Northern Airborne Technology AMS42 - Manual (Page 24)

SM19 Rev 4.00 AMS42/44 Dual Channel Audio Controller Manual
Page 2-6 Nov 21, 2003
ENG-FORM: 805-0102.DOT
CONFIDENTIAL AND PROPRIETARY TO NORTHERN AIRBORNE TECHNOLOGY LTD.
2.5.4 Post-Installation Checks
With the controller disconnected from its mating connector, check P101 pin <17> for
+28 Vdc relative to ground, and check P101 pin <34> for continuity to ground (below 0.5
Ω). Check P102 pin <19> for the presence of the lamp dimmer voltage. Check all mic,
phone, music, and key lines for shorts to ground or adjacent pins. Check all key lines
for correct operation. Do not attach the audio controller until these conditions are
met.
Power up the aircraft's system with the unit installed and turn on the radios and
accessories required for the system. Refer to Section 3.0 for operation and set-up
information.
Start with only the pilot's headset installed. Check for correct ICS, radio, and transmit
operation. Do not proceed until the radios are functioning correctly. The S/T (sidetone)
adjustment accessible through the right side of the controller and the transceiver
internal adjustment may have to be adjusted for correct balance for the pilot and copilot.
Adjustment of the individual radio RX levels should be set first, then the front panel RX
master volume control.
Unusual buzzes, hums or other background audio are symptomatic of multiple grounds
or noisy external systems sharing the same wire bundle. Note that incorrect jack wiring
is a common fault, especially for passenger stations, and may cause loss of audio, a
tone on the headset lines, or other problems. Failure to key or correctly modulate a
transceiver may be caused by missing grounds on the radio or audio controller.
Plug in the hand mic and test for correct operation. Note that wiring faults for this
accessory may cause peculiar loss of ICS or TX functions because it has over-riding
priority in the system.
Plug in the remaining headsets and check for proper operation.
Note: an incorrect drop cord or improper jack wiring may cause a wide range of
problems from loss of audio to a tone heard in the headset.
Check levels and operation of all functions in flight to ensure proper adjustments and
settings have been made.