outboard, right inboard, and upper center display units use draw-through cooling.
CAUTION:  DO NOT USE COMPRESSED AIR TO CLEAN THE SCREEN IN THE COOLING AIR INLET. COMPRESSED AIR WILL PUSH CONTAMINATION INTO THE DISPLAY UNIT AND CAUSE EQUIPMENT FAILURE.
Training Information Point
The six DUs are interchangeable. Because of the view angle limitations of LCD technology, the lower DU is 180 degrees from the other DUs. The lower center DU handle is at the top.
Training Information Point
CAUTION:  DO NOT USE ABRASIVE MATERIALS WHEN YOU CLEAN THE DISPLAY SURFACE. DO NOT TOUCH THE DISPLAY SURFACE WITH YOUR SKIN. THERE IS AN OPTICAL COATING ON THE DISPLAY SURFACE. YOUR SKIN OR ABRASIVE MATERIALS WILL CAUSE SCRATCHES IN THE OPTICAL COATING.
NOTE:  Remove the conductive plastic covers from the connectors before you install a DU.
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BEZEL LIGHT 
SENSOR 
BLOW THRU COOLING  LATCH MECHANISM 
COOLING AIR 
HOLES 
COOLING PIPE 
CONNECTION 
CONDUCTIVE COVERS 
ON CONNECTORS 
REMOVAL 
CDS - DISPLAY UNIT 
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CDS -- DU - FUNCTIONAL DESCRIPTION Display Unit
The display unit (DU) is a flat panel liquid crystal display (LCD) unit. The LCD makes a high resolution color image of the flight and engine data.
DU Rear Connector
All electrical interfaces go through one rear connector on the DU. The connector also has HIRF protection.
These are the inputs and outputs to the DU:
-28v dc power supply
-Coax inputs from coax couplers
-ARINC 429 status bus outputs to DEUs
-Program pins
-Power to and feedback from the remote light

sensors (outboard DUs only) -Power to and feedback from the manual brightness controls (all DUs).
Interconnect Board
The interconnect board applies all power, grounds, and signals necessary for transmission between functions.
EMI Filter
The +28v dc input power goes through the EMI filter before it goes to the interconnect board.
737-600/700/800/900 TRAINING MANUAL
Power Supply
The power supply supplies all the DU internal voltages. This does not include the LCD and heater voltages. The power supply changes +28v dc from the EMI filter into +5v, +/-15v, +30v, and +375v.
Input/Output Controller
The input/output controller (IOC) controls all digital data in and out of the DU. This includes the graphics image data from the DEU, the discrete data input for display unit identification, and the ARINC 429 status bus outputs.
The IOC also does the BITE monitoring functions for the DU.
Beamformer
The beamformer does a decompression of the graphics image data from the DEU to graphics image data for the LCD interface.
LCD Interface
The LCD interface changes image data to digital voltages and puts them in the LCD source drivers.
Voltage Reference
The voltage reference changes the digital voltage values from the LCD interface to analog voltage
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reference (VREF) voltages. The VREF voltage is a voltage that the LCD drivers use to control the image element on the LCD for different intensities.
LCD Drivers
The LCD drivers control the 1152 X 1152 color dots that make up the display.
Backlight Driver Assembly
The backlight driver assembly controls a fluorescent lamp. It also controls the lamp and LCD heater circuits. The backlight driver assembly keeps the lamp temperature at 60C. And the backlight driver assembly keeps the temperature for the LCD above 25C.
Lamp Assembly
The lamp assembly has a back surface that causes a reflection of the fluorescent lamp to increase the light output. It also has temperature sensors. When the lamp and LCD temperature are out of range, the backlight driver assembly adjusts the temperature.
Bezel Light Sensor
The bezel light sensor (BLS) senses incident light. The interconnect board changes the BLS signal to a digital value. This value goes on the ARINC 429 status buses back to the DEU for light intensity control.

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DISPLAY UNIT (TYP)

CDS - DU - FUNCTIONAL DESCRIPTION
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737-600/700/800/900 TRAINING MANUAL CDS -- BRIGHTNESS CONTROLS General
　
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