Hughes Jvc 200 Projector Service Manual

Chapter 2---System Description 
2.3.10 Scan Reversal Board  
The Scan Reversal Board (SRB) is mounted vertically on the right 
side of the card cage.  
The following functions are provided by the SRB: 
• Reversal of scan in both horizontal and vertical axes 
• Horizontal width adjustment for each color (R, G &B) 
• Horizontal current feedback 
• Scan failure detection for all six main (horizontal and vertical) 
deflection amplifiers 
The Scan Reversal Board Input/Output diagram (Figure 2-16) and 
the...

  Chapter 2---System Description 
 
Figure 2-16.   Scan Reversal Board, Input/Output Diagram. 
Scan Reversal Board I /O 
This section describes the inputs to and outputs from the SRB. 
The I/O descriptions are arranged by the source/destination of the 
signal. The assembly communicated with is the primary heading 
of each group of signals. Those signals are subdivided into inputs 
and outputs. Input refers to an Input to the Scan Reversal Board. 
Output refers to an output from the Scan Reversal Board....

Chapter 2---System Description 
Table 2-15.  Scan Reversal Board I/O signals 
Horizontal / Vertical Deflection Board 
INPUTS DESCRIPTION 
H_OUT_ 
FLYBACK Horizontal output flyback pulse, about 800 VPP 
H_LOCK+ Horizontal interlock for yoke connectors. This should be about 5 
V when closed or 15 V when open. 
H_RED+ Output of horizontal red centering (also top of the red horiz yoke). 
About + 5 Vdc. 
H_GRN+ Output of horizontal green centering (also top of the green horiz 
yoke). About + 5 Vdc. 
H_BLU+...

  Chapter 2---System Description 
X_BLU+ Output of horizontal blue convergence amplifier 
Y_RED+ Output of vertical red convergence amplifier 
Y_GRN+ Output of vertical green convergence amplifier 
Y_BLU+ Output of vertical blue convergence amplifier 
OUTPUTS DESCRIPTION 
X_RED- Current feedback of horizontal red convergence amplifier 
X_GRN- Current feedback of horizontal green convergence amplifier 
X_BLU- Current feedback of horizontal blue convergence amplifier 
Y_RED- Current feedback of vertical...

Chapter 2---System Description 
V_GRN_YOK+ Top of green vertical yoke 
V_GRN_YOK- Bottom of green vertical yoke 
X_GRN_YOK+ Top of  green horizontal convergence yoke 
X_GRN_YOK- Bottom of green horizontal convergence yoke 
Y_GRN_YOK+ Top of green vertical convergence yoke 
Y_GRN_YOK- Bottom of green vertical convergence yoke- 
Blue Yoke Connector
NAME DESCRIPTION 
H_BLU_YOK+ Top of blue horizontal yoke 
H_BLU_YOK- Bottom of blue horizontal yoke 
BLU_LOCK+ Interlock for blue yoke. 5 V when closed or 15 V...

  Chapter 2---System Description 
2.3.11 Backplane PCB 
The Backplane PCB is the interface that connects the Power 
Supplies, VICs, PCBs, and other components together, either 
through a direct connection to a connector on the Backplane or 
through cables to connectors on the Backplane PCB. Signals are 
not modified in any way by the Backplane. It serves only as an 
interconnecting point. Refer to Figure 2-17 for a general idea of 
how the projector wiring is interconnected through the Backplane 
PCB....

Chapter 2---System Description 
2.4   Image Light Amplifier Technology 
Section 2.2 explained how the various units, including the ILA® 
assemblies, in the Optical System work together to produce the 
image on the screen. This section focuses mainly on how the ILA® 
assembly itself works. 
An Image Light Amplifier (ILA®) assembly (Figure 2-18) is a 
device that uses low-intensity images to modulate a high-intensity 
light through a liquid crystal layer. It is the key component in 
producing very bright,...

  Chapter 2---System Description 
High intensity light from a Xenon Arc Lamp is applied, through a 
prism (where it is polarized), to the output side of the ILA® 
assembly where the liquid crystal layer is located. The polarized 
light passing through the liquid crystal is modulated (changing the  
polarity of the light waves), in accordance with whatever image is 
on the input side of the ILA® assembly.  
The axis of the polarized light is proportional to the brightness on 
the input side of the ILA®...

Chapter 2---System Description 
Model 200 Service Manual   2-65 
  

Chapter 3---Service Adjustments 
3.0  Service Adjustments 
Contents 
3.1   Arc Lamp Focus and Alignment...............................................................3-1 
3.2   Arc Lamp Current Setting........................................................................\
3-4 
3.3   Electronic Module Tilt-up........................................................................\
.3-5 
3.4   ILA® Back Focus........................................................................\
.............3-5 
3.5...