Hughes Jvc 220 Projector Service Manual
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Chapter 2---System Description GRN_BEAM Similar to RED_BEAM BLU_BEAM Similar to RED_BEAM /VA_OK Issued from the VAB to indicate VAB working properly OUTPUT DESCRIPTION RED_VIDEO Red video output. 0 Volt to 1 Volt. GRN_VIDEO Similar to RED_VIDEO BLU_VIDEO Similar to RED_VIDEO RESTORE DC RESTORE control signal. When this signal is asserted, the 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 #1 Red video input from video input card #1 GRN_VIC #1 Similar to RED_VIC #1 BLU_VIC #1 Similar to RED_VIC #1 RED_VIC #2 Similar to RED_VIC #1 GRN_VIC #2 Similar to RED_VIC #1 BLU_VIC #2 Similar to RED_VIC #1 RED_VIC #3 Similar to RED_VIC #1 GRN_VIC #3 Similar to RED_VIC #1 BLU_VIC #3 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 Model 220 Service Manual 2-27
Chapter 2---System Description V_VIC #2 Similar to V_VIC #1 V_VIC #3 Similar to V_VIC #1 /SEL_VIC #1 Input signal from RGB VIC board which is used to select input video source from VIC #1. /SEL_VIC #2 Similar to /SEL_VIC #1 /SEL_VIC #3 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. 2-28 Model 220 Service Manual
Chapter 2---System Description 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_VIDEOGRN_VIDEOBLU_VIDEO BLANKINGG1 SUPPLYG1 BIAS RESTORE ARC_GND BLU_CATHODE8BLU_GRID19BLU_GRID210 BLU_BEAM16 BLU_HEAT-7BLU_HEAT+6 ARC_GND3 GRN _CATHODE8GRN _GRID19GRN _GRID210 GRN_BEAM14 GRN _HEAT-7GRN _HEAT+6 ARC_GND3 RED _CATHODE 8RED _GRID1 9RED _GRID2 10 RED_BEAM 12 RED _HEAT- 7RED _HEAT+ 6 ARC _GND 3 246 23 2112 13 GRN_G215 BLU_G2 1 G2 SUPPLY 11 RED_G2 19 /SWEEP_OK 3 + 8OV7 + 15V5 + 6.2V9 -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 REDCRT To VPB To GRNCRT To VPB To BLUCRT To VPB To HVPS VIDEO AMPLIFIER BOARD Figure 2-11. Video Amplifier PCB, Block Diagram. Model 220 Service Manual 2-29
Chapter 2---System Description 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_VIDEO Video preamp signals. About 0.5 VPP G1_BIAS Brightness control line. 0 to 5 V DC RED_G2 GRN_G2 BLU_G2 Black 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_BEAM Cathode beam current lines. about 1 volt per 100 UA HIGH VOLTAGE POWER SUPPLY 2-30 Model 220 Service Manual
Chapter 2---System Description INPUTS DESCRIPTION G1_SUPPLY Supply for G1 grid of CRTs. About -200 V G2_SUPPLY Supply for G2 (screen) grid of CRTs. About 1200 V RED_FOCUS GRN_FOCUS BLU_FOCUS Focus supply for CRTs. about 7 KV OUTPUTS DESCRIPTION ARC_GND CRT ground (anode supply return line) HORIZONTAL/VERTICAL DEFLECTION BOARD INPUTS DESCRIPTION /SWEEP_OK Deflection detection line. open collector, low = good deflection RASTER TIMING GENERATOR BOARD INPUTS DESCRIPTION BLANKING Blanking signal. logic F type CRTS OUTPUTS DESCRIPTION RED_FOCUS GRN_FOCUS BLU_FOCUS Focus supply of CRTs. about 7 KV. RED_GRID1G RN_GRID1BL U_GRID1 Grid 1 (G1) signal of CRTs. RED_HEAT+ GRN_HEAT+ BLU_HEAT+ Positive side of the heater voltage for CRTs. About 6.2 V. RED_HEAT- GRN_HEAT- BLU_HEAT- Negative side (return line) of the heater voltage for CRTs. Ground level. RED_ CATHODE GRN_ CATHODE BLU_ CATHODE Video output signals of the VAB. about 40 VPP with peak voltage of about 70 V. Model 220 Service Manual 2-31
Chapter 2---System Description RED_GRID2 GRN_GRID2 BLU_GRID2 G2 (screen) supply of CRTs. about 600 to 800 V OUTPUTS DESCRIPTION ARC_GRD Ground of CRTs ( anode supply return line). SYSTEM POWER SUPPLY INPUTS DESCRIPTION +6.2 V +6.2 V supply line (heater voltage). +15 V +15 V supply for use by Video Amplifier Board. -15 V -15 V supply for use by Video Amplifier Board. +80 V +80 V supply for use by Video Amplifier Board. Interlocks and protection: None 2.3.6 System Controller PCB The System Controller Board (SCB) is located in the electronic card cage (Figure 5-1). The Electronics System is controlled by the SCB. The SCB uses digital and analog circuits to direct the operation of image and raster generation circuits and to control the input/output of power supply operation. The SCB sets the operating parameters of the image, such as brightness and contrast. It also produces internal test patterns and generates on-screen display overlays. The SCB sets the timing for the raster generation to adjust phase, geometric corrections, shading corrections, and convergence. The program memory and the memory for all convergence and shading maps are located on the SCB. The following functions are performed or controlled by the System Controller: • Enables control for the Low Voltage Power Supply, Arc Lamp and cooling fans. • Fault monitors the HVPS, LVPS, Arc Lamp, and fans. • Provides interboard communication via the IIC serial bus. • Controls Zoom and Focus of the Projection Lens. • IIC Interface control • Provides Video Overlays • X and Y convergence control 2-32 Model 220 Service Manual
Chapter 2---System Description • Threshold and Sensitivity for shading • I/O control • Two RS-232 serial interface ports • Infrared (IR) remote control interface. Accepts input from front or rear IR detectors. • A 5-wire JTAG interface port for CPU emulation support. • External 3 color system status LEDs. Green indicates normal, yellow is standby and red indicates a fault condition. • External Service Mode switch (see Figure 5-1). Pressing this switch during a power-up sequence brings the system up in a diagnostic mode (for maintenance) rather than a normal operating mode. The SCB I/O diagram (Figure 2-12) and the list of Inputs and Outputs (Table 2-11) provide information for the technician to perform module-level troubleshooting. Model 220 Service Manual 2-33
Chapter 2---System Description P11 B23 B24 B28 B29 B32 B27 B26 B31 B30 Lens Zoom Lens Focus /LV_ENA /FAN_ENA /LAMP_ENA /HV_OK /LV_OK /LAMP_LIT /LAMP_OK P10 B31 B30 A32 A31 A30 A B20-2021-2122-2223-2324-2425-2526-2627-2728-2829-29 +5.1V stby +5.1V +15V-15VGND ODD_FIELD SRC_VALID H_DRIVE_SC V_DRIVE B9 B10 B2 B1 B3 RED_OVER GRN_OVER BLU_OVER B18 B17 B16 P10 Y_RED_CONV Y_GRN_CONV Y_BLU_CONV X_RED_CONV X_GRN_CONV X_BLU_CONV B4 B5 B6 B1 B2 B3 BLU_THRES GRN_THRES RED_THRES BLU_SENS GRN_SENS RED_SENS B8 B9 B10 B11 B12 B13 IIC_DATA IIC_CLK1 IIC_CLK IIC_CLK3 IIC_CLK2 SYSTEM CONTROLLER BOARD TO PROJ LENS FROM LVPS FROM HVPS FROM ALPS FROM RTG FROM LVPS TO VPB TO CDB TO VPB H_F2V Figure 2-12. System Controller Board, Block Diagram. IIC Interface Communications are performed through the IIC bus to the other PCBs in the system.This three wire bus interface consists of clock line, data line and interrupt line. Data transferred over the IIC bus is listed in Table 2-9 (I/O signals). System Controller Board Input/Output This section provides a description of the inputs to and outputs from the SCB. 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 output. Input refers to an input to the SCB, output refers to an output from the SCB. 2-34 Model 220 Service Manual
Chapter 2---System Description Table 2-11. System Controller Board I/O signals VIDEO PROCESSOR BOARD I/O DESCRIPTION IIC_CLK IIC clock line. Clock line for control of synchronous data transfer over\ the IIC bus interface. IIC_DATA IIC data line. Serial line for synchronous data transfer of the followin\ g data between Video Processor Board and SCB board. I=Input, O=Output. I BEAM CURRENT I OK DETECT O RED_CONT O GRN_CONT O BLU_CONT O BRIGHTNESS O RED_G2 O BLU_G2 O GRN_G2 O WHT_BOOST O BLK_BOOST OUTPUTS DESCRIPTION OVERLAY Overlay control signal /IIC_INT IIC interrupt line. 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 BLU_THRES Threshold correction information for blue. Real time data at 0 volt to 1 volt. GRN_THRES Similar to BLU_THRES RED_THRES Similar to BLU_THRES BLU_SENS Sensitivity correction information for BLU. Real time data at O volt to \ 1 volt. GRN_SENS Similar to BLU_SENS RED_SENS Similar to BLU_SENS Model 220 Service Manual 2-35
Chapter 2---System Description RASTER TIMING GENERATOR INPUTS DESCRIPTION SOURCE_ VALID This signal indicates a new source (or valid). A high indicates a vali\ d stable signal and low indicates change in input signal. ODD_FIELD Square wave with 50 % duty cycle which is low during the odd field of an interlace signal. This signal is high for noninterlaced signals. 280_CLK Square wave signal, 50 % duty cycle, 280 times the frequency of horizontal sync. This clock is synchronized to the horizontal sync. H_DRIVE Square wave 50% duty cycle synchronized to selected horiz sync V_DRIVE Square wave negative going pulse synchronized to selected vertical sync with pulse width of about 4 horiz lines H_F2V DC voltage proportional to horiz frequency OUTPUTS DESCRIPTION ISYNC_CLK 5 mHz clock used to generate the internal sync signals 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 Controller and RTG. CONVERGENCE/DEFLECTION BOARD OUTPUTS 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 the SCB and the Convergence/Deflection board. X_RED_ CONV Red X convergence waveform. The amplitude for full scale correction is about 1 VPP. X_GRN_ CONV Grn X convergence waveform. The amplitude for full scale correction is about 1 VPP. X_BLU_ CONV Blu X convergence waveform. The amplitude for full scale correction is about 1 VPP. Y_RED_ CONV Red Y convergence waveform. The amplitude for full scale correction is about 1 VPP. Y_GRN_ CONV Grn Y convergence waveform. The amplitude for full scale correction is about 1 VPP. Y_BLU_ CONV Blu Y convergence waveform. The amplitude for full scale correction is about 1 VPP. 2-36 Model 220 Service Manual