Hughes Model 230 Projector 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.