the chassis.8. Remove the screws (four on the GX55, two on the GX50/60/65) that hold the D-sub connector onthe back of the chassis.9. On the GX55, remove the filler plate by sliding it up out of the rear of the chassis.10. Lift the NAV board from the chassis.Replacement1. Put the new NAV board (see the Parts Required section above for the correct part number) inplace in the chassis on the right side.2. On the GX55, replace the filler plate on the back of the chassis.3. Replace the screws (221-0401) (four on the GX55, two on the GX50/60/65) that hold the D-subconnector on the back of the chassis. Torque the screws to 5.0 lb.-in.4. Replace the screw (224-0403) on the outside that holds the NAV board. Torque the screw to 5.0lb.-in.5. Replace the screws (221-0401) (four GX55, three on the GX50/60/65) that hold down the NAVboard. Torque the screws to 5.0 lb.-in.6. Replace the GPS board (see GX50/55 or GX60/65 GPS Board Replacement procedure).7. On the GX60/ 65, replace the Comm board (see Comm Board Replacement procedure).8. Replace the bezel assembly (see Bezel Assembly Replacement procedure).9. Completely reinitialize the unit (see Complete Initialization procedure).10. Test the unit to verify proper operation (see Return to Service procedures).11. Using the Service Data Sheet, reenter the customer configuration.