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JVC 370 SC, 330, 340 SC service manual Video Signal, Failure Detection

Models: 340 SC 370 SC 330

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Video Signal

Chapter 2—Functional Description

Circuit failure detection.

Beam current sense.

Arc protection.

This section uses Figure 2-16 for reference. The description provides information to perform module-level troubleshooting.

Figure 2-16Video Amplifier Board, Block Diagram

Video Signal

The video signal comes directly from the VPB backplane connector via a coaxial cable to the Video Amplifier Board and enters as VIN. The input signal will be a maximum of 1Vpp. The video amplifier takes the input signal, amplifies and level shifts it so that it will be a negative-going 75Vpp signal modulating the +84Vdc black level, and applies this to the cathode of the CRT. In general, the 84Vdc black level will be seen only during the DC Restore interval. Power for the video amplifier is a locally derived 100V that is regulated down from the 107V input from the SPS.

Failure Detection

The Failure Detection circuit senses the health of the video amp's 100V power supply. When the 100V supply falls below about +64V, the normally low /VIDOK signal is pulled high. The /VIDOK signal is then sent to the VPB.

Model 330, 340SC and 370SC Service Manual

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JVC 370 SC, 330, 340 SC service manual Video Signal, Failure Detection

Contents

Model Model 340 SC Model 370 SC DECLARATION OF CONFORMITYHughes-JVC Technology Corporation SERVICE MANUALConfidential and proprietary information Manufacturer Hughes-JVC Technology CorporationWarnings and Cautions Safety InformationSafety Equipment IntroductionProjector Weight Installation SafeguardsUltra Violet and Infrared Light Heat SafeguardsLight Safeguards FansUltraviolet radiation, dangerous glare, and high internal gas pressure Power Fluid SafeguardsPower Supply Ventilation and Foreign Object RetrievalModel 330, 340SC, and 370SC Service Manual SafetyModel 330, 340SC, and 370SC Service Manual Safety1.1 Acronyms Used In Manual 1.0 IntroductionModel 330, 340SC and 370SC Service Manual 1.2 Safety1.3 Updates 1.4 Hardware CompatibilityVideo Amplifier Board 2.0 Functional Descriptions Contents2.1 Cover and Base 2.3 Electronics Systems Overview 2.2 External Power RequirementsThe Model 330, 340SC and 370SC Electronics System consists of System Power Supply 2.4 System PowerFigure 2-2 Backplane Status Indicators ∇ Model 330. Model 340SC = +25V/80a Model 370SC = +30V/100a 2. +24V Standby and Arc Lamp power supplies turn on Arc Lamp Ignitor 22-30V depending on projector model High Voltage Power Supply Pins 1,4,5,10 not used High Voltage Power SupplyPower and Control Connector Model 330, 340SC, and 370SC Service ManualCRT anode voltages are not user controllable. They are fixed at 32KV with a maximum output of 2.1mA total or 0.7mA per CRT. The anode voltage is the primary acceleration voltage for the CRT. Other bias voltages screen grid, G2, and control grid, G1 are used to control the level of beam current. The anode voltage is routed out of the top of the HVPS, into the CRT housing to three 3 bulkhead connectors. From there, the anode wires on the CRTs route the anode voltage directly to the CRT. The anode voltages are overvoltage and overcurrent protected in the event of short circuits or CRT arcing 2.5 Card Cage 370SC 2.6 Circuit BoardsDescription 340SCChapter 2-Functional Descriptions Model 330, 340SC, and 370SC Service Manual2-16 2-17 Figure 2-10 Raster Generation Block DiagramModel 330, 340SC and 370SC Service Manual Chapter 2-Functional DescriptionRaster Timing Generator Board RTG p/n Sync Detector and Selector Sync GeneratorSerration and Equalization Lockout Phase Locked LoopVSYNC Detector, Field Separator, and Mux Adjustment Counters Information Serial CommunicationDescription IICCLK Raster Timing Generator I/OHorizontal Deflection Board Inputs Interlocks and ProtectionHorizontal Deflection Board P/N 102523 HDB System Power SupplyVertical Oscillator Horizontal Power Supply Horizontal Phase Locked LoopHorizontal Centering Geometric Correction Flyback SwitchingOutput Section Description Horizontal Sweep Failure DetectionSerial Communication InformationHorizontal Deflection Board I/O Raster Timing Generator Inputs Vertical Deflection Board P/N 102521VDBSystem Power Supply Interlocks and ProtectionVertical raster centering Top and bottom pincushion correction Vertical Preamps Sweep Failure Detection Vertical AmplifiersSide Pincushion and Keystone Correction Top and Bottom Pincushion and Keystone Correction Horizontal Linearity CorrectionSerial Communication Correction AmplifiersRXCORR RYCORR GXCORR GYCORR BXCORR System Controller Board General I/OInformation DescriptionSystem Controller Board Outputs Internal Interlocks and ShutdownsInput OutputChapter 2-Functional Descriptions Model 330, 340SC and 370SC Service Manual2-42 Video Processor Board P/N 104672 VPB Decoder B, G, and R Brightness and Contrast Amplifiers Video/Sync MuxV & H Sync Strip SG Sync StripSwitch Logic and Video Enable On-Screen SwitchGamma Correction RGB Sensitivity and Threshold Amplifier Information ILA BiasDynamic Focus Amplifier Serial CommunicationDescription General I/OSystem Controller Board InputRaster Timing Generator System Controller BoardOutputs DescriptionVertical Deflection Board Decoder Image Light AmplifiersOutputs DescriptionOutputs High Voltage Power SupplySystem Power Supply Interlocks and ProtectionOutput Video Amplifier Board P/N 103567 or 103774 VABInternal Failure Detection Video SignalArc Protection DC RestoreEnable Circuit Beam Current SenseGeneral I/O This section provides a comprehensive description of the inputs to and outputs from the VAB. The I/O description are arranged by the source/destination of the signal and so the assemblies communicated with are used as the primary heading of each group of signals and then are further subdivided into inputs and outputs. In each case, the signals direction is noted, with input referring to an input to the VAB, and output to an output from the VAB e.g. under Video Processor Board Input CLAMP refers to the signal CLAMP that is an input to the VAB from the Video Processor Board. When test points are provided for the I/O they are notedVideo Processor Board Description System Controller Board P/N 104668 SCBSystem Power Supply InputsGeneral Functional Description Page Expanded Memory Working and Compressed MemoryDACs Correction Address GeneratorOverlay Address Generator Overlay MemoryIR Interface Overlay InterfaceLED Display Buffers and Logic RS232 InterfaceGeneral I/O IIC InterfaceSerial Interface There are three 3 ports for receiving IR radiation. One 1 is located on the front of the projector just above the Green projection lens and the other two 2 are located on the rear panel. One of the receivers on the rear panel is located next to the LED display and, like the front receiver, is used for directly receiving IR radiation. The other rear-mounted receiver is used for connecting an IR repeater, which is an optional device that allows the user to control the projector from up to 150 feet awayDescription Video Processor BoardDescription InputDescription Raster Timing GeneratorDescription InputDescription Vertical Deflection BoardDescription InputHorizontal Deflection Board Backplane Board p/n BackplaneRelay Lens CRT AssemblyImage Light Amplifier ILA Assembly 2.7 Optical Sectionlight. The vertically polarized light then passes through the prism to the projector lens. The ILA assembly combines the input signal from the CRT with the high intensity light from the arc lamp. Thus, the brightness of the screen image does not depend on the brightness of the CRT but on the light from the xenon arc lamp. A more detailed explanation of the ILA assembly is in Section 2.8 at the end of this chapter Screen CRT ImageCombined Image and High Intensity Light=Bright ImagePrism Arc Lamp AssemblyProjection Lens Optical Subassemblies 2.8 Image Light AmplifierFigure 2-20 The Hughes-JVC Image Light Amplifier Figure 2-21 Simplified illustration of the Series 300 Projector optical path Chapter 3---Service Adjustments 3.0 Service Adjustments3.1 Service Cover-Off Power-On Sequence ContentsMain AC Circuit Breaker 3.2 CRT Yoke Rotation 7. View R 3.3 Vertical Size Tracking 3.4 Vertical Linearity Tracking 3.5 Horizontal Size Tracking Note On Super Contrast Ila Assemblies 3.6 ILA Bias Settings3.7 CRT Mechanical Focus The lower-left rod adjusts the CRT to ILA distance z- axis 2. Increase Size to 100% horizontal and vertical 3.8 Electronic Focus Front/Rear Jumpers 3.9 Jumper SettingsF R O N T p ro jectio n R E A R p ro jectio nJ601 Inverted Vertical JumpersJ300 J301 J500 J501 J200 J201 J600 J400G2 Setting 3.10 G2 AdjustmentSensitivity/Threshold Offset To set G2 1. Cut off R and B and view G Model 330 Arc Lamp Alignment and Focus 3.11 Arc Lamp Alignment and FocusTo refocus the Model 330 Arc Lamp Y-Axis Plate Model 340SC and 370SC Arc Lamp Alignment and FocusX-Axis Plate Z-Axis Screwplate Figure 3-9. Model 340SC and 370SC Arc Lamp Adjustments 3.12 Arc Lamp Current Adjustment2. Measure the number of millivolts between pins 3 and 4 on SPS J505 Model 330, 340SC, 370SC Service Manual Chapter 3---Service Adjustments3-23 Model 330, 340SC, and 370SC Service Manual 4.0 Maintenance Remove/Replace4.1 Introduction Contentsbefore performing any removal and replacement procedures WARNING!!! Disconnect AC power from the projectorModel 330, 340SC, and 370SC Service Manual Chapter 4-MaintenanceFigure 4-1 Major components of the Model 330 Projector Model 330. 340SC, 370SC Service Manual Chapter 4-MaintenanceFigure 4-2 Major components of the Model 340SC and 370SC Projectors 4.3 Ventilation Filters 4.2 Projector CoversModel 330 Ignitor and Arc Lamp Assembly P/N 900611S Removal 4.4 Arc Lamp AssemblyJ503 and J504 Ignitor Assembly Location on Wire ColorWire goes to IgnitorJ503 J504 J505 Interlock Switch Lamp Current Adjust Interlock Switch Fan Connector Circuit BreakerStart Capacitor Squirrel Cage Fan Cable 3-mm Set Screw Mounting Screws Collimating Condensing Lens Adjustment4.5 System Power Supply screws under lip AC Power Terminal Block Ground Main AC Circuit Breaker Mounting4.6 Electronics Module 11. Replace the module in the reverse order Model 330 CRT Removal 4.7 Cathode Ray Tube CRT5. Remove the video amplifier board from the CRT Assembly Section Model 330, 340SC, and 370SC Service Manual Figure 4-10 Model 340SC and 370SC CRT AssemblyFigure 4-11 CRT Z-Axis Focus Adjustment Rods circled Chapter 4-MaintenanceModel 340SC and 370SC CRT Removal 4.8 Video Amplifier Board VABTo remove a VAB see Figure 4-9 or Figure To remove the CRT yoke see Figure 4-9 or Figure 4.9 CRT Yoke4.10 High Voltage Power Supply HVPS 4.11 Card Cage Printed Circuit Boards 4.12 Image Light Amplifier Assembly Lens Locking Rods 4.13 Projection Lens4-24 Chapter 4-MaintenanceModel 330. 340SC, 370SC Service Manual Table 4-2 for reference to part numbers, if necessaryLens Part Number or Designation 4.14 SCB Socket Battery ReplacementCAUTION! Never place the socket battery on a metal Lens ThrowCAUTION! Never place the socket battery on 340SC 4.15 Recommended SparesDescription Quantity5.1 General Information 5.0 TroubleshootingContents Page 5.2 Power-On Codes Code Second SetDescription Description 5.3 Break PointsCode MeaningDescription Resetting the ProjectorBreak Trap Data from the Diagnostics Menu CodeModel 330, 340SC, and 370SC Service Manual 5.4 Main Menu StructureVersion 5.1.0 Software Menu Diagram Chapter 5---TroubleshootingSymptom to Problem andPossible Solution ServiceSymptom to Problem andPossible Solution ServiceSymptom to Problem andPossible Solution ServiceSymptom to Problem andPossible Solution ServiceSymptom to Problem andPossible Solution ServiceSymptom to Problem andPossible Solution ServiceIntermittent Glossary of Terms Cold Mirror Test pattern of black-to-white gradation bars. The more levels Intensity Lumen Retrace Phase adjustmentResolution RasterScan See Arc Lamp temporarily with the Executive I/R remoteGlossary Model 330, 340SC, and 370SC Service Manual