ANNUNCIATOR LIGHT TEST AND DIMMING - DESCRIPTION AND OPERATION

** ON A/C NOT FOR ALL

1. General
Bulbs supplied with 5VAC-400Hz are used for the lighting of the sun readable lights in the cockpit. The current is delivered by the 115V/5V transformers.
Each light is parted in two sections ; each one has two 5V bulbs.
An annunciator light test switch permits illumination of all annunciators and therefore check of all lights.

** ON A/C NOT FOR ALL

2. Component Location

Annunciator Light Test and Dimming - Component Location

Annunciator Light Test and Dimming - Component Location ** ON A/C NOT FOR ALL

FIN	FUNCTIONAL DESIGNATION	PANEL	ZONE	ATA REF
** ON A/C ALL
1LP	BOARD-ANN LT TEST & INTFC	70VU	126	33-14-33
2LP	BOARD-ANN LT TEST & INTFC	70VU	126	33-14-33
3LP	BOARD-ANN LT TEST & INTFC	70VU	126	33-14-33
4LP	BOARD-ANN LT TEST & INTFC	70VU	126	33-14-33
5LP	BOARD-ANN LT TEST & INTFC	70VU	126	33-14-33
6LP	BOARD-ANN LT TEST & INTFC	70VU	126	33-14-33
7LP	BOARD-ANN LT TEST & INTFC	70VU	126	33-14-33
8LP	BOARD-ANN LT TEST & INTFC	70VU	126	33-14-33
9LP	BOARD-ANN LT TEST & INTFC	70VU	126	33-14-33
10LP	BOARD-ANN LT TEST & INTFC	70VU	126	33-14-33
11LP	BOARD-ANN LT TEST & INTFC	70VU	126	33-14-33
12LP	BOARD-ANN LT TEST & INTFC	70VU	126	33-14-33
18LP	BOARD-ANN LT TEST & INTFC	70VU	126	33-14-33
19LP	BOARD-ANN LT TEST & INTFC	70VU	126	33-14-33
20LP	BOARD-ANN LT TEST & INTFC	70VU	126	33-14-33
31LP	XFMR-ESS		211	33-14-51
33LP	SW-INT LT/ANN LT	25VU	210	33-14-00
35LP	XFMR-ESS		211	33-14-51
36LP	XFMR-SYS 2	120VU	212	33-14-51
37LP	XFMR-SYS 1	120VU	212	33-14-51

** ON A/C NOT FOR ALL

3. System Description

Annunciator Light Test and Dimming - Principle Diagram ** ON A/C NOT FOR ALL

Miniature lamps (115 mA, 5VAC) are used for the lighting of the annunciator lights mounted on the panels and instruments in the cockpit.
A relay (system) or internal contacts (case of ON-OFF position indication pushbutton switches) control illumination of each annunciator light. Four different busbars:

AC1 supply: 103XP
AC2 supply: 202XP
115VAC STAT INV BUS: 901XP
Essential supply: 801XP
supply the annunciator lights with 5VAC-400Hz through the transformers. In the case of emergency supply only busbar 901XP is serviceable.
The system comprises:

A. Four Identical Transformers
Each one is supplied with 115V-400Hz.
Each one is connected to a different busbar.
They supply 5VAC-400Hz for the annunciator lights installed on the overhead panel and on instrument panel and 6.3V voltage (full wave rectified) to supply the AUTO LAND, MASTER WARNING and CAUTION lights and Audio Control Panels (ACP).
The secondary winding of each transformer has:

7x5VAC outputs mounted in parallel; each one is protected by a delayed action fuse set at 4A,
2x6.3V outputs protected by the same type of fuse.

The primary winding of each transformer has two inputs to get the correct dimming level (DIM position).
If the 115V supply is switched over to either input we obtain at the secondary winding:

the 5VAC (BRT position),
the 3VAC (DIM position),
the 6.3VAC (BRT position) or 4.3VAC for rectified voltages (DIM position). The transformers 36LP and 37LP are housed in the panel 120VU and transformers 31LP and 35LP are mounted on the overhead panel.

B. Five Circuit Breakers

busbar 103XP (AC1) supplies transformer 37LP through the circuit breaker 26LP located on the circuit breaker panel 122VU,
busbar 202XP (AC2) supplies transformer 36LP through the circuit breaker 27LP located on the circuit breaker panel 122VU,
busbar 801XP supplies transformer 31LP through the circuit breaker 29LP located on the overhead panel 49VU,
busbar 801XP supplies transformer 35LP through the circuit breaker 29LP and the busbar 901XP provides emergency supply through the circuit breaker 28LP located on the circuit breaker panel 122VU,
busbar 206PP supplies the annunciator light test relay coils.

C. Switch 33LP
A switch with 3 positions: DIM, BRT, TEST is located on the overhead control and indicating panel 25VU.

D. Light Test Annunciators and Interface Boards
They are located in the avionics compartment in the annunciator light test unit 70VU:

4 are associated with the annunciator lights supplied by the AC1 system.
They are identified by FINs 1LP to 4LP.
seven are associated with the annunciator lights supplied by the essential generation. They are identified by FINs 5LP to 11LP.

Three are associated with the annunciator lights supplied by the AC2 generation.
They are identified by FINs 18LP to 20LP.
Each board comprises:

2 relays supplied by busbar 206PP with 28VDC through circuit breaker 30LP located on the rear circuit breaker panel 122VU.
These 2 relays serve for the annunciator light tests when the switch 33LP is in the TEST position.

10 relays supplied by the various A/C systems with 28VDC. They supply the annunciator light with 5VAC whereas the system data are supplied with 28VDC.

E. Four-Stage Relays
They are located in the relay box 103VU. They all are identified with a TEST placard. They serve for the test of the equipment annunciator lights (high intensity) or of other annunciator lights (ON - OFF).
The busbar 206PP supplies 28VDC to the coil of these relays through the circuit breaker 30LP located on the rear circuit breaker panel 122VU.

** ON A/C NOT FOR ALL

4. Operational/Control and Indicating

External Power Panel 108VU

A. Annunciator Light Test for the External Power Panel 108VU
The LIGHT TEST pushbutton switch 34LP on the panel 108VU serves to test the EXT PWR/NOT IN USE, EXT PWR/AVAIL, CKPT CALL, APU FIRE, ADIRU & AVNCS VENT and ELT (if installed) indicator lights.
The ADIRU & AVNCS VENT caution light is supplied from the 28VDC HOT BUS 704PP through the circuit breaker 6FP1 located on the circuit breaker panel 105VU.
The EXT PWR/NOT IN USE, EXT PWR/AVAIL, CKPT CALL and APU FIRE indicator lights are supplied from the 28VDC BUSBAR 1IWPP through the circuit breaker 4XG located on the circuit breaker panel 122VU.
The ELT indicator light is supplied from the 28VDC HOT BUS 702PP through the circuit breaker 2WC located on the circuit breaker panel 121VU (if installed).
If ground power is not available, the ADIRU & AVNCS VENT and ELT (if installed) indicator lights can be tested.
If ground power is available, the EXT PWR/NOT IN USE, EXT PWR/AVAIL, CKPT CALL, APU FIRE, ADIRU & AVNCS VENT and ELT (if installed) indicator lights can be tested.

[Rev.10 from 2021] 2026.04.01 05:16:00 UTC