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Hughes JVC Projector 230 Sc Service Manual

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    							Chapter 1---Introduction
    Model 230 Service Manual1-3
    RAM Random Access Memory
    RGB Red, Green and Blue
    RGBHV Red, Green, Blue, Horizontal, Vertical
    ROM Read Only Memory
    RTG Raster Timing Generator
    SCB System Controller Board
    SECAM Sequential couleur a memoire (sequencial 
    color with memory
    SRB Scan Reversal Board
    SYNC Synchronization
    TTL Transistor-Transistor Logic
    UL Underwriter Laboratories
    UV Ultraviolet
    VAB Video Amplifier Board
    VCO Voltage Controlled Oscillator
    VIC Video Input Card
    VIN Video Input
    VPB Video Processor Board
    VSYNC Vertical Sync
    VTR Video Tape Recorder
    YC Luminance/Chrominance 
    						
    							Chapter 1---Introduction
    1-4
    Model 230 Service Manual 
    						
    							Chapter 2---System Description
    Model 230 Service Manual2-1
    2.0   System Description
    Contents
    2.1   Introduction ..............................................................................................2-1
    2.2   Optical System .........................................................................................2-2
    2.2.1   Image Path ...................................................................................2-2
    2.2.2   Arc Lamp Light Path .....................................................................2-3
    2.3   Electronics System ...................................................................................2-6
    2.3.1   General Description ......................................................................2-6
    2.3.2   Power Supplies.............................................................................2-7
    2.3.3   Video Input Cards .........................................................................2-11
    2.3.4   Video Processor PCB ...................................................................2-21
    2.3.5   Video Amplifier PCB .....................................................................2-26
    2.3.6   System Controller PCB.................................................................2-30
    2.3.7   Raster Timing Generator PCB ......................................................2-37
    2.3.8   Horizontal/Vertical Deflection PCB ...............................................2-42
    2.3.9   Convergence/Deflection PCB .......................................................2-48
    2.3.10 Scan Reversal PCB ......................................................................2-54
    2.3.11 Backplane PCB ............................................................................2-59
    2.1   Introduction
    The assemblies and components in the Model 230 projector are contained
    mainly in the five sections below (refer to Figures 4-1 and 4-13 for physical
    locations of assemblies and components:
    •  The Optics Assembly Section is located at the front area of the projector. The
    Optics Assembly Section includes the Cold Mirror/IR Filter, (CAUTION!: The
    term cold mirror is used because the mirror passes infrared light and its
    reflection contains only cold light that does not transmit appreciable heat.
    As a result of the absorption of infrared heat radiation, cold mirrors can get
    very hot.), Second Condensing Lens Ultraviolet Filter, Dichroic Mirror
    Assembly, Prisms, Combining Prism, Image Mirrors, and the Zoom
    Projection Lens.
    •  The Arc Lamp Assembly section is located in the right front area of the unit. It
    contains the Xenon Arc Lamp, First Condensing Lens, and Blower.
    •  The Power Supply Section is located at the right front area of the projector
    below and to the rear of the Arc Lamp. It contains the Low Voltage Power
    Supply, the High Voltage Power Supply, and the Arc Lamp Power Supply.
    •  The Projector Electronics Section is located mainly in the back half of the
    projector. It consists of the Electronics Module that houses 6 of the
    electronics printed circuit boards used in the projector, and their associated 
    						
    							Chapter 2---System Description
    2-2Model 230 Service Manual
    cabling. It also contains the Backplane board which is used to electrically
    interconnect the printed circuit boards, power supplies and other units in the
    projector, and the Video Input Cards that interface with different kinds of
    input signals.
    •  The CRT Section is located beneath the electronics card cage and contains
    the 3 CRTs, 3 Relay Lenses, 3 ILA®s and the Video Amplifier Board.
    2.2   Optical System
    Introduction: The Model 230 Optics Assembly divides white light from the Arc
    Lamp into its three color components, Red, Green and Blue. This light is then
    modulated with the image signal to form three single color images. The light is
    then recombined at the 4P (combining) prism and transmitted through the
    projection lens to the projector screen. The explanation below is divided into two
    sections. The first section follows the image path from the CRT to the projector
    screen. The second section follows the high intensity light path from the Arc
    Lamp Ignitor to the ILA
    ® assemblies, where it combines with the image. The
    Red, Green, and Blue image and light paths are identical. Refer to Figure 2-1.
    CAUTION! The alignment of system optical components is
    critical. Replacement of individual mirrors or prisms requires removing the
    projector cover and must be performed only by Hughes-JVC Certified
    technicians. Consult the factory before removing or aligning any mirrors or
    prisms.
    2.2.1   Image Path
    CRT Assemblies: The three CRT/Yoke assemblies are located beneath the
    Electronics Module card cage. Two exhaust fans at the rear help cool the CRT
    assemblies. Each CRT is sent a red, green, or blue signal, but they do not emit a
    red, green, or blue color, as in traditional projectors. The CRTs are not used as a
    primary light source. The light output to the screen is the function of the Arc
    Lamp. The purpose of the CRTs is to generate an image and to control the
    amount of modulation the ILA® assemblies introduce on the light coming from
    the Arc Lamp. The Red, Green, and Blue image signals are routed to the CRTs
    from the Video Amplifier Board through the CRT socket connectors.
    Relay Lens: The relay lens picks up the image from the face of the CRT and
    focuses the image to the ILA® assembly.
    Image Light Amplifier (ILA®) Assembly: The CRT image is received from the
    relay lens onto the input side of the ILA® assembly. The input and output sides
    of the ILA® assembly are isolated from each other electrically and optically but
    are coupled electrostatically.
    At the same time as the image is received at the input side of the ILA®
    assembly, the output side of the ILA® assembly is receiving high intensity light
    from the arc lamp through the prism. This high intensity light is modulated 
    						
    							Chapter 2---System Description
    Model 230 Service Manual2-3
    (changing its polarization) by the signal on the input side of the ILA® assembly.
    The light is then reflected back from the output side of the ILA® assembly, then
    travels through the prism to be picked up by the projection lens.
    NOTE: The prism reflects horizontally polarized light and passes vertically
    polarized light. Light from the arc lamp is polarized horizontally and reflects from
    the prism into the ILA® assembly then back out again, after being modulated by
    the image signal into vertically polarized light. The vertically polarized light then
    passes through the prism to the projector lens. In this manner the ILA®
    assembly combines the image from the CRT with the high intensity light from the
    arc lamp. Thus, the maximum brightness of the screen image is not dependent
    on the brightness of the CRT, but on the light from the arc lamp.
    Polarizing Prism: The polarizing prism receives the high intensity light from the
    xenon arc lamp and polarizes the light horizontally. The prism reflects virtually all
    of this light toward the ILA® assembly. This light is then modulated (altered) into
    a vertical plane by the image on the input side of the ILA® assembly and then
    reflected back into the same prism. Since the prism reflects only horizontal light
    and passes vertical light, this high intensity, vertically polarized image goes
    straight through the prism toward the Combining Prism. Light that is not
    completely polarized horizontally or vertically passes through the prism in varying
    degrees of brightness, according to how polarized it is (fully polarized light
    resulting in maximum brightness on the screen).
    Image Mirror: The Image Mirrors direct the blue and red images toward the
    Combining Prism.
    Combining (4P) Prism: The combining prism consists of separate prisms that
    polarize each of the three high intensity signals and direct them toward the
    projection lens.
    Projection Lens: The Projection Lens picks up the high intensity image from the
    Combining Prism and transmits it to the projector screen.
    2.2.2   Arc Lamp Light Path
    The Arc Lamp assembly produces the high intensity light used to transmit bright
    images to the screen. It consists of a Xenon Arc Lamp containing xenon gas
    under pressure, a Condensing Lens, an Ignitor assembly that provides the spark
    to light the arc lamp, a Laser Power Supply to provide the boost voltage to the
    Ignitor. An exhaust fan and blower help keep the arc lamp cool. The description
    below follows the sequence of the light path. (See Figure 2-1).
    Ignitor and Laser Power Supply: The Laser Power Supply provides a boost
    voltage through a spark gap to the Ignitor circuit which then provides a
    momentary High Voltage, (about 32 KV), to excite the xenon gases inside the
    Xenon Arc Lamp. After the arc lamp ignites, it is maintained ON by high current
    and low-voltage (55-70 amps and +20-23 volts).
    WARNING!!!  The Xenon Arc Lamp produces high intensity
    white, ultraviolet and infrared light capable of severe eye injury. Never look 
    						
    							Chapter 2---System Description
    2-4Model 230 Service Manual
    directly at or touch the Xenon Arc Lamp. Service should be performed by
    Hughes-JVC certified technicians only.
    Xenon Arc Lamp/Condensing Lens: High pressure, ionized xenon gas
    supports a high-current electrical arc to produce the intense, white light used in
    the Model 230 projector.
    First Condensing Lens: The high intensity light output from the Xenon Arc
    Lamp goes through the First Condensing Lens (attached to the rear of the Arc
    Lamp housing) where the light beam is condensed and directed toward the Cold
    Mirror/IR Filter.
    Cold Mirror/IR Filter: The Cold Mirror/IR Filter removes most of the IR light and
    directs the light beam toward the Second Condensing Lens.
    Second Condensing Lens/UV Filter: Final condensing for the light beam is
    provided by the Second Condensing Lens. Ultraviolet light is filtered out by the
    UV Filter.
    The high intensity light beam continues toward the Dichroic Mirror Assembly.
    Thus, most of the IR and UV light is filtered out before the light beam enters the
    more sensitive portions of the optics, leaving only the visible portion.
    Dichroic Mirror Assembly: The condensed and filtered white light beam enters
    the Dichroic Mirror Assembly which separates (dichroic mirrors reflect only one
    color and pass all others) the light into its Red, Green and Blue components.
    Prepolarizers and Polarizing Prisms: Each individual light beam is polarized
    (directed) toward its own Polarizing Prism where it is directed toward the output
    side of its ILA
    ® Assembly and combined with the signal from the input side of the
    ILA® Assembly.
    Each of these three light beams independently combine with the image in their
    own (Red, Green or Blue) color systems at the ILA
    ® assemblies as described in
    Section 2.2.1, Image Path. 
    						
    							Chapter 2---System Description
    Model 230 Service Manual2-5
    Figure 2-1.  Optical System Block Diagram 
    						
    							Chapter 2---System Description
    2-6Model 230 Service Manual
    2.3   Electronics System
    2.3.1 General Description
    The Model 230 Electronics System includes nine printed circuit assemblies. They
    provide all the controlling voltages and signals to adjust and correct picture
    settings, geometry, convergence, and shading (see Chapter 4 of the User’s
    Guide). The Electronics System also controls video and sync input signals, LED
    displays on PCBs at the rear and side of the projector, two RS-232
    communications ports, and two IR receivers for remote control of the projector.
    The descriptions in this portion of the manual are based on an overall Electronics
    System block diagram and simplified block diagrams for each of the nine printed
    circuit assemblies. The diagrams and descriptions serve two purposes; first, to
    provide the technician with an overall grasp of how the system works and how
    each assembly works with other assemblies in the system, second, to provide
    the technician with enough information to troubleshoot to the assembly level, if
    needed.
    Figure 2-2 provides an overall System Block Diagram to show how the Optical
    System, Arc Lamp, and Electronics System combine to provide the bright screen
    image.
    VIDEO INPUT
    CARDS
    SCAN REVERSAL
    BOARD
    VIDEO 
    PROCESSOR
    BOARD
    SYSTEM
    CONTROLLER BOARD
    RASTER TIMING
    GENERATOR
    CONVERGENCE 
    DEFLECTION BOARD
    HORIZONTAL
    VERTICAL 
    DEFLECTION BOARD
    LINE
    FILTER AC
    INPUT
    ARC LAMP
    POWER SUPPLY
    LOW VOLTAGE
    POWER SUPPLY
    VIDEO AMP
    G2
    ELECTRONICS MODULE
    IGNITOR
    TO CRTS
    FOCUSHIGH 
    VOLTAGEHIGH VOLAGE
    POWER SUPPLY
    CRTS
    RELAY
    LENSES
    PROJECTION
    LENS
    OPTICS MODULE
    ILA’S
    DICHROIC
    MIRROR
    ASSEMBLY UV FILTER/
    SECOND 
    CONDENSING LENS COLD MIRROR/
    IR FILTER
    ARC LAMP
    BACKPLANE 
    RING COLLECTOR
    FIRST
    CONDENSING
    LENS
    Figure 2-2.   Model 
    230 System Block Diagram 
    						
    							Chapter 2---System Description
    Model 230 Service Manual2-7
    2.3.2   Power Supplies
    The Model 230 includes three power supply assemblies.
    •  Low Voltage Power Supply
    •  Arc Lamp Power Supply
    •  High Voltage Power Supply
    Low Voltage Power Supply (LVPS)
    P75P76
    1
    3
    51-7
    8
    9
    10
    11
    12
    13
    14
    15
    16
    17
    18To P8 on
    Backplane AC
    INPUTLine
    Earth
    NeutralLV Ret
    /LV_ENA
    /LV_OK
    +24v Fans
    +5.1v STBY
    +5.1v
    +6.2v
    +15V
    -15v
    +80V
    /COVER_ON
    /FAN_ENA
    Figure 2-3.   LVPS Input/Output Diagram
    Main Functions:
    •  Provide all the low voltages needed by the projector.
    •  Provide standby power when the projector is OFF.
    •  Provide power for all cooling fans.
    Inputs:
    The Low Voltage Power Supply receives AC input power directly from the power
    source. The input range is from 220 VAC to 240 VAC, at 50 or 60 Hz.
    /LV_ENA: Enabling signal from the System Controller Enables the LVPS when
    the System Controller receives a Power On command.
    /FAN_ENA: From System Controller. Enables the +24v standby voltage for the
    projector fans.
    /COVER_ON: Cover interlock signal. Indicates both covers in place. Enables the
    non-standby outputs.
    Outputs:
    + 5.1VDC Main
    + 5.1VDC Standby
    + 6.2VDC
    ± 15VDC
    + 24VDC
    + 80VDC 
    						
    							Chapter 2---System Description
    2-8Model 230 Service Manual
    /LV_OK: When /LV-ENA is enabled, this diagnostic signal indicates to the
    System Controller the status of the non-standby supply (all outputs working or
    not working).
    Operation:
    The main power is filtered via the input filter to prevent radiation from escaping
    back to the power line. From the line filter, AC power is fed into the Low Voltage
    Power Supply module where AC is rectified, filtered, and compensated for power
    factor correction.
    The +5.1V Standby is on whenever AC power is connected to the projector and
    the circuit breaker on the rear panel is in the On position. The +24V standby
    power for the fans turns on when the /FAN_ENA signal is received from the
    System Controller (this turns off in 5-8 minutes if power is not turned on by the
    remote control or a PC). All other voltages supplied by the LVPS are activated
    when power is turned on at the remote or PC. These include +5.1V for digital
    components, +6.2V for CRT filaments, ±15V for analog circuits, and the +80V
    supply which is used by the High Voltage Power Supply, Video Amplifier PCB,
    and the Horizontal/Vertical Deflection PCB.
    Arc Lamp Power Supply (ALPS)
    P71P74
    1
    3
    5 AC
    INPUTLine
    Earth
    Neutral
    P72
    1
    2
    3 To P9 on
    Backplane
    4
    5
    6
    GND
    /LAMP_LIT
    /LAMP_OK
    /LAMP_ENA
    /COVER_ON
    GNDLAMP_OUT
    LAMP_RET
    P73
    LAMP_OK
    GND1
    2 1
    2To Lamp
    Module, J74
    To Lamp
    Module, J74
    Figure 2-4.  Arc Lamp Power Supply, Block Diagram
    Main Functions:
    •  Provides ignition power to turn the Xenon Arc Lamp ON.
    •  Provides steady state power to maintain the lamp ON.
    Inputs:
    The Arc Lamp Power Supply receives AC input power directly from the power
    source. The input range is from 220-240 VAC, at 50 or 60 Hz.
    /LAMP_ENA: From System Controller. Turns on the ALPS.
    /COVER_ON: Cover interlock signal. Indicates both covers are in place.
    /LAMP_OK: Tells the ALPS that the lamp is installed, the temperature is within
    limits, and the lamp cooling blower is working.
    Outputs:
    +140 VDC boost voltage to the Laser Power Supply. 
    						
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