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747-400
MAINTENANCE MANUAL

 5.  Operation
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 A.  The indicator lamps on the pilots panels are 28-volt type. Primary dimming control is provided by a three-position IND LTS switch located on the pilots' overhead panel P5. The IND LTS switch TEST position is momentary only and must be manually held if a longer duration display is desired.
 B.  If the IND LTS switch is set to the BRT position, indicator lamps will be supplied with 28 volts.
 C.  Setting the IND LTS switch to DIM position operates module dim relays that add dimmer cards in series with indicator voltage sources. The dimmer cards reduce the indicator lamp supply voltage from 28 to 12 volts.
 D.  Setting the IND LTS switch to TEST position operates the test relays that provide electrical grounds to indicator test circuits. Indicator lamps will be illuminated in the bright mode.
 E.  If the IND LTS switch is held in the TEST position longer than 10 seconds, the indicator lights intensity displayed will be switched from bright to dim. The switching and delay for testing the dim function is provided by a time-delay relay contained in the master dim and test module.
 F.  If the IND LTS switch is released from TEST position, the time delay will be released and circuit operation will revert to normal.
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747-400 FAULT ISOLATION/MAINT MANUAL
MASTER DIM AND TEST
COMPONENT*  FIG. 102 SHT  QTY * ACCESS/AREA  AMM REFERENCE 
RELAY RELAY SWITCH - IND LTS DIM AND TEST CIRCUIT BREAKER LIGHT -INDICATOR PUSHBUTTON SWITCH MODULE - MASTER DIM AND TEST CARD - DIMMER  2 1 2 1  FLT COMPT CLOSET FLT COMPT, P5 FLT COMPT FLT COMPT FLT COMPT CLOSET FLT COMPT, P6 FLT COMPT CLOSET FLT COMPT, P6  * * 33-12-04 33-12-01 33-12-03 33-12-02 33-12-01 *

 * SEE THE SSM OR WDM FOR THE EQUIPMENT NUMBER, QUANTITY, AND LOCATION OF EACH COMPONENT IN THE  LIGHTING CIRCUIT
Master Dim and Test - Component Index
Figure 101

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747-400 FAULT ISOLATION/MAINT MANUAL
PILOTS OVERHEAD INDICATOR LIGHT PANEL, P5

MASTER DIM AND TEST MODULE
SEE

SHT 2
ON  w 
OFF  a 

PUSHBUTTON SWITCH-LIGHT
(EXAMPLE)

Master Dim and Test - Component Location
Figure 102 (Sheet 1)

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747-400 FAULT ISOLATION/MAINT MANUAL
GREEN LED INDICATORS ON DIMMER CARDS
(RIGHT SIDE VIEW)
DIMMER CARDS (EXAMPLE)
10 AMP 2PDT DIMMER RELAYS (EXAMPLE)
TIME DELAY RELAY (EXAMPLE)
MASTER DIM AND TEST MODULE (FRONT VIEW)
B
Master Dim and Test - Component Location (Detail from Sht 1)
Figure 102 (Sheet 2)

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747-400 MAINTENANCE MANUAL
 MASTER DIM AND TEST - ADJUSTMENT/TEST
_____________________________________
 1. General
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