Hughes Jvc 200 Projector Service Manual
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Chapter 2---System Description 2.3.10 Scan Reversal Board The Scan Reversal Board (SRB) is mounted vertically on the right side of the card cage. The following functions are provided by the SRB: • Reversal of scan in both horizontal and vertical axes • Horizontal width adjustment for each color (R, G &B) • Horizontal current feedback • Scan failure detection for all six main (horizontal and vertical) deflection amplifiers The Scan Reversal Board Input/Output diagram (Figure 2-16) and the list of inputs and outputs (Table 2-15) provide information for the technician to perform module level troubleshooting. Table 2-14 shows the signal states for modes of projector operation. The SRB does not require any IIC bus interface. Table 2-14. Scanning signal states Mode of Operation FRONT/REAR line FLOOR/CEIL line Front and floor projection Low Low Front and ceiling projection Low High Rear and floor projection High Low Rear and ceiling High High Model 200 Service Manual 2-57
Chapter 2---System Description Figure 2-16. Scan Reversal Board, Input/Output Diagram. Scan Reversal Board I /O This section describes the inputs to and outputs from the SRB. The I/O descriptions are arranged by the source/destination of the signal. The assembly communicated with is the primary heading of each group of signals. Those signals are subdivided into inputs and outputs. Input refers to an Input to the Scan Reversal Board. Output refers to an output from the Scan Reversal Board. 2-58 Model 200 Service Manual
Chapter 2---System Description Table 2-15. Scan Reversal Board I/O signals Horizontal / Vertical Deflection Board INPUTS DESCRIPTION H_OUT_ FLYBACK Horizontal output flyback pulse, about 800 VPP H_LOCK+ Horizontal interlock for yoke connectors. This should be about 5 V when closed or 15 V when open. H_RED+ Output of horizontal red centering (also top of the red horiz yoke). About + 5 Vdc. H_GRN+ Output of horizontal green centering (also top of the green horiz yoke). About + 5 Vdc. H_BLU+ Output of horiz. blue centering (also top of the blue horiz yoke). About + 5 Vdc. V_RED+ Output of red vertical amplifier. about 40 VPP V_GRN+ Output of green vertical amplifier. about 40 VPP V_BLU+ Output of blue vertical amplifier. about 40 VPP +15 V +15 volt supply for use by SRB +5 V +5 volt supply for use by SRB -15 V -15 V supply for use by SRB OUTPUTS DESCRIPTION H_LOCK- Horizontal interlock for yoke connectors. It should be 5 V when closed or 0 V when open. V_RED- V_RED_SENS Current feedback of red vertical amplifier V_GRN- V_GRN_SENS Current feedback of green vertical amplifier V_BLU- V_BLU_SENS Current feedback of blue vertical amplifier FRONT/REAR Front or rear projection status line. Front = low and rear = high FLOOR/CEIL Floor or ceiling status line. Floor = low and ceiling = high H_CUR_FDBK Horizontal current feed back, a DC signal proportional to horz. output current DEFL_OK Deflection status line high (about 2 V) = good low = no scan Convergence/Deflection Board INPUTS DESCRIPTION X_RED+ Output of horizontal red convergence amplifier X_GRN+ Output of horizontal green convergence amplifier Model 200 Service Manual 2-59
Chapter 2---System Description X_BLU+ Output of horizontal blue convergence amplifier Y_RED+ Output of vertical red convergence amplifier Y_GRN+ Output of vertical green convergence amplifier Y_BLU+ Output of vertical blue convergence amplifier OUTPUTS DESCRIPTION X_RED- Current feedback of horizontal red convergence amplifier X_GRN- Current feedback of horizontal green convergence amplifier X_BLU- Current feedback of horizontal blue convergence amplifier Y_RED- Current feedback of vertical red convergence amplifier Y_GRN- Current feedback of vertical green convergence amplifier Y_BLU- Red Yoke Connector NAME DESCRIPTION H_RED_YOK+ Top of red horizontal yoke H_RED_YOK- Bottom of red horizontal yoke RED_LOCK+ Interlock for red yoke. 5 V when closed or 15 V when open. RED_LOCK- Interlock for red yoke. 5 V when closed or 0 V when open. V_RED_YOK+ Top of red vertical yoke V_RED_YOK- Bottom of red vertical yoke X_RED_YOK+ Top of red horizontal convergence yoke X_RED_YOK- Bottom of red horizontal convergence yoke Y_RED_YOK+ Top of red vertical convergence yoke Y_RED_YOK- Bottom of red vertical convergence yoke Green Yoke Connector NAME DESCRIPTION H_GRN_YOK+ Top of green horizontal yoke H_GRN_YOK- Bottom of green horizontal yoke GRN_LOCK+ Interlock for green yoke. 5 V when closed or 15 V when open. GRN_LOCK- Interlock for green yoke . 5 V when closed or 0 V when open. Current feedback of vertical blue convergence amplifier 2-60 Model 200 Service Manual
Chapter 2---System Description V_GRN_YOK+ Top of green vertical yoke V_GRN_YOK- Bottom of green vertical yoke X_GRN_YOK+ Top of green horizontal convergence yoke X_GRN_YOK- Bottom of green horizontal convergence yoke Y_GRN_YOK+ Top of green vertical convergence yoke Y_GRN_YOK- Bottom of green vertical convergence yoke- Blue Yoke Connector NAME DESCRIPTION H_BLU_YOK+ Top of blue horizontal yoke H_BLU_YOK- Bottom of blue horizontal yoke BLU_LOCK+ Interlock for blue yoke. 5 V when closed or 15 V when open. BLU_LOCK- Interlock for blue yoke . 5 V when closed or 0 V when open. V_BLU_YOK+ Top of blue vertical yoke V_BLU_YOK- Bottom of blue vertical yoke X_BLU_YOK+ Top of blue horizontal convergence yoke X_BLU_YOK- Bottom of blue horizontal convergence yoke Y_BLU_YOK+ Top of blue vertical convergence yoke Y_BLU_YOK- Bottom of blue vertical convergence yoke- Model 200 Service Manual 2-61
Chapter 2---System Description 2.3.11 Backplane PCB The Backplane PCB is the interface that connects the Power Supplies, VICs, PCBs, and other components together, either through a direct connection to a connector on the Backplane or through cables to connectors on the Backplane PCB. Signals are not modified in any way by the Backplane. It serves only as an interconnecting point. Refer to Figure 2-17 for a general idea of how the projector wiring is interconnected through the Backplane PCB. Backplane PCB P8 P12 P14 P18 P9 P7 P72ALPS HVPSP43 P4P32 CDBP3P31 P10 P11 SCB P13RTG P16 P17 VPB P1P67 VAB P2P68 P6P36 HVDB P5P35 P19Proj LensP62 Fans P76LVPS VIC #1 VIC #2 VIC 3# Figure 2-17. Backplane Board Interface Block Diagram. 2-62 Model 200 Service Manual
Chapter 2---System Description 2.4 Image Light Amplifier Technology Section 2.2 explained how the various units, including the ILA® assemblies, in the Optical System work together to produce the image on the screen. This section focuses mainly on how the ILA® assembly itself works. An Image Light Amplifier (ILA®) assembly (Figure 2-18) is a device that uses low-intensity images to modulate a high-intensity light through a liquid crystal layer. It is the key component in producing very bright, high resolution images from Hughes-JVC large-screen projectors. Figure 2-18. The Hughes-JVC Image Light Amplifier®. Optically, there are two sides to an ILA® assembly with a light blocking layer in the center. On the input side there is a photo- conductive layer where the image from a CRT is focused through a relay lens. This image is electrostatically coupled through the light-blocking layer and mirror to a liquid crystal layer on the output \ side of the ILA® assembly. Model 200 Service Manual 2-63
Chapter 2---System Description High intensity light from a Xenon Arc Lamp is applied, through a prism (where it is polarized), to the output side of the ILA® assembly where the liquid crystal layer is located. The polarized light passing through the liquid crystal is modulated (changing the polarity of the light waves), in accordance with whatever image is on the input side of the ILA® assembly. The axis of the polarized light is proportional to the brightness on the input side of the ILA® assembly. When the photoconductor on the input side is not illuminated, the liquid crystal does not rotate the polarized light from the Arc Lamp. No light passes through the prism and the screen is dark. When the input side is fully illuminated, the liquid crystal rotates the polarized light 90° from \ a horizontal direction to a vertical direction. Ninety nine percent (99%) of the light entering the ILA® assembly is reflected and passes through the prism resulting in a white screen. The modulated high-intensity light is reflected back out of the output side of the ILA® assembly, through the Prism and the Projection Lens and onto the screen. (see Figure 2-19). Figure 2-19. Simplified image/optical path. 2-64 Model 200 Service Manual
Chapter 2---System Description Model 200 Service Manual 2-65
Chapter 3---Service Adjustments 3.0 Service Adjustments Contents 3.1 Arc Lamp Focus and Alignment...............................................................3-1 3.2 Arc Lamp Current Setting........................................................................\ 3-4 3.3 Electronic Module Tilt-up........................................................................\ .3-5 3.4 ILA® Back Focus........................................................................\ .............3-5 3.5 CRT Mechanical Focus........................................................................\ ....3-7 3.6 CRT Rotation........................................................................\ ...................3-9 3.7 CRT Electronic Focus........................................................................\ ......3-10 3.8 ILA® Overlap........................................................................\ ....................3-10 3.9 Jumper Settings........................................................................\ ...............3-11 3.9.1 Front/Rear Jumper Settings..........................................................3-11 3.9.2 Inverted Vertical Jumper Settings..................................................3-12 3.10 Vertical and Horizontal Size Settings.......................................................3-12 3.11 Software Updating........................................................................\ ...........3-14 3.12 Cleaning Lens, ILA® assemblies, and Mirrors.........................................3-16 This chapter details adjustment procedures required to maintain the Mode\ l 200. Refer to Figures 4-1 and 4-11 to locate assemblies and components. For \ a complete list of tools required to perform adjustments, refer to Chapter\ 1. CAUTION! Before performing procedures in this chapter, review the chapter on Safety at the beginning of this manual. WARNING!!! When performing procedures in this chapter that require the projector covers to be removed, wear high volta\ ge gloves (ANSI/ASTM 10,000 volt rated) when working near the CRTs, Arc Lamp, or\ power supplies. Wear safety goggles (rated X5) when working anywhere near the light path from the arc lamp or the projection lens. 3.1 Arc Lamp Focus and Alignment The Arc Lamp must be refocused and the XY axes realigned whenever an Arc Lamp is replaced. The Arc Lamp can also become defocused or misaligned from physical shock to the projector. 1. Select and view Red, Green, and Blue. 2. Select Test Pattern 4, Flat Field. Model 200 Service Manual 3-1