Garmin GTN 725 Maintenance Manual
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Garmin GTN 725 Maintenance Manual

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GTN 725/750
Maintenance Manual
190-01007-01
March 2019
Revision 5

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Summary of Contents for Garmin GTN 725

  • Page 1 GTN 725/750 Maintenance Manual 190-01007-01 March 2019 Revision 5...
  • Page 2 Garmin. Garmin hereby grants permission to download a single copy of this manual and of any revision to this manual onto a hard drive or other electronic storage medium to be viewed and to...
  • Page 3 Added instructions for installation and removal of HW Mod 7, Battery 12/03/2018 Accessory. 03/11/19 Updated internal datacard part number. CURRENT REVISION DESCRIPTION Section Page Description of Change Number(s) Number(s) 5-10 Updated datacard part number in step 1 of replacement instructions. 190-01007-01 GTN 725/750 Maintenance Manual Rev. 5 Page ii...
  • Page 4 United States without first obtaining an export license. The information in this document is subject to change without notice. For updates and supplemental information regarding the operation of Garmin products visit flyGarmin.com.
  • Page 5 Refer to www.dtsc.ca.gov/hazardouswaste/perchlorate. CAUTION The GTN 725/750 has a display coated with a special anti-reflective coating which is very sensitive to waxes and abrasive cleaners. CLEANERS CONTAINING AMMONIA WILL HARM THE ANTI-REFLECTIVE COATING. It is very important to clean the display using a clean, lint-free cloth and an eyeglass lens cleaner which is safe for anti-reflective coatings.
  • Page 6 All information depicted in screen shots, including software file names, versions, and part numbers, is subject to change and may not be up to date. 190-01007-01 GTN 725/750 Maintenance Manual Rev. 5 Page v...
  • Page 7 GTN 725/750 SERVICE BULLETIN HISTORY The following table identifies service bulletins for the GTN 725/750. The table is current at the time of publication of this manual (refer to date on front cover) and is subject to change without notice. Authorized...
  • Page 8 Service Bulletin Service Bulletin Purpose of Bulletin Number Date GTN 625/635/650 and GTN 725/750 TSO Install 1339 06/19/2013 Manual Changes - Remove AFMS Section TSO Authorization GTN Software Upgrade to Software 1321 04/30/2013 V4.10, COM Software V2.11, and GMA 35 V3.05 GTN 6XX/7XX Software Main 2.00, COM 2.00 or...

  • Page 9: Table Of Contents

    .................. 5-1 EMOVAL AND EPLACEMENT ROCEDURES 5.1 GTN 725/750 Unit Removal and Replacement ................5-2 5.2 GTN Removal with Damaged Jackscrew ..................5-3 5.3 Fan Removal and Replacement......................5-4 5.4 I/O Chassis Removal and Replacement .................... 5-5 5.5 Memory Battery Removal and Replacement ..................5-6 5.6 Bottom Cover Removal and Replacement..................
  • Page 10 Figure 4-1 LRU Failure Annunciations ....................4-1 Figure 4-2 GTN 725/750 Message Flag ....................4-3 Figure 4-3 GTN 725/750 Message Page ....................4-3 Figure 5-1 GTN 725/750 Unit Retention Mechanism Adjustment ............5-2 Figure 5-2 Cam Head Removal .......................5-3 Figure 5-3 Fan/Backplate Orientation .....................5-4 Figure 5-4 I/O Chassis Removal ......................5-5...
  • Page 11 Table 4-7 TAWS Messages ........................4-8 Table 4-8 Database Messages ........................4-9 Table 4-9 Operational Checks ......................4-10 Table 4-10 Mechanical Failures ......................4-11 Table 5-1 Hardware Torque Values .......................5-1 Table 7-1 Service Parts ...........................7-1 190-01007-01 GTN 725/750 Maintenance Manual Rev. 5 Page ix...

  • Page 12: General Information

    Olathe, KS 66062 1.3 Related Publications The information contained in this manual can be used in conjunction with information from the Garmin publications listed in this manual, as well as related third party device documentation. The Garmin publications listed below are available for download from the Garmin Dealer Resource Center.

  • Page 13: Gtn 725/750 Overview

    GTX 32/33 remote transponder, and the GDL 88 remote ADS-B transceiver. GTN 750 In addition to all of the features of the GTN 725, the GTN 750 includes an airborne VHF communications transceiver and airborne VOR/localizer (LOC) and glideslope (G/S) receivers.

  • Page 14: Unit Interfaces

    The GTN 725/750 interfaces with other avionics units through the rear connectors shown in figure 2-2. Figure 2-3 shows a summary of GTN 725/750 external signal and power interfaces. Note that COM and NAV boards are present only in the GTN 750.

  • Page 15: Figure 2-3 Gtn 725/750 Block Diagram

    J1005 RS-232 IN/OUT (GTN 750 ONLY) ARINC 429 IN/OUT SYNCRO GPS/SBAS ANTENNA J1006 COM ANTENNA J1007 (GTN 750 ONLY) NAV ANTENNA J1008 (GTN 750 ONLY) Figure 2-3 GTN 725/750 Block Diagram 190-01007-01 GTN 725/750 Maintenance Manual Rev. 5 Page 2-3...

  • Page 16: Control And Operation Information

    Battery replacement and removal must be performed by an Garmin Authorized Repair Station. The GTN 725/750 includes an internal lithium battery and will last 5 to 8 years. The battery is used for internal time clock and GPS system information. Regular, planned replacement is not necessary. The GTN 725/750 will display “Low Battery”...

  • Page 17: Theory Of Operation

    3 THEORY OF OPERATION 3.1 Front Panel Assembly The front panel assembly of the GTN 725/750 consists of the front panel and the touchscreen. The GTN 725/750 navigators feature a 6.9" diagonal touchscreen which is used to perform most functions. The front panel contains a data card slot, photocell, supplemental hard keys, volume control knob, and dual concentric control knobs.

  • Page 18: Troubleshooting

    System messages Follow the assembly/disassembly procedures in section 5 to remove the GTN unit or component. Follow instructions in section 1.2 to return the unit or component to Garmin for repair. If the following troubleshooting approaches are unsuccessful, visit flyGarmin.com.

  • Page 19: Table 4-1 Com Lru Failure Annunciation Troubleshooting Guide

    Perform a NAV harness NAV harness power/ Replace the GTN. power/ground test. ground circuit Refer to section 5.1 for Refer to appendix A.4 functioning normally. details. for pinout information. 190-01007-01 GTN 725/750 Maintenance Manual Rev. 5 Page 4-2...

  • Page 20: System Messages

    4.2 System Messages GTN 725/750 System messages are accessed by touching the MSG key on the Home page, shown in figure 4-2. System messages are also displayed on the Message page, shown in figure 4-3. Figure 4-2 GTN 725/750 Message Flag...

  • Page 21: Table 4-3 Gtn 7Xx System Messages

    • Check that the cooling fan is unobstructed. Reducing backlight The backlight has been • Check fan wiring. Refer to GTN 725/750 TSO brightness. automatically dimmed to Installation Manual, P/N 190-01007-02 for reduce the unit temperature. details.
  • Page 22 • If the message persists, replace the GTN. Volume knob is stuck in the pressed state. Refer to section 5.1 for details. stuck in the Knob is located on the upper pressed position. left corner of the bezel. 190-01007-01 GTN 725/750 Maintenance Manual Rev. 5 Page 4-5...

  • Page 23: Table 4-4 Gps/Sbas Messages

    • Check GPS antenna and cable connections. LOSS OF • Make sure the aircraft is clear of hangars, INTEGRITY (LOI) - buildings, trees, etc. Verify GPS position Antenna shaded from with other satellites. navigation equipment. 190-01007-01 GTN 725/750 Maintenance Manual Rev. 5 Page 4-6...

  • Page 24: Table 4-5 Vloc/Glideslope Messages (Gtn 750 Only)

    The GTN 750 has detected has failed. details. an internal failure in its VLOC receiver. VLOC RECEIVER - Navigation receiver Replace the GTN. Refer to section 5.1 for details. needs service. 190-01007-01 GTN 725/750 Maintenance Manual Rev. 5 Page 4-7...

  • Page 25: Table 4-6 Com Messages (Gtn 750 Only)

    Reselect the TAWS or terrain - Terrain/TAWS The TAWS configuration is selection and cycle power to the GTN. configuration is invalid due to a loss or • If the problem persists, contact Garmin invalid. GTN needs corrupt registry. Technical support. service. 190-01007-01 GTN 725/750 Maintenance Manual Rev.

  • Page 26: Table 4-8 Database Messages

    External SD card has an error and the unit is not able DATACARD to read the databases. Replace the SD card. Contact Garmin technical ERROR - SD card ChartView, FlightCharts, and support. is invalid or failed. Terrain databases will not be accessible by the unit.

  • Page 27: Table 4-9 Operational Checks

    OBS indication on • If the problem persists, replace the GTN. GTN does not GTN resolver or resolver Refer to section 5.1 for details. agree with OBS input not calibrated. setting. 190-01007-01 GTN 725/750 Maintenance Manual Rev. 5 Page 4-10...

  • Page 28: Table 4-10 Mechanical Failures

    • Remove and replace the GTN bottom cover. freely for more than Install arm jackscrew head is Refer to section 5.6 for details. 18 revolutions stripped. when tightening or loosening. 190-01007-01 GTN 725/750 Maintenance Manual Rev. 5 Page 4-11...

  • Page 29: Removal And Replacement Procedures

    CAUTION Removal or replacement of components not addressed in this section by any person other than a Garmin authorized repair station representative may void the product warranty. For complete information regarding Garmin aviation warranty policies and procedures, refer to Garmin Aviation Warranty Policies and Procedures, P/N M02-60069-00.

  • Page 30: Gtn 725/750 Unit Removal And Replacement

    UNIT RETENTION MECHANISM ACCESS HOLE Figure 5-1 GTN 725/750 Unit Retention Mechanism Adjustment 190-01007-01 GTN 725/750 Maintenance Manual Rev. 5...

  • Page 31: Gtn Removal With Damaged Jackscrew

    Instead replace the entire bottom cover. 5. Remove the GTN from the rack. 6. Remove and replace the bottom cover. Refer to section 5.6 for details. Figure 5-2 Cam Head Removal 190-01007-01 GTN 725/750 Maintenance Manual Rev. 5 Page 5-3...

  • Page 32: Fan Removal And Replacement

    The GTN cooling fan assembly is located behind the rack relative to the unit. Fan removal and replacement details for specific installations fall outside the scope of this manual. Refer to the applicable figure in Appendix C of GTN 725/750 TSO Installation Manual (P/N 190-01007-02) while performing the following procedure.

  • Page 33: I/O Chassis Removal And Replacement

    4-40 x 0.375" panhead screw on the left side. 3. Attach the head/chassis top brace to the display head with a 4-40 x 0.25" panhead screw. 4-40x0.375" Screw Figure 5-4 I/O Chassis Removal 190-01007-01 GTN 725/750 Maintenance Manual Rev. 5 Page 5-5...

  • Page 34: Memory Battery Removal And Replacement

    3. Replace the battery cover clip on the battery holder. Clip orientation is not important. 4. Ensure the battery cover clip is fully seated and engaged on both ends. Figure 5-5 Memory Battery Location and Orientation 190-01007-01 GTN 725/750 Maintenance Manual Rev. 5 Page 5-6...

  • Page 35: Figure 5-6 Battery Assembly Contacts

    1. Apply a thin layer of dielectric grease to the replacement battery contacts. 2. Place low-capacity battery assembly into the holder. 3. Ensure battery assembly clips are fully seated and engaged on both ends. Figure 5-6 Battery Assembly Contacts 190-01007-01 GTN 725/750 Maintenance Manual Rev. 5 Page 5-7...

  • Page 36: Bottom Cover Removal And Replacement

    1. Place the bottom cover on the COM/NAV chassis. 2. Replace the single 4-40 x 0.25” countersunk screw first to ensure proper cover alignment. 3. Replace the four 4-40 x 0.25” panhead screws. Figure 5-7 Bottom Cover 190-01007-01 GTN 725/750 Maintenance Manual Rev. 5 Page 5-8...

  • Page 37: Knob Removal And Replacement

    5. Replace the inner dual knob. Refer to section 5.7.2. COM Volume Knob (430-00053-00) Outer Dual Knob (430-00055-00) Inner Dual Knob (430-00054-00) Figure 5-8 GTN 725/750 Unit Knobs 190-01007-01 GTN 725/750 Maintenance Manual Rev. 5 Page 5-9...

  • Page 38: Internal Datacard Removal And Replacement

    1. Insert the new datacard (P/N 011-02512-01) into the datacard slot, press until seated. 2. Apply a new aluminum foil label (P/N 249-00211-02) to cover the datacard slot. Aluminum Foil Label Covering ard Slot Figure 5-9 Internal Datacard Access Slot 190-01007-01 GTN 725/750 Maintenance Manual Rev. 5 Page 5-10...

  • Page 39: Return To Service

    6 RETURN TO SERVICE After removing and reinstalling the GTN 725/750 (according to the instructions in section 5.1) power up the GTN in normal mode. Check all software against current versions. Verify there are no GTN red Xs and no GTN-related alerts are present. If GTN red Xs or alerts are present, troubleshoot using section 4.

  • Page 40: Service Parts List

    GTN 6XX/7XX Bottom Cover Subassembly S11-02308-00 GTN Replacement Knob Set K00-00578-00 GTN Internal Datacard Replacement Kit, 8 GB K00-00927-00 GTN 6XX/7XX Low-capacity Battery Replacement Kit, 3.6v K00-01139-01 GTN Battery Replacement Kit K00-00696-00 190-01007-01 GTN 725/750 Maintenance Manual Rev. 5 Page 7-1...

  • Page 41: Appendixa Connector Pinout Information

    APPENDIX A CONNECTOR PINOUT INFORMATION This appendix contains connector diagrams and pinout tables for each connector on the GTN 725/750. The connector diagrams show pin orientation for the GTN (J) connectors. Connections are shown in figure A-1. J1005 J1001 J1006 GPS...

  • Page 42: J1001 Main Connector - Main Board

    RS-232 IN 1 ARINC 429 OUT 2B ARINC 429 OUT 1B MAIN +FROM OUT MAIN VERTICAL +DOWN OUT MAIN VERTICAL SUPERFLAG OUT WAYPOINT ANNUNCIATE* [1] TERMINAL ANNUNCIATE* [1] TAWS AUDIO ACTIVE OUT* [1] 190-01007-01 GTN 725/750 Maintenance Manual Rev. 5 Page A-2...
  • Page 43 MAIN LATERAL +RIGHT OUT MAIN LATERAL -FLAG OUT MAIN VERTICAL -FLAG OUT TERRAIN WARNING ANNUNCIATE* [1] TERRAIN NOT AVAILABLE ANNUNCIATE*[1] TERRAIN CAUTION ANNUNCIATE*[1] GPS SELECT*[1] TRAFFIC TEST*[1] TRAFFIC STANDBY*[1] AIRCRAFT GND 190-01007-01 GTN 725/750 Maintenance Manual Rev. 5 Page A-3...
  • Page 44 An asterisk (*) following a signal name denotes the signal is an Active-Low, requiring a ground to activate. If there is no asterisk, the signal is an Active-High. [1] This discrete may be configured to perform another function. Refer to GTN 725/750 TSO Installation Manual, P/N 190-01007-02 for more details. 190-01007-01 GTN 725/750 Maintenance Manual Rev.

  • Page 45: J1002 Connector

    If there is no asterisk, the signal is an Active-High. [1] This discrete may be configured to perform another function. Refer to GTN 725/750 TSO Installation Manual, P/N 190-01007-02 for more details. [2] In software version 5.00 or later, the SYSTEM ID PROGRAM* pin is no longer used.

  • Page 46: J1003 Com Connector (Gtn 750 Only

    500Ω COM AUDIO LO RESERVED MIC AUDIO IN LO RESERVED RESERVED RESERVED RESERVED RESERVED RESERVED COM REMOTE TRANSFER* COM REMOTE TUNE UP* COM REMOTE TUNE DOWN* AIRCRAFT POWER RESERVED RESERVED RESERVED RESERVED 190-01007-01 GTN 725/750 Maintenance Manual Rev. 5 Page A-6...
  • Page 47 AIRCRAFT POWER AIRCRAFT POWER An asterisk (*) following a signal name denotes the signal is an Active-Low, requiring a ground to activate. If there is no asterisk, the signal is an Active-High. 190-01007-01 GTN 725/750 Maintenance Manual Rev. 5 Page A-7...

  • Page 48: J1004 Nav Connector (Gtn 750 Only

    VOR/ILS ARINC 429 OUT B VOR/ILS ARINC 429 OUT A VOR OBI CLOCK VOR OBI SYNC VOR OBI DATA VLOC REMOTE TRANSFER ILS ENERGIZE RESERVED RESERVED GLIDESLOPE +FLAG PAR DME 1MHZ-D/SERIAL DME ON GLIDESLOPE +UP 190-01007-01 GTN 725/750 Maintenance Manual Rev. 5 Page A-8...
  • Page 49 AIRCRAFT GND AIRCRAFT GND An asterisk (*) following a signal name denotes the signal is an Active-Low, requiring a ground to activate. If there is no asterisk, the signal is an Active-High. 190-01007-01 GTN 725/750 Maintenance Manual Rev. 5 Page A-9...

  • Page 50: J1005 I/O Connector

    RS-232 OUT 6 RESERVED RESERVED RESERVED WX RADAR ON* SYNCHRO Y SYNCHRO REF LO ARINC 429 IN 3B ARINC 429 IN 4B RESERVED RESERVED RESERVED RESERVED RESERVED RESERVED RESERVED RESERVED RESERVED 190-01007-01 GTN 725/750 Maintenance Manual Rev. 5 Page A-10...
  • Page 51 RESERVED RESERVED RESERVED RESERVED RESERVED RS-232 GND 5 RS-232 GND 6 RESERVED RESERVED SPARE INPUT 1 SYNCHRO VALID INPUT (ACTIVE HI) RESERVED SYNCHRO Z RESERVED RESERVED RESERVED ARINC 453/708 IN 1B 190-01007-01 GTN 725/750 Maintenance Manual Rev. 5 Page A-11...
  • Page 52 Pin Name RESERVED ARINC 453/708 IN 2B 190-01007-01 GTN 725/750 Maintenance Manual Rev. 5 Page A-12...

  • Page 53: Appendixb Afm/Afms/Poh Considerations

    APPENDIX B AFM/AFMS/POH CONSIDERATIONS Refer to GTN 725/750 TSO Installation Manual, P/N 190-01007-02 for information on AFM/AFMS/POH considerations. 190-01007-01 GTN 725/750 Maintenance Manual Rev. 5 Page B-1...

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