INSTALLATION

Helicopter (U174) connection diagram

WHT/BLU

6 MIC LO

 

WHT

5

MIC HI

 

BLU

 

4

COMM R

 

WHT

 

3

COMM L

 

BLK

 

2

GND

10-32 RED

1

V+IN

V DC

1/2A

 

 

Existing single 4-

 

prong jack

 

Existing wiring to

 

 

Barrel

helicopter intercom/

 

 

 

 

(audio gnd)

audio panel

 

 

 

 

 

Note: Barrel ground (gnd) refers to aircraft grounds.

Details on making the connections

The pinouts for the optional installed connector are detailed in the table below:

Pin number

Color

Purpose

 

 

 

1

Red

V+IN: Headset power (10-32 VDC). Use a 1/4 amp fuse or

 

 

a 1/2 amp circuit breaker.

 

 

 

2

Black

GND: System ground. Connect to the existing audio ground.

 

 

 

3

White

COMM L: Phone communication: Left.

 

 

 

4

Blue

COMM R: Phone communication: Right.

 

 

 

Note: For stereo operation, connect the left and right channels to their respective positions. For monaural operation, connect pins 3 and 4 together, and to the tip of the existing phone jack.

5

White

MIC HI: Microphone/Hi-audio. Connect to the portion of the

 

 

existing microphone jack that corresponds to the ring

 

 

position of a headset microphone plug. Do not connect to

 

 

the tip (PTT) segment.

 

 

 

6

White/

MIC LO: Microphone/Lo-ground. Connect to the portion of

 

Blue

the microphone jack that corresponds to the barrel position

 

 

of a headset microphone plug.

 

 

 

Note: If the microphone works on radio transmit but not through the intercom, check pin 6. It may be incorrectly wired to the PTT segment of the microphone jack.

Comm Shield

Black

Shield from Comm L and Comm R wire pair.

 

 

 

Mic Shield

Black

Shield from Mic Hi and Mic Lo wire pair.

 

 

 

Note: The wires connecting pins 3 and 4 and pins 5 and 6 are shielded, twisted pairs with a black wire shield termination exiting each pair. If the existing wiring is not shielded, connect the shields to the existing audio wiring shields, or connect the shield from Comm L and Comm R wire pair to audio ground.

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Bose A20 manual Details on making the connections, Helicopter U174 connection diagram

A20 specifications

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