COBHAM N301A-301 Installation And Operation Manual Supplement

Brand: COBHAM

Model: N301A-301

Type: Installation And Operation Manual Supplement

N301A-300 Audio Controller

SM45 Installation and Operation Manual Supplement

SM Supplement Rev: 1.01 May 17, 2012 Page i

ENG-FORM: 810-0111.DOT

CONFIDENTIAL AND PROPRIETARY TO COBHAM

Prepared By: Checked By: Approved By:

Revisions

Rev.

CR #

Date

Description of Change

1.01 DCA W12418 May 17, 2012 Added faceplate lighting specs.

1.00 Feb 23, 2012 Initial release

Geoff Melton

2012.05.17 

11:36:30 -07'00'

Barb Page

2012.05.2

4 

16:39:03 

-07'00'

Zack 

Pahlman

2012.05.

24 

17:20:47 

-07'00'

SEALED

2012.05.

29 

10:11:05 

-07'00'

Published on

June 01, 2012

N301A-300 Audio Controller

SM45 Installation and Operation Manual Supplement

SM Supplement Rev: 1.01 May 17, 2012 Page 1

ENG-FORM: 810-0111.DOT

CONFIDENTIAL AND PROPRIETARY TO COBHAM

This supplement contains installation and operation information that is unique to the N301A-300 Audio

Controller (N301A-300, N301A-301 and N310A-302). Installation and operation information common to

the N301A-000 base unit can be found in the SM45 Installation and Operation Manual.

Section 1 Description

The N301A-300 Audio Controller is identical to the N301A-000 with the following exceptions:

a) The backlight subassembly and TX LED annunciator are not installed.

b) The faceplate incorporates integral backlighting, TX annunciator and removable legends.

c) The MKR receive circuitry is replaced with HI/LOW IMPED discrete circuitry capable of sinking

≤100 mA at 30 VDC.

d) Rotary switch stop positions can be set by the customer.

Note: Refer to Figure 1 for identifiers (in italics) used on the N301A\300\403-0 Interconnect and

N301A\300\405-0 Connector Map drawings.

RADIO ICS

ICS

PVT

HOT VOX

RX-ON

EMER

NORM

N301A

LOW

IMPED

R S T

Figure 1

N301A-300 Front View

The N301A-300, N301A-301 and N301A-302 differ only in their faceplate lighting specifications, as

detailed below.

Model

Faceplate

Number

Color

Luminance

Backlighting Indicator Backlighting Indicator

N301A-300 55-35-205 Blue/White Green

1.0 ± 0.5

foot-lambert

15 ± 5

foot-lamberts

N301A-301 55-60-058 NVIS Green B NVIS Green B

N301A-302 55-55-032 NVIS Green A NVIS Green A

N301A-300 Audio Controller

SM45 Installation and Operation Manual Supplement

Page 2 May 17, 2012 SM Supplement Rev: 1.01

ENG-FORM: 810-0111.DOT

CONFIDENTIAL AND PROPRIETARY TO COBHAM

Section 2 Installation

For installation information and drawings, see SM45 Section 2. Select the appropriate revision of the

drawing for the serial number of the unit. The drawings specific to this derivative are listed below and can

be found at the end of this supplement.

2.1 Installation Drawings

DOCUMENT

REV.

DESCRIPTION

TYPE

SERIAL NO.

N301A\101\403-0 1.00 Audio Controller Interconnect All

N301A\101\405-0 1.00 Audio Controller Connector Map All

N301A\300\922-0 1.00 Audio Controller Mechanical Installation All

2.2 Legend Installation

Custom removable legends are to be ordered and installed by the customer.

Each N301A-300 requires a set of legends, either purchased individually (Part no. 55-06-xxxx, where

xxxx is the description of the legend, e.g., “COM1”) or as a legend kit (Part no. ACPLK-xxx). Each kit

consists of a number of printed legends and blanks (to suit customer requirements), and each legend

comes complete with a black gasket, either attached or loose in the bag.

If it is necessary to remove or replace a legend, carefully lever the legend away from the faceplate, and

insert the new or replacement legend as described above.

CAUTION

If the faceplate is damaged in any way during this process, light leakage

may occur, which will necessitate returning the unit to the manufacturer

for repair or replacement.

2.3 Stop Pin Installation

The N301A-300 is designed to enable the installer to adjust the number of positions that can be selected

on the rotary selector switch. The N301A is designed to be able to select up to 6 radio transmit positions

with the rotary selector switch. In applications where fewer than 6 radio selections are required, the

installer may wish to eliminate the ability of the selector switch to choose the unused positions. The

N301A-300 includes features that ease the adjustment of the number of rotary switch positions by the

installer. Use the procedure that follows to adjust the rotary switch.

When installing the legends for the first time, each legend must be fitted

with a black gasket to ensure uniformity of legend lighting. The gasket

fits into place on the back of the legend, but is easily dislodged or

damaged. Take particular care to ensure that it is properly positioned

before snapping the legend fully into place. If a replacement gasket is

required, the whole legend must be ordered.

Legend Gasket

N301A-300 Audio Controller

SM45 Installation and Operation Manual Supplement

SM Supplement Rev: 1.01 May 17, 2012 Page 3

ENG-FORM: 810-0111.DOT

CONFIDENTIAL AND PROPRIETARY TO COBHAM

To adjust the rotary switch stops, reference Parts List N301A\000\701-0 and Exploded View

N301A\000\904-0 in Maintenance Manual SM45 for the following procedure:

CAUTION

Parts are small and easily lost. Perform all operations at a work bench, not in the aircraft. Store all

parts in a plastic bag or other secure container while work is being performed.

CAUTION

Before removing knob set screws, ensure that Allen wrenches are not worn. Using an Allen

wrench with worn (rounded) corners will strip the screw head.

SHARP

CORNERS

ROUNDED

CORNERS

ACCEPTABLE UNACCEPTABLE

2.3.1 Using a 0.050” Allen wrench, remove knobs M6 from the front of the unit.

2.3.2 Using a 5/64” Allen wrench, remove knob M7 from the front of the unit.

2.3.3 Using a No. 1 Phillips screwdriver, remove pan head screws M8 from the front of the unit.

2.3.4 Remove faceplate.

2.3.5 Using a 9/16” hex socket or hollow shafted nut driver, remove hex nut and washer M211 from

rotary switch S201. The socket or nut driver must be at least 1” deep to accommodate the

shaft of the rotary switch.

N301A-300 Audio Controller

SM45 Installation and Operation Manual Supplement

Page 4 May 17, 2012 SM Supplement Rev: 1.01

ENG-FORM: 810-0111.DOT

CONFIDENTIAL AND PROPRIETARY TO COBHAM

HEX NUT

(P/O S201)

WASHER

M211

ROTARY

SWITCH

S201

CONNECTOR

J206

Figure 2

2.3.5 Up to eight rotary switch positions are available, numbered as shown on the faceplate in

Figure 3. (Rotary switch position numbers are shown for reference only.)

RADIO ICS

HOT VOX

RX-ON

EMER

NORM

N301A

LOW

IMPED

Figure 3

Identification of Rotary Switch Positions

(Rotary Switch position numbers shown for reference only)

2.3.6 Rotate the switch shaft clockwise as far as it will go.

2.3.7 Determine which rotary switch positions will be used on the faceplate to be installed.

2.3.8 Refer to Figure 4. Install a stop pin M212 in the hole whose number corresponds to the

lowest numbered rotary switch position that will be used.

2.3.9 Rotate the switch shaft counter-clockwise as far as it will go.

N301A-300 Audio Controller

SM45 Installation and Operation Manual Supplement

SM Supplement Rev: 1.01 May 17, 2012 Page 5

ENG-FORM: 810-0111.DOT

CONFIDENTIAL AND PROPRIETARY TO COBHAM

2.3.10 Install a stop pin M212 in the hole whose number corresponds to the highest numbered

rotary switch position plus one.

2.3.11 In the example shown in Figure 4, the rotary switch will be selectable for positions 1 through

8. Thus the stop pins are installed in positions 1 and 9.

ROTARY

SWITCH

S201

STOP PIN

M212 (2 PL)

WASHER

M211

HEX NUT

(P/O S201)

ROTARY SWITCH S201

STOP POSITIONS

Figure 4

Note: Factory setting is shown.

2.3.12 Reinstall washer M211 and hex nut on rotary switch S201 and tighten securely. Do not

overtighten.

2.3.13 Position faceplate M5 so that connector pins on the back of faceplate mate with J206

connector on the front of the unit (see Figure 2).

2.3.14 Fasten faceplate M5 to front of unit using pan head screws M8.

2.3.15 Rotate rotary switch S201 fully counter-clockwise. Using a 5/64” Allen wrench, install knob

M7 onto S201 selector switch shaft with the knob arrow pointing to the leftmost position used.

Tighten both set screws securely. Do not overtighten.

2.4.16 Using a 0.050” Allen wrench, install knobs M6 on the three volume control shafts. Rotate the

shafts fully counter-clockwise and install one knob M6 on each. Ensure the knob indicator

lines are pointing to the 7 o’clock position. Tighten both set screws securely on each knob.

Do not overtighten.

N301A-300 Audio Controller

SM45 Installation and Operation Manual Supplement

Page 6 May 17, 2012 SM Supplement Rev: 1.01

ENG-FORM: 810-0111.DOT

CONFIDENTIAL AND PROPRIETARY TO COBHAM

2.5 Replacement Hardware

If parts are lost, consult the table below for replacement information.

Description

Designator

Part Number

Source

Washer, Flat M211 25-20-030 Cobham

Stop Pin M212 85-99-591 Cobham

Knob M6 40-00-239 Cobham

Knob M7 40-00-533 Cobham

Set Screw,

0.112-40 X 3/16

For M6 Knob

(2 per knob)

MS51021-102 Generic

Set Screw,

0.164-32 X 3/16

For M7 Knob

(2 per knob)

MS51021-132 Generic

Hex Nut For S201 Rotary Switch Replacement not available. Hex nut is supplied

by switch manufacturer as part of switch.

Section 3 Operation

For operation information, see SM45 Section 3.

Supplement ends

COBHAM N301A-301 Installation And Operation Manual Supplement

COBHAM N301A-301 Installation And Operation Manual Supplement

COBHAM N301A-301 Installation And Operation Manual Supplement

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