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Hughes JVC Projector 230 Sc Service Manual

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    							Chapter 2---System Description
    Model 230 Service Manual2-19
    R
    G
    B
    /H
    /SELECT Comp
    Y in
    C in
    IIC_CLK
    IIC_DATA
    +5.1V
    +15VB2
    B4
    B6
    B8
    B12 B13
    A13
    B16
    B15
    Pin callouts are to P12, P14, 
    or P18, depending on which
    VIC slot is being used.
    /V
    B10
    Figure 2-9.   Quad Standard Decoder I/O Diagram.
    LED Indication
    There are two LEDs on this VIC. The LED on the right side of the board glows
    when Composite Video is selected and the LED on the left glows when S-Video
    is selected. Only one LED can light at one time.
    IIC Interface
    The Quad Standard Decoder VIC is controlled by the serial bus interface. The
    IIC bus comes from the System Controller Board through the Backplane Board.
    All required adjustments for this board are provided via the IIC serial bus
    interface. The information transferred over the IIC bus is indicated below (I =
    input to YPbPr_VIC, and O = output of YPbPr_VIC). The selection of this VIC is
    accomplished through the IIC control bus which provides the /SEL_VIC signal.
    Table 2-6.  Quad Standard Decoder VIC IIC Interface
    I/O INFORMATION DESCRIPTION
    I SOURCE Selects input source (Composite Video or S-
    Video)
    I STANDARD Selects signal standard
    (AUTO/NTSC/PAL/SECAM/4.43NTSC) 
    						
    							Chapter 2---System Description
    2-20Model 230 Service Manual
    I TINT Data for adjustment of Hue
    I COLOR Data for adjustment of color
    I SHARP Data for adjustment of Sharpness
    I VTR Selection of VTR mode
    O VNR Selection of Video Noise Reduction mode
    Quad Standard Decoder VIC I/O
    This section provides a description of the inputs to and outputs from the Quad
    Standard Decoder VIC. The I/O descriptions are arranged by the
    source/destination of the signal. The format used is such that the assembly
    communicated with is used as the primary heading of each group of signals.
    Those signals are further subdivided into inputs and outputs. Input refers to an
    Input to the VIC, output refers to an output from the VIC.
    Table 2-7.   Quad Standard Decoder VIC Signals
    PROJECTOR INPUTS
    INPUT DESCRIPTION
    Composite V Video input signals-about 0.7 to 1 VPP
    S-Video Video input signal-about 0.7 to 1 VPP for Luminance and about .3-.6
    VPP for Chrominance (Burst)
    VIDEO PROCESSOR BOARD
    OUTPUT DESCRIPTION
    /SELECT Selection indicator for VIC. Low indicates the Quad VIC is selected.
    RED
    GRN
    BLUVideo signals. about 0.7 to 1 VPP
    H, V Horizontal/vertical sync signals, about 1-1.25 VPP
    SYSTEM CONTROLLER BOARD
    INPUTS DESCRIPTION
    IIC_CLK IIC clock line. Unidirectional clock line for control of synchronous
    data transfer over the IIC bus interface.
    IIC_DATA IIC data line. Bidirectional serial line for synchronous data transfer
    between System Control Board and the VIC. 
    						
    							Chapter 2---System Description
    Model 230 Service Manual2-21
    LOW VOLTAGE POWER SUPPLY
    INPUTS DESCRIPTION
    +5.1 V +5.1 V supply for use by The Quad Decoder VIC.
    +15 V + 15 V supply for use by the Quad Decoder VIC.
    Interlocks and protection
    None
    2.3.4  Video Processor PCB
    The Video Processor Board (VPB) is the bottom-most card (see Figure 5-1) in
    the card cage. It is connected directly to the Backplane board through 2
    connectors. When an external signal is being received, the VPB provides
    Horizontal Sync, Vertical Sync, and Green Sync signals to the Raster Timing
    Generator (RTG) board. It also provides three primary color signals, and G2, G1
    bias and DC RESTORE control signals to the Video Amplifier Board (VAB).
    The following functions are provided by the VPB:
    •  Video signal input and multiplexing
    •  Sync signal stripping
    •  Overlay signal multiplexing
    •  Brightness and Contrast control, and DC RESTORE
    •  Video signal gamma correction
    •  Sensitivity and Threshold signal input and control
    •  Automatic limiting for Contrast, G2, and internal video
    The Video Processor I/O diagram and the list of inputs and outputs provide
    information to allow the technician to perform module-level troubleshooting. 
    						
    							Chapter 2---System Description
    2-22Model 230 Service Manual
    B31   RED_VIC#1
    B29   RED_VIC#2
    B27   RED_VIC#3
    B23   GRN_VIC#2
    B21   GRN_VIC#3
    B19   BLU_VIC#1 B25   GRN_VIC#1
    B24  RED_THRESH
    B23  GRN_THRESH
    B22  BLU_THRESH B25  BLU_SENSB17   BLU_VIC#2
    B15   BLU_VIC#3
    B13   H_VIC#1
    B9     H_VIC#3
    B7     V_VIC#1
    B5     V_VIC#2B11   H_VIC#2
    B3     V_VIC#3
    GRN_G2    A20
    BLU_G2     A21 
    G1_BIAS    A11 RED_G2    A19 
    B20  GRN_BEAM
    B21  BLU_BEAM
    A13  /VA_OK (/HV_ENA) B19  RED_BEAM
    A8         +5.1V
    A9          +15V
        A10        -15V
    B12   IIC_CLK
    B13   IIC_DATA
    A12   /IIC_SINTB27  RED_SENS
    B26  GRN_SENS B29   OVERLAY
    B15   CLAMP
    B15   BLANKING
    REST ORE   B16  A2    /SEL_VIC#1
    B1    /SEL_VIC#2GRN_VIDEO   B4 RED_VIDEO    B2
    BLU_VIDEO    B6V_SYNC        A16 H_SYNC        A17
    GRN_SYNC  B17
    GRN INPUT  A28
    A1    /SEL_VIC#3
    B32   RED_OVER
    B31   GRN_OVER
    B30   BLU_OVER
    J17
    J16
    J16
    EXTERNAL
    VIDEO
    FROM
    SCB
    FROM RTG
    FROM
    SCB
    FROM/
    TO VAB
    FROM
    LVPSTO
    RTG
    TO
    VAB
    TO
    VAB
    TO
    VAB
    VIDEO
    PROCESSOR
    BOARD
    Figure 2-10.  Video Processor I/O Diagram
    IIC Interface
    The VPB communicates with the SCB via the IIC bus. The information
    transferred over the bus (as shown in Table 2-8) is indicated as follows (I = Input
    to the VPB, O = Output from the VPB):
    Table 2-8.  Video Processor IIC communication
    I/O INFORMATION DESCRIPTION
    I RED_CONT Red Contrast level
    I GRN_CONT Green Contrast level
    I BLU_CONT Blue Contrast level
    I BRIGHTNESS Brightness level
    I BEAM CURRENT Beam Current 
    						
    							Chapter 2---System Description
    Model 230 Service Manual2-23
    I RED_G2 Red G2 Control
    I GRN_G2 Green G2 Control
    I BLU_G2 Blue G2 Control
    I WHT_BOOST Gamma correction
    I BLK_BOOST Gamma correction
    I G1_BIAS G1 bias level
    O /VA_OK Issues to SCB that Video Amplifier
    is OK
    O BEAM_CURRENT Beam current control
    O OK_DETECT Issues to SCB that VPB is OK
    Video Processor I/O
    This section provides a comprehensive description of the inputs to and outputs
    from the VPB. The I/O descriptions in Table 2-9 are arranged by the
    source/destination of the signal. The format used is such that the assembly
    communicated with is used as the primary heading of each group of signals.
    Those signals are further subdivided into inputs and outputs. Inputs refers to an
    input to the VPB, while output refers to an output from the VPB.
    Table 2-9.  Video Processor I/O signals
    SYSTEM CONTROLLER BOARD
    INPUT DESCRIPTION
    RED_OVER Red signal of on-screen menu and/or internal test pattern
    GRN_OVER Similar to RED_OVER
    BLU_OVER Similar to RED_OVER
    OVERLAY Overlay control signal
    RED_SENS Sensitivity correction information for red. Real time data at
    0 volt to 1 volt.
    GRN_SENS Similar to RED_SENS 
    						
    							Chapter 2---System Description
    2-24Model 230 Service Manual
    BLU_SENS Similar to RED_SENS
    RED_THRES Threshold correction information for red. Real time data at
    0 Volt to 1 Volt
    GRN_THRES Similar to RED_THRES
    BLU_THRES Similar to RED_THRES
     I/O DESCRIPTION
    IIC_DATA IIC data line. Bidirectional serial line for synchronous data
    transfer between SCB and other circuit boards. See detailed
    description for list of signals transferred and data direction
    IIC_CLK IIC clock line. Unidirectional clock line for  control of
    synchronous data transfer over IIC bus.
    IIC_INT Interrupt output to SCB
    RASTER TIMING GENERATOR
    INPUT DESCRIPTION
    CLAMP Pulse signal input from the RTG board. Indicates the commanded
    timing and duration of the DC restore.
    BLANKING Pulse signal input from the RTG board. Indicates the commanded
    blanking interval during the scan.
    OUTPUT DESCRIPTION
    H_SYNC Horizontal sync signal to RTG board
    V_SYNC Vertical sync signal to RTG board
    GRN_SYNC Green sync signal to RTG board
    GRN_INPUT Green video signal to RTG board
    VIDEO AMPLIFIER
    INPUT DESCRIPTION
    RED_BEAM Voltage signal proportional to cathode current averaged
    over several horizontal lines in the red CRT. Voltage
    level is + mV/mA 
    						
    							Chapter 2---System Description
    Model 230 Service Manual2-25
    GRN_BEA Similar to RED_BEAM
    BLU_BEA Similar to RED_BEAM
    /VA_OK Issued from the VAB to indicate VAB working properly
    OUTPUT DESCRIPTION
    RED_VID Red video output. 0 Volt to 1 Volt.
    GRN_VID Similar to RED_VIDEO
    BLU_VIDE Similar to RED_VIDEO
    RESTOR DC RESTORE control signal. When this signal is asserted,
    DC level of the video signal is clamped at the proper value
    on the VAB.
    RED_G2 Red CRT G2 voltage adjust control signal.
    GRN_G2 Similar to RED_G2
     BLU_G2  Similar to RED_G2
     G1_BIAS  Control the adjustment of G1 voltage for all three CRTs
     EXTERNAL VIDEO
     INPUT  DESCRIPTION
     RED_VIC  Red video input from video input card #1
     GRN_VIC  Similar to RED_VIC #1
     BLU_VIC  Similar to RED_VIC #1
     RED_VIC  Similar to RED_VIC #1
     GRN_VIC  Similar to RED_VIC #1
     BLU_VIC  Similar to RED_VIC #1
     RED_VIC  Similar to RED_VIC #1
     GRN_VIC  Similar to RED_VIC #1
     BLU_VIC  Similar to RED_VIC #1
     H_VIC #1  Horizontal sync signal input from video input card #1
     H_VIC #2  Similar to H_VIC #1
     H_VIC #3  Similar to H_VIC #1
     V_VIC #1 Vertical sync signal input from video input card #1 
    						
    							Chapter 2---System Description
    2-26Model 230 Service Manual
     V_VIC #2  Similar to V_VIC #1
     V_VIC #3  Similar to V_VIC #1
    /SEL_VIC  Input signal from RGB VIC board which is used to select
     input video source from VIC #1.
     /SEL_VIC  Similar to /SEL_VIC #1
     /SEL_VIC  Similar to /SEL_VIC #1
    LOW VOLTAGE POWER SUPPLY
    INPUTS  DESCRIPTION
    + 5.1 volts  Power supply to digital components
    + 15 Volts  Power supply to analog components
    - 15 Volts  Power supply to analog components
    2.3.5   Video Amplifier
    The Video Amplifier Board (VAB) is located at the back side of the projector
    under the necks of the three CRTs. It contains three separate video amplifiers,
    one each for red, green, and blue. The outputs from these video amplifiers
    connect directly to the CRTs and provide all electrical connections to the CRTS
    except for the anode voltages.
    The following functions are provided by VAB:
    •  Amplification of video signals and driving the cathode of all three
    CRTs
    •  Sensing the cathode beam current for all three CRTs
    •  G1 regulator for all three CRTs
    •  Blanking drive section
    •  Phosphor protection for all three CRTs
    •  G2 regulator and adjustment of black level (screen) for all CRTs
    •  DC restoration for the video signals
    •  CRT interface for focus, heater voltage and ARC ground
    The Video Amplifier Board I/O diagram (Figure 2-11) and the list of Inputs and
    Outputs (Table 2-10) provide information for the technician to perform module
    level troubleshooting. 
    						
    							Chapter 2---System Description
    Model 230 Service Manual2-27
    G1 Regulator for three CRTs
    The input supply for the G1 grid of the CRTs is G1_SUPPLY and is about -200V.
    The VAB regulates this supply to about -80V to -30V. This supply can be
    adjusted by the G1_BIAS line. This adjustment provides the brightness control
    function. The G1_BIAS signal is an input of the VAB and is generated by the
    Video Processor Board. In the event of a failure, such as lack of deflection (a
    high on the /SWEEP_OK line), this output goes to the most negative value of the
    input supply (about -200V).
    G2 Regulator and  black level adjustment for CRTs
    The VAB also regulates the G2 grid of the CRTs. The supply for the G2 grids
    (about 1200V) is generated by the HVPS. This G2_SUPPLY is an input to the
    VAB. There are also three control inputs (RED_G2, GRN_G2, and BLU_G2).
    The G2 voltage of each CRT is adjusted individually by using these control lines.
    This adjustment provides black level control. The G2 output voltages are pulled
    down during shutdown mode.
    RED_VIDEO
    GRN_VIDEO
    BLU_VIDEO
    BLANKING
    G1 SUPPLY
    G1 BIAS
    RESTORE
    ARC_GND BLU_CATHODE 8
    BLU_GRID1 9
    BLU_GRID2 10BLU_BEAM 16
    BLU_HEAT- 7 BLU_HEAT+ 6
    ARC_GND 3 GRN _CATHODE 8
    GRN _GRID1 9
    GRN _GRID2 10 GRN_BEAM 14
    GRN _HEAT- 7GRN _HEAT+ 6
    ARC_GND 3RED _CATHODE  8
    RED _GRID1   9
    RED _GRID2  10RED_BEAM         12
    RED _HEAT-       7 RED _HEAT+   6
    ARC _GND    3
    2
    4
    6
    23
    21
    1
    2
    13      GRN_G2
    15      BLU_G2
    1     G2 SUPPLY 11      RED_G2
    19   /SWEEP_OK
    3     + 8OV
    7     + 15V
    5     + 6.2V
    9     -15V
    /VA_OK                18
    J83 J68
    J68
    J85
    J87 J68
    J68
    J84-1,
    J86-1,
    J88-1 J67
    J68
    J69
    J68 From
    VPB
    From VPB
    From HVPSFrom RTG
    From VPB
    From
    VPB
    From HVPS
    From HVDB
    From
    LVPS
    To  VPB
    To  RED
    CRT
    To  VPB
    To  GRN
    CRT
    To  VPB
    To  BLU
    CRT
    To  VPB
    To  
    HVPS
    VIDEO
    AMPLIFIER
    BOARD
    Figure 2-11.   Video Amplifier PCB, Block Diagram. 
    						
    							Chapter 2---System Description
    2-28Model 230 Service Manual
    CRT interface for Focus, heater voltages and ARC ground
    The three CRT sockets are part of the VAB. They provide the necessary
    interface for the input of the three CRTs. The Focus voltage for each color is
    connected directly to the socket of each CRT.
    The VAB provides ARC grounds for each CRT which are used to protect against
    arcing of the CRT anode supply.
    IIC Interface
    The VAB does not use the IIC interface. All adjustments are accomplished by the
    control lines coming from the Video Processor Board.
    The Video Amplifier Board I/O
    This section provides a description of the inputs to and outputs from the VAB.
    The I/O descriptions are arranged by the source/destination of the signal. The
    assembly communicated with is used as the primary heading of each group of
    signals. Those signals are subdivided into inputs and outputs. Input refers to an
    Input to the VAB, output refers to an output from the VAB.
    Table 2-10.  Video Amplifier I/O signals
    VIDEO PROCESSOR BOARD
    INPUTS DESCRIPTION
    RED_VIDEO
    GRN_VIDEO
    BLU_VIDEOVideo preamp signals. About 0.5 VPP
    G1_BIAS Brightness control line. 0 to 5 V DC
    RED_G2
    GRN_G2
    BLU_G2Black level (G2) control lines 0 to 3.1 V
    RESTORE Video DC restoration pulse. logic HC positive going  4% duty cycle
    OUTPUTS DESCRIPTION
    /VA_OK VAB status line. Low = good VAB. High = Bad VAB (This signal is
    called /HV_ENABLE at the HVPS).
    RED_BEAM
    GRN_BEAM
    BLU_BEAMCathode beam current lines. about 1 volt per 100 UA 
    						
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