(d)  
Install the control knobs.

 S 712-017
 (2)  Do a test of the lightplate:
 (a)
Supply electrical power (Ref 24-22-00/201).

 (b)  
Turn the lightplate control knob full clockwise.

 (c)  
Make sure all areas of the lightplate come on.

 S 862-019
 (3)  Remove electrical power if it is not necessary
 (Ref 24-22-00/201).

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BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
747-400
MAINTENANCE MANUAL

ELECTRICAL CONNECTOR LOCATION

FACEPLATE MOUNTING SCREW (4)
CIRCUIT BOARD
BACK
(EXAMPLE)

Lightplate Assembly
Figure 201

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BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
 1.

2.

3.

4.

A
747-400 MAINTENANCE MANUAL
 MASTER DIM AND TEST - DESCRIPTION AND OPERATION
_______________________________________________
General
_______
 A.  The master dim and test consists of a control switch and module, instrument panel indicator lights and pushbutton switch legends.
 B.  The pilots master dim and test provides a choice of two instrument panel indicator light intensities (bright or dim) and a method of testing the indicator lamps. The choice of a dim, bright or test function is made by setting the IND LTS switch to the desired position.
 C.  Instrument panel lighted pushbutton switches contain two illuminated legends. Each legend, illuminated by an independent two lamp circuit, is supplied electrical power from different sources.
 D.  For more data about this lighting system, refer to these sources:
 (1) SSM 33-12-01 thru 33-12-99
 (2) WDM 33-12-11 thru 33-12-99Master Dim and Test Control Module
__________________________________
 A.  The master dim and test control module is a card file of printed circuit cards that contain control relays and solid-state dimmers. The relays are used to add dimmer cards in series with the indicator lamp voltage source and to switch grounds onto indicator lamp test circuits. Master dim and test module relays are operated when the indicator light switch is set to the dim or test position.
 B.  The master dim and test module is mounted on the aft top surface of the P6 panel. Access to the master dim and test module is accomplished by opening an access panel at the rear of the closet wall panel above the P6 panel.
Indicator Lights
________________
 A.  The standard indicator has a 1/2 x 1 inch lens for nomenclature and is mounted directly to its panel. They are arranged individually or in groups. Indicator assemblies are of a modular construction, consisting of two diodes, two lamps and a fuse. The use of two lamps provides added reliability in the event of failure of one lamp. The two diodes isolate the indicator test circuit from the system fault circuit. The fuse provides circuit protection and prevents other indicator lights from being made operational in the event of an individual test light module malfunction.
Lighted Pushbutton Switches
___________________________
 A.  Instrument panel lighted pushbutton switches contain two illuminated legends. Lamps in the lighted legend identifying a system fault or function are supplied power from the master dim and test module. The module can be controlled for either bright or dim lamp illumination, or to conduct lamp testing by setting the IND LTS switch on the pilots' P5 overhead panel to the desired position.
 B.  Lighted pushbutton switch legends that indicate system status or switch positions are not controlled nor operated by the master dim and test module. Power is supplied from an independent dimmer control (Ref 33-11-00).
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