Hughes JVC Projector 250 Service Manual

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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 four sets of RGBHV inputs. It has a
Multiplexer (switcher) that selects one set of RGBHV inputs at a time. The VIC
receives a SELECT command from the System Controller PCB through the IIC
data bus to activate the VIC and select an input. The VIC sends a /SEL_VIC
signal to an internal Input Switcher (Mux) on the Video Processor PCB. This tells
the Video Processor PCB which VIC is selected and which set of inputs is
selected. An operator selects the VIC and input in the Channels Menu (see section
4-6 in the User’s Guide).
A green LED illuminates when the VIC is selected.
The 4-Input (Quad) RGBHV VIC uses two VIC slots.
4-Input (Quad) RGBHV VIC - Service Adjustments
There are no service adjustments on the RGBHV VIC
4-Input (Quad) RGBHV VIC - Remove and Replace
Tools Needed
#0 Posi-drive Phillips-head screwdriver
Parts Needed
4-Input (Quad) RGBHV VIC  p/n 103668
To remove the RGBHV VIC:
1. Power off the projector by IR Remote or PC, and allow the cooling fans to
run until they shut off automatically.
2. Turn the AC Circuit Breaker to the OFF position and unplug the AC
Power Cord.
3. It is not necessary to remove the rear cover.
4. Disconnect the all the red, green blue, horizontal and vertical input BNC
cables from the VIC.
5. Remove the four retaining screws from the faceplate of the VIC.
6. Pull the VIC out of the Electronics Module.
7. Reverse the process to install the VIC. 
						

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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 component input or YPbPr input
!
 LED indication
!
 IIC serial bus interface
Figure 5-37  
YPbPr VIC I/O Diagram. 
						

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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 circuitry
+5.1 V - power for digital circuitry
+5.1 V Stdby (not used)
IIC CLK - IIC clock line
IIC DATA - IIC data line
IIC SINT - IIC interrupt line
YPbPr VIC - Outputs
RED_VIC - red image to Video Processor PCB (0.7-1.0 Vpp).
GRN_VIC - green image to signal Video Processor PCB (0.7-1.0 Vpp).
BLU_VIC - blue image to Video Processor PCB (0.7-1.0 Vpp).
SYNC - composite horizontal and vertical sync to Video Processor PCB.
/SEL_VIC - VIC select line to Video Processor PCB.
YPbPr VIC - Operation
This VIC accepts two input signal formats, YPbPr and GBR signals. The YPbPr
VIC converts either input signal format to the RGB format. The selection of the
VIC and inputs is controlled by the System Controller Board via the IIC serial bus 
						

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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 mode with the Tint,
Color, and Sharpness options in the Picture Menu. The Tint control adjusts the
tint of the colors displayed. Facial tones will vary from slightly green at zero to
slightly red at 255. The Color control adjusts the amount of color saturation or
color intensity. Colors will be almost grayscale at zero and very saturated at 255.
The Sharpness control adjusts the high frequency peaking of the black and white
details. These options are not available and are disabled in the RGB mode.
The YPbPr VIC has two LEDs. The RGB LED illuminates green when the
YPbPr_VIC is in RGB input mode. The YPbPr LED illuminates green when the
YPbPr_VIC is in YPbPr input mode. Only one LED will be illuminated at one
time. Neither LED is illuminated when the YPbPr_VIC is not selected as the input
to projector.
YPbPr VIC - Service Adjustments
There are no physical service adjustments to the YPbPr VIC
YPbPr VIC - Remove and Replace
Tools Needed
#0 Pozi-drive Phillips-head screwdriver
Parts Needed
YPbPr VIC  p/n 106340
To remove the YPbPr VIC:
1. Power off the projector by IR Remote or PC, and allow the cooling fans to
run until they shut off automatically.
2. Turn the AC Circuit Breaker to the OFF position and unplug the AC
Power Cord.
3. It is not necessary to remove the rear cover.
4. Disconnect the input BNC cables from the VIC.
5. Remove the two retaining screws from the faceplate of the VIC.
6. Pull the VIC out of the Electronics Module.
7. Reverse the process to install the VIC. 
						

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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 of composite and S-image signals to RGB image signals
!
 Separation of syncs from the input signal
!
 Tint, sharpness, and color adjustment
!
 LED indication of Composite or S-video
!
 IIC serial bus interface
Figure 5-39  
Quad Standard Decoder VIC faceplate.
Figure 5-40  
Quad Standard Decoder I/O Diagram. 
						

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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 - red image to Video Processor PCB (0.7-1.0 Vpp).
GRN_VIC - green image to signal Video Processor PCB (0.7-1.0 Vpp).
BLU_VIC - blue image to Video Processor PCB (0.7-1.0 Vpp).
SYNC - composite horizontal and vertical sync to Video Processor PCB.
/SEL_VIC - VIC select line to Video Processor PCB.
Quad Standard Decoder VIC - Operation
The Quad Standard Decoder VIC accepts two source input formats, Composite
and S-image. The Composite format combines the image (red, green, and blue)
signals and the sync pulses (horizontal and vertical) into one signal. The S-image
signal has two separate inputs, one contains the color information (Cin), and the
other input contains the black and white information (Yin). The sync pulses are
combined with the Yin. Both the Composite and S-image formats may be in a
variety of different signal standards such as NTSC (U.S.), PAL (European),
SECAM, or 4.43 NTSC. The VIC accepts all of these standards. The Quad
Standard Decoder VIC converts Composite and S-image to the RGBHV format.
The selection of the VIC and inputs is controlled by the System Controller Board
via the IIC serial bus interface. An operator selects the VIC and input in the
Channels Menu (see section 4-6 in the User’s Guide).
The Quad Standard Decoder VIC strips the sync pulses that are combined with
the black and white information (Yin) and sends them to the Video Processor
PCB as a composite sync signal. The Video Processor PCB separates the
composite sync signal and sends it to the Raster Timing Generator PCB.
The Quad Standard Decoder VIC also does signal processing with the Tint, Color,
and Sharpness options in the Picture Menu. The Tint control adjusts the tint of the
colors displayed. Facial tones will vary from slightly green at zero to slightly red
at 255. The Color control adjusts the amount of color saturation or color intensity.
Colors will be almost grayscale at zero and very saturated at 255. The Sharpness
control adjusts the high frequency peaking of the black and white details.
The Quad Standard Decoder VIC has two LEDs. The Composite LED illuminates
green when the Composite input is selected. The S-image LED illuminates green 
						

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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  p/n 103545
To remove the Quad Standard Decoder VIC:
1. Power off the projector by IR Remote or PC, and allow the cooling fans to
run until they shut off automatically.
2. Turn the AC Circuit Breaker to the OFF position and unplug the AC
Power Cord.
3. It is not necessary to remove the rear cover.
4. Disconnect the input BNC cables from the VIC.
5. Remove the two retaining screws from the faceplate of the VIC.
6. Pull the VIC out of the Electronics Module.
7. Reverse the process to install the VIC.
Quad Standard Decoder/Line Doubler VIC
The Quad Standard Decoder/Line Doubler VIC is very similar in function to the
Quad Standard Decoder VIC. It accepts the same two source input formats,
Composite and S-image and processes them exactly the same. It has two LEDs
that function exactly as the Quad Standard Decoder VIC. The inputs, outputs and
signal processing are also the same. Selecting the VIC is done in the Channels
Menu, the same as the other VICs. There are two distinguishing differences. The
Quad Standard Decoder/Line Doubler VIC doubles the horizontal scan frequency
of the input source. The other difference is that the Quad Standard Decoder/Line
Doubler VIC takes up two VIC slots.
The Line Doubler section doubles the horizontal scan frequency of the input
source. As an example, if the input source is a Composite signal in NTSC, which
has a line rate of about 15 .75 kHz, the Quad Standard Decoder/Line Doubler VIC
doubles the line rate to 31.5 kHz. This provides a much cleaner display on the
screen.
The Quad Standard Decoder/Line Doubler VIC takes two VIC slots, even though
the faceplate only covers on space. Some of the components prevent it from
fitting into one VIC slot. When the Quad Standard Decoder/Line Doubler VIC is 
						

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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 cabling.
Troubleshooting on the Backplane PCB
The connectors on the Backplane PCB provide one of the more accessible places
to probe voltages and signals that may be useful for troubleshooting purposes (see
Figure 5-43 and associated list of signals and voltages).
Figure 5-42  
Backplane Diagram (left side). 
						

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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 Supply (9)  (28)
Pin # Signal or Voltage (
see Figure 5-44)
2  /LAMP_LIT Pin # Signal or Voltage
3 /LAMP_OK 1 +5.1 V Stdby
4 /LAMP_ENA 2 GND
5 /COVER_ON 3 /COVER_ON
1, 6 GND