Install Manual

Preliminary
SKY899
Installation Manual
F-5
Rev. A
NOTE
To prevent SKYWATCH HP from tracking the movement of the test-set, it is
necessary to set the TT391 POWER switch to OFF after completing each
bearing measurement.
23. Return the TT391 assemblies to their position in the aluminum carrying case.
24. Restart SKYWATCH HP by cycling power OFF and then ON.
25. Connect an oscilloscope to the suppression bus and verify that the SKY899 suppression pulse (100 µs
±5 µs) exceeds +15 V dc, if less than +15 V dc the suppression bus is overloaded. Check all equipment
connected to the bus. Repair/replace the offending device.
26. This completes the post installation checkout procedure.
F.4 SELF TEST
1. Turn SKYWATCH HP OFF and then:
a. Make sure the aircraft's transponder is in the STANDBY, ON, or ALT mode.
NOTE
After power up, it may take a couple of minutes for the altitude encoder to
return a valid altitude to the transponder and SKY899.
b. If installed, power up the radio altimeter.
c. Make sure all compass/HSI flags are cleared from the aircraft's instruments.
2. Turn SKYWATCH HP ON.
3. After approximately thirty seconds, observe the standby screen and then perform the SKYWATCH
HP self test (see alternate display operating instructions on how to perform self test).
4. If SKYWATCH HP passes the self-test, the system will return to the standby screen and the voice
message, "SKYWATCH SYSTEM TEST PASSED," will be enunciated over the cockpit audio system.
5. If you do not hear the voice message or if the voice message is of insufficient volume:
a. Check headphones/speaker and aircraft audio panel switch settings.
NOTE
Audio levels are adjusted via the service menu and at the aircraft audio
panel. There is no internal audio adjustment.
b. Reset the audio level via the service menu (see paragraph 4.4.1.3).
c. Check audio connection to the TRC:
1) 600-ohm audio systems should be connected to P1-89 (AUDIO_H).
2) 150-ohm audio systems should be connected to P1-90 (AUDIO_L).
3) Audio common is connected to P1-91 (AUDIO_C).
NOTE
Audio output from the TRC is transformer isolated.
6. If SKYWATCH HP fails the self-test:
a. The fail screen will be displayed.
b. The voice message, "SKYWATCH SYSTEM TEST FAILED", will be enunciated over the cockpit
audio system.
c. Refer to the fault isolation procedures and error messages in Chapter 4.