Northern Airborne Technology 251 - Manual (Page 10)

Model 251 Passenger Speaker Amplifier
SM251 Installation and Operation Manual
Section 2 Rev: 1.00 Issue 2 Page 2-2
ENG-FORM: 805-0120.DOT
CONFIDENTIAL AND PROPRIETARY TO NORTHERN AIRBORNE TECHNOLOGY LTD.
2.4.1 Warnings
WARNING:
High volume settings can cause hearing damage.
Set the headset volume control to the minimum setting prior to
conducting tests, and slowly increase the headset volume to a
comfortable listening level.
2.4.2 Cautions
CAUTION:
Do not bundle any lines from this unit with transmitter coax feed lines. Do not
bundle any audio or DC power lines from this unit with 400 Hz synchro wiring
or AC power lines. Do not position this unit next to any device with a strong
alternating magnetic field such as an inverter, motor or blower, or significant
audio interference will result.
In all installations, use shielded cable exactly as shown, and ground only as
indicated. Significant problems may result from not following these guidelines.
Failure to follow the installation and wiring instructions provided in this manual
for power and ground connections, including the rating of the circuit breaker,
may lead to damage in the power input circuitry of the unit.
2.4.3 Cabling and Wiring
All wire shall be selected in accordance with the original aircraft manufacturer's Maintenance Instructions
or AC43.13-1B Change 1, Paragraphs 11-76 through 11-78. Unshielded wire types shall qualify to
MIL-W-22759 as specified in AC43.13-1B Change 1, Paragraphs 11-85, 11-86, and listed in Table 11-11.
For shielded wire applications, use Tefzel MIL-C-27500 shielded wire with solder sleeves (for shield
terminations) to make the most compact and easily terminated interconnect. Follow the Wiring Diagram in
Section 2.4.7 as required.
Allow 3" from the end of the shielded wiring to the shield termination to allow the connector hood to be
easily installed. Refer to the Wiring Diagram in Section 2.4.7 for shield termination details. Note that the
hood is a "clamshell" hood, and is installed after the wiring is complete.
Maintain wire segregation and route wiring in accordance with the original aircraft manufacturers
Maintenance Instructions.
Unless otherwise noted, power, ground and speaker wiring shall be a minimum of 20 AWG, and all others
shall be a minimum of 22 AWG. Refer to the Wiring Diagram for additional specifications. Check that the
ground connection is clean and well secured, and that it shares no path with any electrically noisy aircraft
accessories such as blowers, turn and bank instruments or similar loads. Power to this unit must be
supplied from a separate circuit breaker or fuse (fast blow), and not attached to any other circuit breaker
without additional protection. Verify that the selected circuit breaker size and wire gauge are adequate for
the installation using the techniques specified in AC43.13-1B Change 1, Paragraphs 11-47 through 11-51
and 11-66 through 11-69.