GTN 625/635/650 TSO Installation Manual 190-01004-02Page 6-64 Rev. F6.12.2.4 Sandel SN3500/4500 Interface CheckIf a Sandel SN3500/4500 EHSI has been connected to the GTN, the interface should be verified asdescribed in this section.1. Cycle power to the GTN and acknowledge the prompts until it gets to the Instrument Panel SelfTest page (see Section 6.11.1).2. Ensure that the SN3500/4500 is receiving valid heading.NOTEThe Vertical Deviation Indication will not be displayed unless the SN3500 is receivingvalid heading.3. While the GTN is displaying the self test page, verify that the SN3500/4500 is displaying datafrom the GPS source.Course Deviation: Half-scale left deviation, TO indication, flag pulledVertical Deviation:Half-scale up deviation, flag pulledActive Waypoint:GARMN4. On the GTN verify that an OBS value is displayed (and not dashed out).5. Acknowledge the self test on the GTN by touching the ‘Continue’ key.6. Select VLOC on the GTN and verify that the SN3308 displays NAV 1 or NAV 2 (depending on what navigation source the GTN is).7. Ensure that the NAV1 (or NAV2) indication does not have a red line through it.6.12.3 EHSI Deviation Scaling (If HSI/CDI Is Driven by the GTN Via Serial Data)If the GTN has a serial connection to an EFIS display, proper scaling of the EFIS CDI and VDI must beverified.1. Cycle power to the GTN and acknowledge the prompts until it gets to the Instrument Panel SelfTest page (see Section 6.11.1).2. With the Instrument Panel Self Test displayed on the GTN, look at the EHSI/EFIS and verify thatthe lateral deviation is not flagged and half-scale left.3. With the Instrument Panel Self Test displayed on the GTN, look at the EHSI/EFIS and verify thatthe vertical deviation is not flagged and half-scale up.NOTEIf the deviations are not as described, the EHSI/EFIS does not scale the GTN deviationsproperly and cannot be certified for GPS-based guidance. Contact Garmin for furtherassistance.
