Garmin APOLLO GX SERIES Service Manual

Contents

Garmin AT Rev --© 2004 Garmin AT GX Service Manual 9-3SymptomsSYMPTOM CAUSE ACTIONHold or flip/flop inputfailure1. External switch2. Nav board1. Check continuity of external switch.2. Replace the NAV board. (See NAVBoard Replacement procedure.)Squelch open or closefailureFactory alignment not tocurrent specificationReplace Comm board. (See CommBoard Replacement procedure.)Can’t access data cardData card failed1. Data card2. NAV board1. Reinsert data card (make sure it isright side up).2. Try another data card.3. Replace the NAV board. (See NAVBoard Replacement procedure.)Loss of communicationwith peripheral device1. Serial portconfiguration2. Serial portcommunication3. NAV board1. In the Test mode, check that theserial port setup is correct.2. Check the Serial port. (See SerialPorts on page 7-13).3. Replace the NAV board. (See NAVBoard Replacement procedure.)Comm is interfering w/GPS(Some of the action stepsare assuming that thereare separate GPS andRadio units.)1. Harmonics fromComm2. Proximity of antennas3. Aircraft componentinterference1. Install notch filter part # 162-1059on GPS antenna coax connector onthe back of the chassis.2. Try new RG-142 instead of RG-58coax for Comm and GPS antennas.3. Ground Nav/Comm and GPS rackstogether and to A/C ground.4. Rearrange the stack to getmaximum distance between theGPS and Nav/Comm.5. Separate the GPS and Nav/Commwiring at the back of the rack. Wrapshielding around each bundle ofwires, then ground these to A/Cground.6. Minimize any extra wire lengths.7. Try grounding wire shields at bothends of the wire.8. Separate Comm and GPSantennas.9. Isolate to interfering component.10. Move GPS antenna from line ofsight with interfering equipment.Comm not changingfrequencies1. Channels locked2. Comm board1. Replace Comm board. (See CommBoard Replacement procedure.)