Hughes JVC Projector 250 Sc Service Manual

Chapter 5---Electronics
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4-Input (Quad) RGBHV VIC - Outputs
RED_VIC - red image to the Video Processor PCB (0.7-1.0 Vpp).
GRN_VIC - green image to the Video Processor PCB (0.7-1.0 Vpp).
BLU_VIC - blue image to the Video Processor PCB (0.7-1.0 Vpp).
H_VIC - horizontal sync to the Video Processor PCB
V_VIC - vertical sync to the Video Processor PCB
/SEL_VIC - VIC select line to the Video Processor PCB
4-Input (Quad) RGBHV VIC - Operation
The 4-Input (Quad) RGBHV VIC accepts...

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YPbPr VIC
This decoder video input card (YPbPr_VIC) contains three BNC input connectors
that can be used for two different inputs, YPbPr or GBR. The YPbPr PCB
converts these component signals to RGB type image signals.
YPbPr VIC - Main  Functions
!
 Image input and output buffers
!
 Conversion of YPbPr signal format to RGB signals format
!
 Separation of syncs from the Y/G input signal
!
 Hue, sharpness, gamma, and color adjustment
!
 Selection of RGB...

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Figure 5-38  
YPbPr VIC faceplate.
YPbPr VIC - Inputs
YPbPr Inputs
Y - green image input with composite horizontal and vertical sync (0.7-1 Vpp)
Pb - blue image input for YPbPr (0.7-1 Vpp)
Pr - red image input for YPbPr (0.7-1 Vpp)
GBR Inputs
Grn - green image input with composite horizontal and vertical sync (0.7-1 Vpp)
Blu - blue image input (0.7-1 Vpp)
Red - red image input (0.7-1 Vpp)
+15 V - power for analog circuitry
-15 V - power for analog...

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interface. An operator selects the VIC and input in the Channels Menu (see
section 4-6 in the User’s Guide).
The YPbPr VIC strips the sync pulses that are combined with the green image
signal (Y in YPbPr mode) and sends them to the Video Processor PCB as a
composite sync signal (H_SYNC). The Video Processor PCB separates the
composite sync signal and sends it to the Raster Timing Generator PCB.
The YPbPr VIC also does signal processing in the YPbPr...

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Quad Standard Decoder VIC
The Quad Standard Decoder VIC provides an interface for composite and
S-Video formats input. It contains three BNC input connectors, one for
Composite Video and two for S-Video (luminance and chrominance). This
decoder VIC converts Composite and S-image formats to RGBHV format.
Quad Standard Decoder VIC - Main Functions
!
 Select input source, Composite or S-video
!
 Select standard-AUTO/NTSC/PAL/SECAM/4.43NTSC
!
 Conversion...

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Quad Standard Decoder VIC - Inputs
Comp - input for Composite image signal includes sync pulses (.07-1 Vpp)
Yin - input for Luminance or brightness information of S-image (0.7-1 Vpp)
Cin  - input for Chrominance or color information of S-image (0.3-0.6 Vpp)
+15 V - power for analog circuitry
+5.1 V - power for digital circuitry
IIC CLK - IIC clock line
IIC DATA - IIC data line
IIC SINT - IIC interrupt line
Quad Standard Decoder VIC - Outputs
RED_VIC -...

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when the S-image input is selected. Only one LED will be illuminated at one
time. Neither LEDs will be illuminated when the Quad Standard Decoder VIC is
not selected as the input to projector.
Quad Standard Decoder VIC - Service Adjustments
There are no physical service adjustments to the Quad Standard Decoder VIC.
Quad Standard Decoder VIC - Remove and Replace
Tools Needed
#0 Pozi-drive Phillips-head screwdriver
Parts Needed
Quad Standard Decoder VIC...

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installed in the #2 or 3 VIC slot (it will not fit into the #1 slot), a blank face plate
must be installed above it. The blank faceplate is not included with the Quad
Standard Decoder/Line Doubler VIC unless it is installed at the factory. The part
number for the blank faceplate is p/n 102667.
Figure 5-41  
Quad Standard Decoder/Line Doubler VIC faceplate with blank
faceplate above it. 

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5.12 Backplane PCB
The Backplane PCB is the spine of the Electronics Module. Every major
electronic component in the Model 250 projector connects to and through the
Backplane PCB. It is hidden in the inside of the Electronics Module (see Figure
5-2). The System Controller PCB, Raster Timing Generator PCB, Video
Processor PCB and the three VICs are connected into it directly. All the other
PCBs and Power Supplies are connected through jumpers and...

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Figure 5-43  
Backplane Diagram (middle section).
The following is a list of pins that would be helpful for troubleshooting purposes.
Low Voltage Power Supply (J8) High Voltage Power Supply (J7)
Pin # Signal or Voltage Pin # Signal or Voltage
8 /LV_ENA 5 /HV_OK
9 /LV_OK 8 +80 V
10  +24 V_FANS 9 +15 V
11  _5.1 V Stdby 10 -15 V
12  +5.1 V 11 G1 SUPPLY
13 +6.2 V 12 /VA_OK
14 +15 V 1-4 GND
15 -15 V
16 +80 V
17 /COVER_ON
18 /FAN_ENA
1-7 GND
Arc Lamp Power...