JVC 340 SC, 370 SC, 330 User Manual

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SERVICE

MANUAL

Model 330 Model 340 SC Model 370 SC

Hughes-JVC Technology Corporation

2310 Camino Vida Roble, Carlsbad, CA 92009-1504

☎

760-929-5300

DECLARATION OF CONFORMITY

760-929-5410

service@hjt.com

✉

PER ISO/IEC GUIDE 22 AND EN 45014

Manufacturer: Hughes-JVC Technology Corporation

2310 Camino Vida Roble Carlsbad, CA 92009-1504 USA

Hughes-JVC declares that this product conforms to the following Product Specifications (Directive/Standard):

Safety: EN 60950

IEC 950 (1992)

EMC: EN 55022 (1988) / CISPR-22 (1986) Class "A"

EN 50082-1 (1992) / IEC 801-2 (1991) EN 50082-1 (1992) / IEC 801-3 (1984) EN 50082-1 (1992) / IEC 801-4 (1988) ANSI C63.4-1992, FCC, Part 15, Class A

In addition, the above product complies with the requirements of the Low Voltage Directive 73/23 EEC and the EMC Directive 89/336/EEC.

105662 First Edition January 1998 Rev A September 1998

Hughes-JVC Technology Corporation is ISO 9001 Registered and Certified.

Confidential and proprietary information.

This manual was produced by Hughes-JVC Technology Corporation and may be revised without prior notice.

No part of this manual may be reproduced in any form without the express written permission of Hughes-JVC Technology Corporation.

is a registered trademark of Hughes-JVC Technology Corporation.

ILA

iii

Model 330, 340SC and 370SC Service Manual

Safety Information

Introduction

Before operating or working on a Model 330, 340SC and 370SC Projector, especially with the cover off, please read this safety information section thoroughly. Procedures requiring the opening of the projector covers and/or contact with electrical components should be performed by qualified service personnel. Strictly adhere to all notes and warnings.

Safety Equipment

Safety equipment specified in the Hughes-JVC Series 300 Projector Service and Operator’s Training Course and certification program or equivalent should be used for maintenance of the equipment.

Safety

Warnings and Cautions

Warnings and Cautions in this manual should be read thoroughly and strictly adhered to. Warning and Caution symbols and definitions are as follows:

WARNING!!!

and/or specific procedure or situation that could result in personal injury if improperly performed.

CAUTION!

hazards that could cause severe eye injury or a specific procedure or situation that could result in damage to the equipment if improperly used.

The following important safety instructions are designed to insure your safety and the long life of your projector. Be sure to read these safety instructions thoroughly and adhere to all warnings given below.

Warns user of a potential safety hazard or potential light

Warns user of a potential electric shock hazard

This device complies with Part 15 of the FCC Rules. Operation is subject to the following two conditions: (1) this device may not cause harmful interference and (2) this device

Model 330, 340SC, and 370SC Service Manual v

Safety

must accept any interference received including interference that may cause undesired operation.

Operation of this equipment in a residential area is likely to cause harmful interference, in which case the user will be required to correct the interference at their own expense.

Shielded interconnect cables must be used with this equipment to insure compliance with the pertinent RF emission limits governing this device.

Installation Safeguards

WARNING!!!

power on the projector until the damaged cable is replaced.

not

CAUTION!

If there is any visible damage to any of the cables

Place the projector on a smooth, stable and level surface

in an area free from dust and moisture. Do not place the equipment in direct sunlight or near heat-radiating appliances. Smoke, steam and exposure to direct sunlight could adversely affect the internal components. Avoid rough handling when moving your equipment, as a strong shock could damage its internal components.

CAUTION!

If installing a ceiling mount, use only parts supplied or recommended by the manufacturer. Observe all instructions and warnings as listed in this manual.

Projector Weight

The HJT projector and shipping container have a combined weight of either 512 (Model 330 and 340SC) or 550 (Model 370SC) pounds. The HJT shipping container weighs 170 pounds and the projector itself weighs either 342 (Model 330 and 340SC) or 380 (Model 370SC) pounds.

Do Not Tilt the Projector More Than 85 Degrees Do not mount the projector on an excessively tilted base. The projector can be tilted a

maximum of 85 degrees. Mount it only on a stable, vibration-resistant base capable of supporting at least three times its weight. If in doubt, contact the factory.

Model 330, 340SC, and 370SC Service Manual

Safety

Avoid Projector Angles of 15° to 23° Due to voids in the prism fluid there is a dead zone of 19° ± 4°. For this reason, avoid

projector angles of 15° to 23°. Maximum Projector to Screen Angle is 15°

The maximum vertical tilt angle from projector to screen is 15°. This is the maximum amount of keystone correction that is possible.

Heat Safeguards

Fans

The projector has multiple fans (exact number varies with projector model number) to cool the projector system. Do not block the intake or outflow of any of the fans. Intense heat is emitted within the system and must be properly dissipated in order to keep the system running properly.

CAUTION!

ports can lead to projector overheating. Do not enclose the unit in a restricted space. Refer to the appropriate thermal clearance and for specific clearances needed for heat dissipation. Allow at least ten (10) minutes for projector cool down before removing power.

has stopped running. This fan protects the arc lamp from overheating.

CAUTION!

Light Safeguards

Ultra Violet and Infrared Li ght

Eye/face protection is required from ultra violet light and infrared light in accordance with the following conditions:

1. X3 (up to 375 nanometers) shade goggles must be worn by anyone near the projector when the lamp is lit and the cover is off.

2. X5 (375 to 700 nanometers) shade goggles when actually working on the projector near the arc lamp source.

Do Not Block Ventilation. Blocking air intake or exhaust

Operator’s Manual

Do not unplug the power cord until after the arc lamp fan

for physical access and

vii

Model 330, 340SC, and 370SC Service Manual

Safety

WARNING!!!

High temperature, ultraviolet and infrared light. Refer

all service to factory authorized personnel.

Ultraviolet radiation, dangerous glare, and high internal gas pressure is present at the Xenon Arc Lamp. It is contained in a protective reflector housing module.

DO NOT operate the Xenon Arc Lamp outside its intended standard housing or outside of the projector.

When replacement is required, the arc lamp must be replaced as an entire module as outlined in the Hughes-JVC Model 330, 340SC and 370SC Projector Service Manual.

No attempt should ever be made to replace the arc lamp inside its module! The arc lamp produces dangerous intense light with hazardous levels of ultraviolet and

infrared radiation. It operates at high temperatures (180ºC, maximum 300º C or over 500º F).

Do not touch the xenon arc lamp or any connections when the lamp is ignited or is arcing.

WARNING!!! BRIGHT LIGHT!

Never look directly at the Arc Lamp, the lighted Projection Lens, or into the lamp housing, from any distance, when the projector is ON and light is projected. Direct exposure to light of this brightness can cause severe eye injury.

viii

WARNING!!!

High voltage access and safety interlock. Defeat

restricted to factory authorized service personnel!

WARNING!!!

Allow at least one minute to bleed off high voltage even after the unit has been turned off.

High voltage points up to 40,000 volts are exposed inside the covers.

Due to high voltage danger, DO NOT TOUCH:

White cables to CRTs—these cables can cause severe shock from a tiny, invisible crack or hole and should never be touched while projector power is on.

CRT anodes—underneath the CRTs.

Main power +/- supply posts—if shorted with metal objects,

80 amps can flow across the terminals.

Model 330, 340SC, and 370SC Service Manual

Safety

CRT yoke assemblies and other proximity electrical assemblies, components and wiring—if performing the yoke rotation or width adjustment (outlined in Section

3.2), always use an

ANSI/ASTM 10,000 volt rated safety glove.

Periodically check the condition of safety gloves for cracks.

Arc Lamp main power ± posts.

Power Supply

The projectors operate from power sources indicated in the table below. Verify that local power source matches these requirements before operation!

Projector Power Supplies

Power

AC Current Hz Watts

330

200-240V

50-60

2,700

340SC

200-240V

20 50-60 3,325

370SC

200-240V

30 50-60 4,550

Handle the power cord carefully and avoid excessive bending. A damaged cord may cause electric shock or fire. For continued safe and reliable operation, only use cables supplied by the manufacturer for power and signal connections.

Installation should be performed by an electrician with current knowledge of electrical codes in the country of use.

Fluid Safeguards

Certain components of the projector contain fluid. If any fluid from the projector contacts the skin, wash off with soap and water. If any fluid from the projector splashes into the eyes, rinse with cool running water.

Ventilation and Foreign Object Retrieval

Ensure the projector’s multiple fans are free from obstructions and operating properly. Air filters are located at vent ports on the cover. Air filters require periodic cleaning to ensure adequate cooling of the projector (see Section 4.3). Verify that vent ports are clear of all obstructions.

Keep the projector free from foreign objects, such as hairpins, nails, paper, etc. Do not attempt to retrieve such objects yourself or insert metal objects such as wire and screwdrivers inside the unit. If an object falls inside the projector, unplug the projector immediately and call a Hughes-JVC certified technician for removal.

Model 330, 340SC, and 370SC Service Manual

Safety

WARNING!!!

Various procedures in this manual involve the removal and replacement of system subassemblies. Ensure that the projector AC power plug is removed from the AC outlet

to attempting any of these procedures.

prior

Model 330, 340SC, and 370SC Service Manual

Safety

Model 330, 340SC, and 370SC Service Manual

1.0 Introduction

This Model 330, 340SC and 370SC Service Manual combines three (3) similar projector models into one (1) reference book, and should be used in conjunction with the appropriate projector Operator’s Manual. This manual provides more detailed information on troubleshooting and maintaining the projectors and a more in-depth functional description of the system subassemblies than the specific Operator’s Manual, which cover the specific projector system description, installation, adjustments, operation, maintenance, specifications, troubleshooting guide, and parts list.

The areas covered in this Service Manual include any similarities and differences of functional descriptions of Model 330, 340SC and 370SC projector electronics, service adjustments, maintenance (removal and replacement of subassemblies), and troubleshooting.

Chapter 1---Introduction

1.1 Acronyms Used In Manual

ALPS Arc Lamp Power Supply CH Channel CPU Central Processing Unit CRT Cathode Ray Tube DSP Digital Signal Processor EPROM Erasable Programmable Read-Only Memory F to V Frequency to Voltage G2 CRT Grid 2 HDB Horizontal Deflection Board HDTV High Definition Television HSYNC Horizontal Sync HVPS High Voltage Power Supply ILA® Image Light Amplifier I/O Input/Output I/R Infrared kHz Kilohertz LED Light Emitting Diode LVPS Low Voltage Power Supply NTSC National Television Standards Committee PCB Printed Circuit Board PLL Phase Lock Loop PLUGE Picture Line-Up Generating Equipment RAM Random Access Memory RGB Red, Green and Blue ROM Read Only Memory

Model 330, 340SC and 370SC Service Manual 1-1

Chapter 1---Introduction

RTG Raster Timing Generator SCB System Control Board SPS System Power Supply TTL Transistor-Transistor Logic VAB Video Amplifier Board VCO Voltage Controlled Oscillator VDB Vertical Deflection Board VIN Video Input VPB Video Processor PCB VSYNC Vertical Sync VTR Video Tape Recorder

1.2 Safety

High voltages and high intensity light sources exist in the Model 330, 340SC and 370SC Projector Systems and power supplies. Prior to performing any procedures, adjustments or maintenance review the chapter on Safety Information at the front of this manual.

1.3 Updates

This manual will be updated with information provided by Service Bulletins and manual supplements whenever necessary.

1.4 Hardware Compatibility

The table below lists part numbers currently compatible between the Model 330, 340SC and 370SC projectors, and those parts that are different in each.

Table 1-1

Printed Circuit Boards

DIFFERENT

Lamp Assembly Ignitor System Power Supply High Voltage Power Supply

SAME

Hardware Compatibility

330

900611S

102083 104070 100562

340SC

PART NUMBERS

104651 102207 104071 100562

370SC

104120 104475 104038 103769

1-2

Raster Timing Generator Horizontal Deflection Board Vertical Deflection Board Video Processing Board

100568 102523 102521 104672

Model 330, 340SC and 370SC Service Manual

100568 102523 102521 104672

Chapter 1---Introduction

Printed Circuit Boards

Video Amplifier Board System Controller Board

Table 1-2

Different

3,000 lumens 2,500 ANSI lumens

220V AC, 20A, 60Hz 2,700 Watts power

1,500 W Xenon arc lamp 2,000 W Xenon arc lamp 3,000 W Xenon arc lamp

Same

5.2.1 software graphics enhancement

Projector Model Comparisons

330 Model

4,200 lumens 3,700 ANSI lumens

220V AC, 20A, 60Hz 3,325 Watts power

5.2.1 software graphics enhancement

340SC Model

330

103774 104668

340SC

103774 104668

6,800 lumens 6,000 ANSI lumens

220V AC, 30A, 60Hz 4,550 Watts power

5.2.1 software graphics enhancement

370SC

103774 104668

370SC Model

30 memories decoder board option

Model 330, 340SC and 370SC Service Manual 1-3

Chapter 2—Functional Descriptions

2.0 Functional Descriptions

Contents

2.1 Cover and Base............................................................................................2–2

2.2 External Power Requirements.....................................................................2–3

2.3 Electronics Systems Overview....................................................................2–3

2.4 System Power..............................................................................................2–5

System Power Supply................................................................................2–5

Arc Lamp Ignitor.......................................................................................2–9

High Voltage Power Supply......................................................................2-11

2.5 Card Cage....................................................................................................2-14

2.6 Circuit Boards .............................................................................................2-15

Raster Timing Generator Board (RTG) p/n 100568 ................................2-18

Horizontal Deflection Board P/N 102523 (HDB).....................................2-25

Vertical Deflection Board P/N 102521(VDB)..........................................2-32

Video Processor Board P/N 104672 (VPB)..............................................2-43

Video Amplifier Board P/N 103567 or 103774 (VAB)............................2-54

System Controller Board P/N 104668 (SCB)............................................2-59

Backplane Board p/n 100571...................................................................2-71

2.7 Optical Section............................................................................................2-72

CRT Assembly..........................................................................................2-72

Arc Lamp Assembly..................................................................................2-75

Optical Subassemblies...............................................................................2-76

2.8 Image Light Amplifier.................................................................................2-76

This chapter provides functional descriptions of the major assemblies in the Model 330, 340SC and 370SC projectors.

Emphasis is placed on a description of system components to the functional block level. A number of block diagrams are provided for user reference.

Figure 2-1 provides a block diagram overview of the HJT Model 330, 340SC and 370SC projectors. For simplicity, each major electronics assembly is shown with signal paths between appropriate functional units. Major physical and electronics assemblies will be described in more detail in the following sections of this chapter.

Model 330, 340SC and 370SC Service Manual 2–1

Chapter 2—Functional Descriptions

Low Voltage Power Supply

Lamp Ignitor

System Controller

Line Voltag e

RS 232

Infrared Remote

System Power Supply

Arc Lamp

Horizontal Deflection

Channel 1 Channel 2

(R,G,B, H/V Sync)

Video Processor

Figure 2-1

Model 330, 340SC and 370SC System Block Diagrams

2.1 Cover and Base

and 370SC projectors must be installed for proper operation. Operation of the projector, other than for maintenance, with the covers removed is not recommended and will void the projector warranty.

CAUTION!

Video Output Amplifier

Raster Timing Generator

The covers for the HJT Model 330, 340SC

Vertical

Deflection

and

Convergence

High Voltage Power Supply

Fans

Image Light Amplifiers (3 each

CRTs (3 each)

In addition to aesthetics, the covers on the Model 330, 340SC and 370SC projectors serve several functions. The covers are an integral part of the cooling system of the projector. Air intake filters are contained in the covers as are cooling fans. The covers provide the operator and audience with protection from the extremely bright light produced in the projector. The covers also serve to reduce the noise generated by operation of the projector. The UL approval is only valid with the covers installed since they provide the primary protection to prevent personnel from coming into contact with the high voltages and currents contained within the projector.

2–2 Model 330, 340SC, and 370SC Service Manual

The HJT Model 330, 340SC and 370SC

WARNING!!!

projectors use high voltages and high currents. Operation with covers removed exposes personnel to these dangerous conditions and may result in serious injury or death. No user-serviceable parts are contained within the projector. Refer all maintenance to only factory authorized and trained technicians.

The projector cover is a two-piece molded assembly. It is fastened to the projector frame by six (6) screws: two (2) on the rear cover; and four (4) on the front cover.

The fan intake side of the cover (right side) has filters on the intake vents. Periodic cleaning of the filters is required and should be performed in accordance with the procedure in this manual (Section 4.3). To avoid overheating the projector, ensure that the cover vent ports are free of obstructions at all times and that an adequate supply of fresh air is provided to the projector during operation.

2.2 External Power Requirements

Chapter 2—Functional Descriptions

The projectors require 208V to 240V, 50 Hz to 60 Hz, single-phase AC power. The units are equipped with an attached AC power cord and 3-prong twist lock plug (Model 330 and 340SC use Hubble Model 2323; Model 370SC uses Hubble Model 2623 or equivalent).

CAUTION!

Operation at voltages and frequencies outside of these

listed parameters may cause damage to the projector and will void the warranty.

2.3 Electronics Systems Overview

The objective of this portion is to provide a good general understanding of the projector electronics. The understanding gained will enable service personnel to more effectively maintain the projector to produce the desired result—a great picture on the screen —and quality you can see.

The Electronics Systems portion of this manual is based on block diagrams. The diagrams used have been drawn with two purposes in mind. First, they are general enough to be able to gain an understanding of the overall function of the various components of the system. Second, the block diagrams contain enough detail to make them valuable as a troubleshooting tool should the need arise. Schematics are not used but, where necessary, simplified circuitry is shown to aid in understanding the capabilities and/or limitations of the system. Discussion of troubleshooting is included but is largely confined to symptoms and identification of failed assemblies.

The Hughes-JVC Model 330, 340SC and 370SC projectors are multi-sync projectors capable of data, graphics, and display from 15KHz to 90KHz

Model 330, 340SC and 370SC Service Manual 2–3

Chapter 2—Functional Descriptions

horizontal and 45Hz to 120Hz vertical. The projected image is continuously variable from 6 ft to 60 ft over throw distances (varies by projector model) from 10 ft to over 360 ft. All HJT Series 300 projectors are capable of keystone, pincushion, and linearity correction. The projectors feature digital control of functions, including convergence, picture adjustments, switching and diagnostics. In addition, the projector provides the ability to control the relative brightness anywhere on the screen.

The capabilities of the Model 330, 340SC and 370SC projectors are provided by a sophisticated electronics system, which consists of power supplies, input/output devices, and various circuit boards, and using both analog and digital components to provide functionality with a simple user interface. The electronics systems are assembled in modular fashion for ease of removal or maintenance.

The Model 330, 340SC and 370SC Electronics System consists of:

System Controller Board; Video Processor Board; Video Amplifier Boards (3); Raster Timing Generator Board; Horizontal Deflection Board; Vertical Deflection Board; Lamp Ignitor; System Power Supply; High Voltage Power Supply.

There are also image and sync signal inputs, an LED display, two (2) RS-232 communication ports, and two (2) IR receivers for projector control.

The digital and analog circuits of the System Controller Board direct the operation of image and raster generation circuits as well as controlling the input/output and power supply operation of the HJT Model 330, 340SC and 370SC projector electronics systems.

The System Controller sets operating parameters of the system such as brightness and contrast, produces internal test patterns and generates on-screen overlays, and sets the timing for the raster generation to adjust phase, geometric corrections, uniformity corrections and convergence. The System Controller houses the program memory as well as the memory for all convergence and uniformity maps, and has the responsibility of controlling communication with the user, power to the other areas of the projector, and other necessary functions.

The Video Processor and Video Amplifiers select the desired input signal and process it to produce the CRT beam modulation necessary to produce an image on the raster.

2–4 Model 330, 340SC, and 370SC Service Manual

Chapter 2—Functional Descriptions

The Raster Timing Generator provides timing signals to the System Controller Board, selects the appropriate incoming sync signal and produces the timing signals for controlling the geometry of the raster.

The Vertical and Horizontal Deflection Boards produce their respective sweep currents to drive the deflection yokes. The Vertical Deflection Board also houses the convergence amplifiers that drive correction coils.

The System Power Supply provides all DC power below 200V to the projector. This includes the supply to the arc lamp/ignitor and the supply to the High Voltage Power Supply.

The High Voltage Power Supply provides all voltages of 200V and higher. This includes all CRT bias voltages except the cathode.

Image and sync inputs arrive in the projector at the Video Processor Board. Inclusion of the Decoder Board is optional. User communication is accomplished by on-screen displays, LED display output, IR remote input, or RS232 Input/Output. All of these devices are separate from, but communicate directly with the System Controller Board.

The detailed functional description of the subassemblies are covered below in the following order:

1. System Power.

2. Card Cage and Circuit Boards.

3. CRT Assembly.

4. Arc Lamp.

2.4 System Power

System Power Supply

The System Power Supply provides the connection between the external power source and the projector. The System Power Supply provides all internal DC power to the projector with the exception of that provided by the High Voltage Power Supply (Section 2.4.3). This includes the low voltage power to the electronics, the supply power to the HVPS, and the Arc Lamp power.

The System Power Supply is a AC-DC power supply with an input rectifier and protection circuit and several separate switchers; one (1) for Arc Lamp power, one (1) for +5V Standby power, one (1) for +24V Standby power, and others for the other low voltages.

All of the power supply outputs are protected against overvoltage and overcurrent. Overcurrent protection is a foldback circuit that limits the output current by reducing the output voltage when an overcurrent condition is detected. An overvoltage condition at the output of the supply will cause the affected voltage to be shut down until input power is removed and reapplied.

Model 330, 340SC and 370SC Service Manual 2–5

Chapter 2—Functional Descriptions

All of the SPS output voltages except Arc Lamp power are indicated by a LED display (see ). The LEDs are located on a bar-type display on the backplane at the left side of the card cage. The individual LEDs will be lit when the corresponding voltage is energized. The LEDs are wired to the SPS output power using only a current limiting resistor so when the LED is lit, it is an indication that there is a voltage present, not necessarily the correct voltage. To verify whether or not the voltage at the output is correct, a voltmeter must be used to probe the output connectors J500, J501, or J502.

+5V +5V

STB

Figure 2-2

A safety interlock switch is located on top of the power supply. The interlock

+24V

STB

+6.3V +15V -15V +24V +48V+107V -200V

Backplane Status Indicators.

switch shuts off the System Power Supply whenever the cover is removed. During normal operation with the cover installed, the switch is in the 'armed' position. When the rear cover is removed, the switch will be released and cause power to the projector to be interrupted. To run the unit without the cover installed, override the interlock switch by pulling it up into the 'service' position. When the cover is replaced, the switch will automatically be reset into the 'armed' position.

A circuit breaker is located on the right side of the System Power Supply. The circuit breaker serves to remove all power from the projector (except for the power at the input terminals) by switching it to the OFF position.

CAUTION!

The circuit breaker must be switched off, and the projector must be disconnected from AC power prior to performance of any maintenance, to ensure that all power is removed from the internal components of the projector. Normal operation of the System Power Supply is as follows:

When external power is applied, +5V Standby will always be energized as will the internal SPS fans. +24V Standby power for operating the fans will be energized whenever the lamp or electronics are turned-on and five (5) minutes after the projector is shut down.

All other voltages are controlled by the power-up or power-down commands issued by the operator.

2–6 Model 330, 340SC, and 370SC Service Manual

Chapter 2—Functional Descriptions

The Arc Lamp power supply is a current-controlled supply with an open circuit voltage of about 170V. When the Arc Lamp is operating at steady state, the power supply provides the current set by the technician. The output of the supply has a large capacitor that will, on initial ignition of the Arc Lamp, provide the very high initial current necessary to ionize the xenon gas in the lamp and sustain the arc. The current setpoint is initially set at the factory and must be reset by the technician whenever an Arc Lamp is replaced.

AC INPUT

220-240vac 50Hz

From System Controller

POWER FACTOR CORRECTION

/FANENBL

J502

Model 330. Model 340SC = +25V/80a; Model 370SC = +30V/100a.

∇

/LVPSNBL

/ALENBL

Figure 2-3

System Power Supply Block Diagram.

STANDBY/ I/O CONTROL

+5v, +24v

LOW VOLTAGE Power Supply +5v,+6.3v,+-15v, +24v,+48v,+107v

ARC LAMP Power Supply and Boost

+22v/68a +170v/1.0a

∇

J502

J500

J503 (-) J504 (+)

To Backplane

To Arc Lamp Via Ignitor

Normal system power-up (Electronics and Lamp):

1. Upon receipt of Power-On command, SCB pulls /FANENBL and /ALENBL lines low.

2. +24V Standby and Arc Lamp power supplies turn on.

3. When Arc Lamp lights (run voltage sensed by a window comparator in the SPS), SPS pulls /LAMPLIT line low.

4. When SCB senses /LAMPLIT low, SCB pulls /LVPSNBL line low.

5. Low voltage supplies turn on.

6. SCB senses +5V supply at correct level and enters normal program sequence.

Lamp only power-up:

1. Upon receipt of Lamp-On command, SCB pulls /FANENBL and /ALENBL lines low.

Model 330, 340SC and 370SC Service Manual 2–7

Chapter 2—Functional Descriptions

2. +24V Standby and Arc Lamp power supplies turn on.

3. When Arc Lamp lights (run voltage sensed by a window comparator in the SPS), SPS pulls /LAMPLIT line low.

4. SCB senses /LAMPLIT low and awaits further instructions.

Electronics only power-up:

1. Upon receipt of Electronics-On command, SCB pulls /FANENBL and /LVPSNBL lines low.

2. +24V Standby and Low voltage supplies turn on.

3. SCB senses +5V supply at correct level and enters normal program sequence, lamp can be turned on at any time.

Table 2-1

VoltageFa

+5v

+5v Stb

+6.3v

+15v

-15v

+24v

+24v Stb

+48v +107v +170v

System Power Supply Voltage Distribution

HV PS

CRT SCB HDB VDB VPB RTG VAB

Arc Lamp/ Ignitor

2–8 Model 330, 340SC, and 370SC Service Manual

Chapter 2—Functional Descriptions

*Current depends on projector model (see Table 0-1 in Safety Chapter). ** Model 340SC = 2000 Watts; Model 370SC = 3000 Watts.

Figure 2-4

System Power Supply Input/Output Diagram

Arc Lamp Ignitor

The ignitor consists of a step-up power supply, a spark gap, and a transformer. The Arc Lamp Ignitor is mounted under or next to the Arc Lamp. It provides the high voltage pulse necessary to ignite the Xenon Arc Lamp that is the illumination supply for the HJT Model 330, 340SC and 370SC projectors.

The System Power Supply’s Arc Lamp Supply section provides the necessary voltage to activate the ignitor and to sustain the arc in the Arc Lamp once it has been ignited. The SPS provides the power necessary to operate the ignitor.

The Ignitor is only active during the time between the Arc Lamp Power Supply energizing and the Arc Lamp igniting. During steady state operation and when the projector power is off, the ignitor is inactive.

Model 330, 340SC and 370SC Service Manual 2–9

Chapter 2—Functional Descriptions

When the Arc Lamp supply first turns on, it supplies 170V to the ignitor. The ignitor then senses this voltage, activates it’s on-board supply, and produces a 1µS, 38KV pulse to the Arc Lamp. This pulse strikes an arc in the lamp. The Arc Lamp supply then provides the high current necessary to sustain the arc in the lamp. Refer to Figure 2-5 and the summary below for a description on the Arc Lamp and Ignitor timing.

/FANENBL

/ALENBL

/LAMPLIT

38 KV

170V

22-30V

2 3 4

5 6

ARC LAMP ON

IGNITOR FIRES

CPU TIME-OUT 5-10 MINUTES

LAMP-OFF COMMAND

FAN DISABLE

LAMP-ON COMM A ND

22-30V depending on projector model.

Figure 2-5

Arc Lamp/Ignitor Timing Diagram Summary:

Arc Lamp Ignitor Timing Diagram

1. The operator powers Arc Lamp on. /ALENBL and /FANENBL from System Controller Board are pulled low. SPS receives /ALENBL from SCB and turns on the Arc Lamp PS.

2. Ignitor receives +170V boost voltage from the Arc Lamp PS.

3. Ignitor steps up the +170V boost voltage to a 1 µsec pulse, approximately 38KV.

4. Arc Lamp ignites from the 38kV pulse.

5. High current (about 68-100A depending on projector model) begins through Arc Lamp and voltage drops to +22-30V (depending on projector model).

6. /LAMPLIT signal goes to SCB to inform board that Arc Lamp is lit.

2-10 Model 330, 340SC, and 370SC Service Manual

Chapter 2—Functional Descriptions

High Voltage Powe r Supply

The High Voltage Power Supply is a DC-DC converter (see Figures 2-6 and 2-7) and is located on the left side of the CRT housing. It provides all necessary voltages for the CRTs except the cathode drive, which comes from +107V from the SPS.

Figure 2-6

Input power is +24V at 5A from the SPS. The input power is converted into the

High Voltage Power Supply

high voltage necessary to bias the CRTs. The HVPS is controlled by an enable line (/HVEN) originating at the Video

Processor Board. This enable line is controlled by logic that turns the HVPS off when there is a fault that could damage the CRTs. There are two (2) different conditions that could damage the HVPS:

1. If the +5V supply to the VPB is interrupted, the control and protection is compromised and the HVPS must be turned off.

2. If the cathode drive power is lost on one of the Video Amplifiers, the cathode current cannot be controlled and the HVPS is turned off.

3. Further details regarding this logic can be found in the functional description on the Video Processor Board in Section 2.6.4.

Model 330, 340SC and 370SC Service Model 2-11

Chapter 2—Functional Descriptions

The HVPS provides several voltages to the CRTs:

Anode Grid 1 Grid 2 Focus

+24v

GROUND

HDFOCUS

HDFOCUS RTN 8

VDFOCUS

/HVEN

Figure 2-7

2 3

High Voltage

9VDFOCUS RTN

Power and Control Connector

Power Supply

(Pins 1,4,5,10 not used)

RED ANODE GREEN ANODE BLUE ANODE

RED FOCUS GREEN FOCUS BLUE FOCUS

RED G2 GREEN G2 BLUE G2

-200v

High Voltage Power Supply Input/Output Diagram

12369

11258

10147

Figure 2-8

2-12 Model 330, 340SC, and 370SC Service Manual

HVPS Power and Control Connector Jack, J603

Chapter 2—Functional Descriptions

CRT 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.

Focus voltage (called Electronic Focus) is a modulated DC voltage. The DC level is set by the user during initial setup to focus the CRT electron beam. The Electronic Focus controls are located on the left side of the HVPS (see appropriate model Operator’s Manual). There are three (one for each color) ¾ turn pots for adjusting the Electronic Focus. Of the six (6) pots found on the HVPS, the bottom three (3) are for focus while the top three (3) are for G2 adjustment (Section 3.10). The DC voltage is modulated within the HVPS using the HDFOCUS and VDFOCUS input signals. VDFOCUS is the vertical dynamic focus signal, which is a waveform with parabolic shape at the vertical sweep frequency. HDFOCUS is the horizontal dynamic focus signal. It is a combination of the vertical dynamic focus signal and a parabolic waveform at the horizontal sweep rate. These two (2) signals are combined in the HVPS to form a composite dynamic focus signal. Dynamic focus is necessary to ensure that the CRT electron beam is converged to a point as the beam sweeps across the CRT face. Since the CRT faceplate is flat, the raster sweep causes a varying path length for the electron beam. This means the focus voltage must be varied as the raster is traced. Focus voltage cannot be conveniently measured during normal operation.

G2 screen grid voltage is a DC voltage that is set by the user. The three (3) adjustment controls, one for each color, consist of ¾ turn pots and are located on the left side of the HVPS immediately above the focus controls. This voltage is set during initial projector setup to adjust the black level on the screen (see appropriate model Operator’s Manual). The G2 voltage sets the bias on the screen grid of the CRT and is normally used to set the cutoff level. However, since the HJT light valve requires a non-zero input to produce a just-cut-off image on the screen, G2 is set to produce a slightly greater-than-black raster on the CRT. The G2 is adjustable from 100V to 1400V individually by color. The actual operating level will be near 1200V. G2 voltage cannot be conveniently measured during normal operation.

-200V is the supply to the control grid (G1) of the CRTs through the Video Amplifier Board. This voltage is not user controllable. The -200V is the only output voltage from the HVPS that goes to the backplane of the projector to be routed to the Video Amplifier, and uses the rear-most LED of the backplane LED bar for indication.

-200V is the only convenient means of directly observing whether or not the HVPS is turned on, either by observing the indicator LED on the backplane, or by probing the control connector with a voltmeter.

Model 330, 340SC and 370SC Service Model 2-13

Chapter 2—Functional Descriptions

As with the other indicators on that LED bar, the LED is in series with current limiting resistor, so a lit LED indicates only the presence of a voltage, not necessarily the correct voltage.

The control grid, G1, voltage is regulated to -81V during normal operation. During blanking, G1 is pulled to -111V. When the CRTs are disabled for protection, G1 is pulled to its maximum negative level of -200V, which can be measured, at the control connector, pin 6.

2.5 Card Cage

The Card Cage provides support and protection for five (5) circuit boards, the Phase Locked Loop and the optional Decoder Board in the HJT Model 330, 340SC and 370SC projectors. The five-(5) circuit boards are, from rear to front, the VPB, RTG, SCB, VDB, and HDB. Each circuit board has it's own keyed slot. A circuit board cannot easily be plugged into the wrong slot since the connectors will not match up.

Horizontal Deflection Board (HDB) P/N 102523

Vertical Deflection Board (VDB) P/N 102521

System Controller Board (SCB) P/N 104668

Raster Timing Generator and Phase Locked Loop

Video Processor Board

(RTG)

P/N 100568

(PLL)

(VPB) P/N 104672

and optional Decoder Board

Figure 2-9

Four (4) fans on the right side of the card cage cool the circuit cards in the card

Electronics Card Cage

cage. These fans are energized by the +24V standby power from the SPS. They start when either the Arc Lamp or the electronics are powered up and run for approximately five (5) minutes after the projector is shut down.

The five-(5) cards in the card cage are held into position by both the friction of the connectors and by a circuit board retaining bar. The circuit board retaining bar should always be installed during projector operation.

A lightweight top cover is included with the card cage. Eight (8) screws secure the cover. The cover provides for direction of air flow and for physical protection of the circuit cards contained in the card cage. The cover should always be installed when the projector is in operation to ensure adequate cooling of the circuit cards and to prevent foreign materials from falling into the electronics.

2-14 Model 330, 340SC, and 370SC Service Manual

The card cage is hinged in the rear to allow it to be folded backward for access to the CRT housing (when folding the card cage backward be sure that nothing is plugged into the rear electronic jacks or the plugs could be severely damaged). During normal operation, the card cage should be in its upright position to ensure proper cooling of the CRT enclosure.

A holddown screw is provided to secure the card cage and prevent it from rotating backward during shipping or when the projector is mounted in an upwardpointing position. The holddown screw is located on the lower, front, right corner of the card cage.

The rear panel of the card cage provides mounting for the projector controls. The VPB, which receives all image and sync inputs, is secured to the rear panel by four screws. The RS-232 control connectors and the IR receiver and repeater inputs as well as the LED dot matrix status display are located on the lower left of the rear panel. The projector model and serial numbers are also found on the rear panel.

2.6 Circuit Boards

Chapter 2—Functional Descriptions

The Model 330, 340SC and 370SC projectors have a total of twelve (12) accessible circuit boards. Seven (7) boards are located within the card cage (Figure 2-9) and five (5) are located outside the card cage (Table 2-2).

Table 2-2

No. Description

Ignitor

Video Amp Boards (VABS)

Backplane

Each circuit board can be replaced individually except the Backplane board and

Circuit Boards Outside Card Cage

330

102083 103567 100571

340SC

102207 103567 100571

370SC

104475 103567 100571

the PLL. The PLL is replaced with the RTG as a unit. The Ignitor was previously described in Section 2.4.2. The circuit boards covered in this Section are listed in Table 2-3.

Table 2-3

Page

2-18 Raster Timing Generator 2-26 Horizontal Deflection Board (HDB) 2-34 Vertical Deflection Board (VDB) 2-44 Video Processor Board

Circuit Board

Circuit Boards

(RTG)

(VPB)

P/N

100568 and PLL 102523 102521 104672

and optional Decoder Board 2-55 Video Amplifier Board 2-58 System Controller Board 2-70 Backplane Board

(VAB) (SCB)

103567 104668 100571

Model 330, 340SC and 370SC Service Model 2-15

Chapter 2—Functional Descriptions

Figure 2-10 on the following page provides an overall view of how the raster is produced. Details on the individual PCBs are provided in separate sections in this chapter.

2-16 Model 330, 340SC, and 370SC Service Manual

Chapter 2—Functional Description

Figure 2-10

Model 330, 340SC and 370SC Service Manual 2-17

Raster Generation Block Diagram

Chapter 2—Functional Descriptions

Raster Timing Generator Board (RTG) p/n 100568

The Raster Timing Generator board is located in the electronics card cage and plugs into the backplane. It is the second board from the rear of the card cage and consists of a main board and the PLL daughter board (see Figure 2-11). The PLL board must be installed for the projector to operate.

Figure 2-11

2-18 Model 330. 340SC, and 370SC Service Manual

Raster Timing Generator Block Diagram

The following functions are provided by the RTG:

Internal sync generation. Sync detection and selection. Serration and equalization pulse removal. Timing clock pulse generation. VSYNC separation and field detection. Timing for several geometry and correction functions. Serial communication with the SCB.

The block diagram ( see Figure 2-11) description, along with the I/O description in the

Chapter 2—Functional Description

Section following, provide information for module-level troubleshooting.

Sync Generator

The sync generator takes its input from the System Controller Board. The SCB provides a 4MHz clock signal, SYSCLK, which is used to generate a HDTV-like sync signal. The internal sync signal generated is a 33.33KHz horizontal, 59.3Hz vertical, interlaced signal. Because simply counting down from the 4MHz clock generates it, the actual signal that is produced is a square wave signal. The square wave does not affect normal operation of the projector but will cause a vertical bar to be generated on the screen when the projector is operating on the internal sync with the DC restore timing set to BP or TL.

Sync Detector and Selector

The Sync Detector and Selector take inputs from the Video Processor Board. The VPB sends the three (3) sync signals, SGSYNC (sync on green), HCSYNC (horizontal or composite sync), and VSYNC (vertical sync only) of any polarity to the RTG. These are the sync signals that come from the external source and are what the projector will genlock to when they are available. The sync selector uses a pre-determined priority to determine which of these sync signals will be used, based on which signals are present at the input.

The pre-determined priority to determine which sync signals used is:

1. Separate H and V sync will be used if both are available on their respective sync inputs,

2. Composite sync on the HSYNC input will be used if available and no sync signal is present on the VSYNC input,

3. Composite sync on the green image input will be used if no coherent sync signal is available on the HSYNC input.

If no external sync signal is detected on the three (3) sync input lines, the RTG will send out a signal to the SCB via the IIC interface indicating that there is no sync present (/External Sync Detect). The SCB will then make a determination whether or not to command the RTG, via the IIC interface, to select internal sync (Internal Sync Forced).

The selected sync signal(s) is inverted, if necessary, to provide the negative-going sync signal needed by the downstream circuits.

Model 330, 340SC and 370SC Service Manual 2-19

Chapter 2—Functional Descriptions

Serration and Equalizati on Lockout

The Serration and Equalization Lockout takes a composite sync signal and removes any equalization and serration pulses from it. The Model 330, 340SC and 370SC projectors do not require these pulses to operate. Removal of the serration and equalization pulses provides a faster, more reliable response to the vertical sync and subsequent relock to horizontal sync. This circuit uses the 4xHsync clock that is generated in the PLL to delete any sync information present in the center portion of the incoming horizontal waveform.

Phase Locked Loop

The PLL receives horizontal sync stripped of the serration and equalization pulses from the Serration and Equalization Lockout circuit.

The Horizontal Sync signal is fed to horizontal frequency decoder which uses a frequency/voltage circuit to pre-tune the VCO of the PLL to ensure proper locking. The Horizontal Frequency Decoder also provides a count of the number of horizontal lines per frame. The H count is then sent via the IIC interface, to the SCB (HCOUNT). The SCB uses this information to set up the correction and overlay maps and to calculate the H frequency.

The PLL takes in the horizontal sync signal and generates a clock signal that is a square wave of 224 times the horizontal frequency. The PLL will perform this function over the entire range of horizontal frequencies, 15KHz to 90Khz. It will maintain that signal over the full period of the raster including the vertical sync pulse. Counters in the PLL circuit also provide clock signals with frequencies of Hx112, Hx4, Hx2, and Hx1. These clock signals are square wave signals and are phase-coherent with respect to the H sync signal. The Hx224, Hx112, and Hx1 signals are used on both the RTG and the SCB for timing of corrections and raster adjustment. The signals that go to the SCB are Hx224, Hx112 (clock signals), and /HSYNCR (regenerated HSync, a negative-going pulse signal that is timed to be on the leading edge of the Hx1 clock). The Hx4 and Hx2 clocks are used exclusively on board the RTG for sync detection and timing.

Control of phase noise is critical—jitter will translate into a "smearing" of the projected image. Therefore, if the PLL loses lock, the /Phase Lock signal is sent to the SCB via the IIC interface. The SCB then makes a decision based on that information.

VSYNC Detector, Field Separator, and Mux

The VSync detector uses the Hx2 clock signal to detect the vertical sync signal from the composite external sync signal that arrives on either the HSYNC input or the sync-ongreen input.

The field separator determines whether or not the signal is interlaced and, if so, which field is currently being displayed. This information is sent to the SCB as the signals INTI (interlace indication, high if interlaced), /FIELD1 (low when the field number 1 is current), and /FRAMEST (indicates the beginning of a new frame).

The mux takes the external Vsync and field signals and multiplexes them with the internal sync signal to select which will be used. The multiplexed Vsync signal is pulse-

2-20 Model 330. 340SC, and 370SC Service Manual

Chapter 2—Functional Description

shaped to be three (3) horizontal periods in length. This signal, /VSYNCSC (pulseshaped vertical sync) is then sent to the SCB and the VPB.

Adjustment Counters

The adjustment counters implement the following timing functions:

Left side, right side, top side, and bottom side blanking. Vertical and horizontal timing for convergence correction and overlay. Pincushion and linearity correction timing. Vertical phase. DC restore timing.

The four-(4) sides' blanking adjustments are accomplished by counting from the regenerated H and VSYNC signals respectively. Each adjustment is independent of the others. Vertical blanking is accomplished by counting a specified number of horizontal lines after the vertical sync signal out of the VSYNC Mux. The top blanking counts the commanded number of lines then unblanks the picture. The bottom blanking counts the commanded number of lines then blanks the image.

Horizontal blanking is accomplished by counting a specified number of Hx224 clock pulses after the regenerated HSYNC pulse, /HSYNCR). The left side blanking counts the commanded number of clock pulses then unblanks the image. The right blanking counts the commanded number of clock pulses then blanks the image. The outputs from these counters are combined with a signal indicating PLL lock, into a composite blanking signal VIDBLANK (high when the image is to be blanked) that is sent to the VPB. The user selects the actual position of the four sides' blanking by adjusting from the remote control.

The SCB calculates the number of clock pulses to count for each of the four sides based on the input from the user, and sends those numbers to the appropriate counters via the IIC serial communication bus signals LBlank, RBlank, TBlank, and BBlank.

Adjustment counters also generate the convergence correction and overlay address generators’ timing signals. The correction bit-map address counter's MAPST (timing pulse to tell the correction and overlay address generators to start a new frame) timing pulse is generated by counting the commanded number of /HSYNCR pulses since the vertical deflection flyback start pulse. The /CORSTRT (signal that indicates to the SCB when to start the correction and overlay address generators counting) timing signal is a pulse signal sent to the SCB. Its timing is determined by counting the commanded number of Hx224 pulses after the /HSYNCR signal.

The position of the overlays (including menus and test patterns) and correction maps is controlled automatically in the vertical direction. In the horizontal direction, the user controls the position via the MENU POSITION selection under the TIMING SETUP MENU. This circuit also determines the phase between the regenerated HSYNC and the HV Flyback from Deflection. This value is read by the SCB over the IIC bus.

The pincushion and linearity correction timing signal is a pulse signal called /PCST that is sent to the Vertical Deflection Board. The signal is generated using the same timing

Model 330, 340SC and 370SC Service Manual 2-21

Chapter 2—Functional Descriptions

method as the /CORSTRT signal but has a separate command from the SCB. It controls the timing of the top and bottom pincushion correction, top and bottom keystone correction, and horizontal linearity correction. The signal timing is selected by the user and controlled by the SCB. Adjusting P controls it.

Vertical phase adjustment is accomplished by timing the /VFBST (vertical start) signal with respect to the regenerated vertical sync signal. This signal is generated by counting a commanded number of horizontal lines after the vertical sync signal /VSYNCSC. The signal timing is selected by the user and controlled by the SCB. It is controlled by adjusting PHASE using the up/down arrows.

DC restore timing determines the point in time that the signal is clamped and the DC restore (Section 2.6.4, Video Processor Board) function is accomplished. The user has three (3) choices from which the DC restore timing can be selected. These are Backporch (BP), Tri-level (TL), and Sync-tip (ST). The choices are selected in the SL column of the C

HANNEL LIST

The DC restore timing counts a preset number of Hx224 clock pulses after the HSYNC

under the C

HANNEL MENU

signal leading edge. ST will clamp and DC restore during the time that the HSYNC pulse is active. ST clamping is timed with respect to the leading edge of the HSYNC pulse. It is seldom used but is necessary when there is no back porch to clamp on (image starts immediately after the sync pulse). BP will clamp and DC restore shortly after the HSYNC pulse. BP clamping is timed with respect to the trailing edge of the HSYNC pulse. The timing is calculated to be on the back porch of the signal (after the sync pulse but before the image begins). This is the most frequently used clamp timing.

INCUSHION POSN

under the T

(Figure 5-1, Menu Structure).

IMING SETUP MENU

The default setting for the DC restore timing is BP when a new channel is set up. TL clamping occurs significantly after the HSYNC pulse. The purpose of TL timing is to provide DC restore timing that is compatible with the Tri-level type sync used with HDTV signals. Like BP, TL clamping is timed with respect to the trailing edge of the HSYNC pulse. The output of the Synctip/Backporch circuit is a pulse signal (DCRSTR) going to the VPB.

Serial Communication

The RTG uses only the IIC bus for serial communication with the SCB (Section 2.6.6). The information transferred over the IIC bus is indicated below (I = input to RTG, O = output from RTG). A change in output data generates an interrupt pulse.

Table 2-4

I/O

I I

IIC BUS Information

Information

Priority Select

Description

Commanded sync selection priority

(always fixed as described above).

Vertical Flyback Start Delay Commanded V phase.

Map Start Delay

Commanded timing for vertical positioning

of correction map.

L Blank

R Blank

Commanded position of left blanking.

Commanded position of right blanking.

2-22 Model 330. 340SC, and 370SC Service Manual

Chapter 2—Functional Description

O O O O

T Blank

I I I

B Blank

/STBP

Commanded position of top blanking. Commanded position of bottom blanking. Command for DC restore timing on either

leading or trailing edge of sync pulse.

DC Restore Delay

Commanded timing of DC restore after

reference edge of sync pulse.

Internal Sync Forced

I I I

Correction Start Delay

Pincushion Start Delay

Command to force internal sync select. Commanded H phase of correction map. Commanded H phase of pincushion, keystone,

and linearity correction.

2H Sync Enable

I I

Shifted Sync Enable

/External Sync Detect

HCount /Phase Lock Phase Count

Command determines path of H sync signal. Command determines path of H sync signal. Is an external sync available.

Count of H lines per frame. Indication of PLL lock. Indication of phase difference between

HSYNC and HFlyback.

Raster Timing Generator I/O

This section provides a description of the inputs to and outputs from the RTG. 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 signal's direction is noted, with input referring to an input to the RTG, and output to an output from the RTG. (e.g.: under System Controller Board “Input”; SYSCLK refers to the signal SYSCLK that is an input to the RTG from the System Controller Board). When test points are provided for the I/O they are noted.

Table 2-5

Inputs

SYSCLK 4 MHz clock signal for derivation of internal HDTV sync signal.

IICCLK

Outputs

/IICINT

/Hx224

Raster Timing Generator I/O Signals

System Controller Board

Description

(TP 13)

IIC clock line. Unidirectional clock line for control of

synchronous data transfer over IIC data bus.

Description

IIC interrupt line. Signal line for slave boards to inform the SCB

(master) that there is data to be transferred. Master then polls slaves to determine the source of the interrupt.

Square wave signal 224 X the horizontal frequency for overlay

address generator clocking. (TP 23)

Model 330, 340SC and 370SC Service Manual 2-23

Chapter 2—Functional Descriptions

/Hx112

112 times the horizontal frequency for convergence and Z axis

correction address generator clocking. (TP 20)

/CORSTRT Signal used to start the convergence and overlay address

generators during each horizontal sweep. (TP 4)

/FRAMEST Indicates the beginning of a frame. Used in the SCB for

counting vertical frequency. (TP 5) INTI /VSYNCSC Regenerated vertical sync signal, pulse shaped to 3 horizontal

Indicates when input source signal is interlaced. (TP 2)

lines in width. (TP 7) /FIELD1 /MAPST

Low during field #1 of an interlaced input source. (TP 8) Pulse signal to signal the overlay and correction address

generators to reset for a new frame. (TP 12)

I/O

IICDATA

IIC data line. Bi-directional serial line for synchronous data

Description

transfer between SCB and other circuit boards. See detailed

description for list of signals transferred and data direction.

Inputs

SGSYNC

Description

Stripped Green Sync is Sync-on-Green composite sync signal.

Video Processor Board

(TP 10) HCSYNC VSYNC

Outputs

DCRSTR

Horizontal/Composite Sync. (TP 9) Vertical Sync used only for separate H and V sync. (TP 21)

Description

Pulse for DC restore timed to correspond to ST, BP, or TL.

(TP 1) VIDBLNK Signal for image blanking from adjustment counters. (TP 6) /VSYNCSC Vertical sync signal pulse for ILA bias sync. (TP 7)

Inputs

/HVFLBCK Signal representing horizontal flyback from the HDB. Used for

Description

Horizontal Deflection Board

determining H phase. (TP 17)

Outputs

/VFBST /HSYNCRE Selected HSYNC signal. (TP 14)

Outputs

/PCST

Description

Signal to start the vertical retrace. (TP 11)

Vertical Deflection Board

Description

Signal to time the start of T/B pincushion and linearity

correction. (TP 31)

2-24 Model 330. 340SC, and 370SC Service Manual

Inputs

+15V

Description

Power for the analog section of the RTG including the PLL.

System Power Supply

Chapter 2—Functional Description

(TP 30)

-15V

Power for the analog section of the RTG including the PLL.

(TP 29) +5V AGND DGND

Power for the digital portions of the RTG. (TP 3) Return for +/-15V, separated from DGND by an inductor. Return for +5V, separated from AGND by an inductor.

Interlocks and Protection

This section describes the interactions between boards where one (1) board may cause others to perform protection functions.

Input

None

Output

If the PLL falls out of sync, a signal indicating an out-of-lock condition (/PLOCK) will be sent to the SCB.

Internal

When no external sync signal is present, the RTG will select it's internal sync signal, thus preventing the need to provide another source for overlay generation.

Horizontal Deflection Board P/N 102523 (HDB)

The horizontal deflection board plugs into the electronics card cage and is the forwardmost card in the card cage.

The following functions are provided by the HDB:

Drive main horizontal deflection coils to provide horizontal raster scan.

Horizontal raster centering. Horizontal width adjustment. Side pincushion correction. L/R keystone correction. Horizontal sweep reversal. Horizontal phase adjustment. Oscillator for vertical deflection.

The block diagram (see Figure 2-12) description and the I/O description, in the section following, provide information to perform module level troubleshooting.

Model 330, 340SC and 370SC Service Manual 2-25

Chapter 2—Functional Descriptions

Figure 2-12

Horizontal Deflection Board Block Diagram

Vertical Oscillator

The function of the vertical oscillator is to lock to the vertical signal, /VFBST, sent by the RTG, and produce a pulsed output, VERTDR, of the same frequency. The /VFBST signal initially is sent to a Frequency to Voltage converter to provide a program voltage to the oscillator. This presets the oscillator frequency so the oscillator then is able to lock to the incoming vertical sync signal.

2-26 Model 330. 340SC, and 370SC Service Manual

The purpose for having an oscillator for the vertical sweep circuit is to maintain a sweep

Chapter 2—Functional Description

even in the event of loss of vertical sync signal to prevent damage to the CRT. The vertical oscillator has a free-run frequency of approximately 35Hz when there is no input.

Horizontal Phase Locked Loop

The incoming signal, /HSYNCR initially is sent through a Frequency to Voltage converter. The output from the F to V is used to provide a program voltage to the PLL, set the horizontal phase adjustment range, and to set the frequency of the horizontal power supply. The Horizontal PLL, like the vertical oscillator, takes the input pulsed signal, /HSYNCR, from the RTG, locks to it, and produces a pulsed output of the same frequency. The Horizontal PLL has the additional function of controlling the phase of the output signal relative to the input signal. To do this, the horizontal PLL receives an input from the SCB via the serial bus that indicates the desired phase relationship. The incoming signal /HSYNCR is then compared with the flyback pulse (derived separately from the /HVFLBCK signal listed in the I/O section) to measure the phase relationship. To control horizontal phase, the operator presses the PHASE button on the remote control, then adjusts phase with the left and right arrow keys. As with the vertical oscillator, the Horizontal PLL provides for a minimum free-run frequency in the event of loss of horizontal sync signal. That frequency is approximately 12.5kHz.

Horizontal Centering

Horizontal centering of each raster (R, G, and B) is accomplished by applying a direct current bias to each horizontal deflection coil. The DC comes from a programmable current source that is in series with the main deflection coil. The current source is capable of providing either positive or negative polarity. Control input to the current sources comes from the SCB via the serial interface. Pressing the POS (Position) button on the remote control, then selecting the desired color can independently control the centering of each individual color. The left and right arrow keys are then pressed to adjust horizontal position. When controlling the position, Green is a master, i.e.: when Green is selected, all three-(3) colors move. Red and Blue are independent.

Horizontal Power Supply

The horizontal power supply is a switching power supply that provides an output voltage proportional to the horizontal frequency and width. The variable output of the power supply is a negative voltage providing a sink for the horizontal deflection current. The trace speed of the CRT spot will be determined by the voltage applied across the deflection coil. The voltage at the power supply output directly determines this in turn. So when the output from the power supply increases, a given width of raster can be obtained in a shorter period of time, thus supporting a higher horizontal frequency. In addition to providing for the maintenance of a constant raster size for varying frequency, a variable power supply is also necessary for control of the raster width. The output voltage of the horizontal power supply is controlled primarily by two (2) inputs.

Model 330, 340SC and 370SC Service Manual 2-27

Chapter 2—Functional Descriptions

The first is an input derived from the F to V in the horizontal PLL circuit. This presets the output of the supply to a voltage that will provide a nominal raster size for the horizontal frequency applied.

The second input is provided by the SCB via the serial interface. This input allows control of the raster width by the operator. To control the raster width, the operator presses the SIZE button on the remote control. Pressing the left and right arrow keys then controls the width. The three (3) rasters are not remotely controllable on an individual basis. They can however, be set individually with respect to each other by adjusting the cores of the variable inductors mounted on the yoke terminal boards (see appropriate model Operator’s Manual).

Flyback Switching

Flyback switching, necessary to avoid overscan and excessive power consumption over the wide range of horizontal frequencies covered, is accomplished using relays. When the input source is changed, the relays are switched to change the response of the resonant flyback circuit. Since horizontal flyback necessarily causes very high voltages, the relays must not be switched while under load. When the SCB commands flyback switching to occur, the switching circuit sends a signal to the GRN Horizontal sweep failure circuit to turn off the CRT beams. It also sends a signal to the Horizontal Power Supply to turn it off and shut down the horizontal sweep. The relays are then switched and the sweep and CRT beams are allowed to return to normal. This sequence of events will occur each time the input source to the projector changes, regardless of any line rate changes. There are four frequency bands and flyback times that can be set. The frequency ranges and flyback times are: 6.6uS @ 15-25.1kHz, 4.1uS @ 25-33.1kHz, 2.9uS @ 33-60.1kHz, and 2.4uS @ 60-90kHz. Flyback switching is not manually controllable by the operator.

Geometric Correction

The HJT Model 330, 340SC and 370SC projectors provide the ability to obtain a rectangular raster when shooting off-axis in the vertical direction from the screen. This ability is provided by left/right keystone correction. A geometric correction signal, GEOCORR, for controlling both the L/R keystone correction and the L/R pincushion correction is obtained from the Vertical Deflection Board. The GEOCORR signal is a periodic signal composed of a parabolic summed with a ramp signal, both at the vertical frequency. This signal is used to vary the width of the horizontal sweep as the vertical sweep progresses. It does this by modulating the negative voltage applied to the power transistor, thereby modulating the horizontal width of the raster. The components of GEOCORR, pincushion correction and keystone correction, are individually controllable by the operator (see appropriate model Operator’s Manuals).

Output Section

The horizontal sync pulse signal produced by the Horizontal PLL is applied to the output section to control the timing of the horizontal sweep. The output section includes the power output transistor, base drive circuit, reversing connectors, and interlock circuit.

2-28 Model 330. 340SC, and 370SC Service Manual

The three (3) horizontal deflection coils (B, G, and R) are driven in parallel by a single

Chapter 2—Functional Description

drive circuit and transistor. This is the reason for the inability to remotely control the three (3) raster widths independently. Since the deflection coils are in parallel, it is imperative that they all be connected prior to applying sweep voltage—the interlock circuit ensures this. An output from the Horizontal Power Supply is sent, in series, through all three (3) yoke connectors. This is part of the bias voltage used to operate the base drive circuit for the output section. Thus, if any of the yoke connectors is not connected, the output transistor will not turn on, and no horizontal sweep will be present.

There are two (2) output jumpers on the board, J500 and J501. Their function is to reverse the direction of the current through the horizontal deflection coils for front and rear projection. The output cable shall be connected to J501 for rear projection and J500 for front projection (Jumper Settings, Section 3.9).

Horizontal Sweep Failure Detection

Protection of the CRT from spot burns is accomplished by never allowing the CRT to continue to have beam current when there is no deflection. To this end, the HDB has a sensing circuit that detects when there is a loss of sweep that may cause CRT damage. This circuit senses the horizontal flyback voltage and frequency. By sensing both amplitude and frequency, the projector is able to maintain sweep over the widely varying input conditions allowed and still protect the CRTs from damage. The flyback signal is AC coupled and peak detected, then compared with a reference. As long as the flyback amplitude and frequency are above the minimum allowed, the sweep detection outputs (HSENSBLU, HSENSGRN, and HSENSRED) are pulled high. These signals are sent to the VDB for processing.

Serial Communication

The HDB uses two (2) separate, interrelated serial data communication systems to communicate with the SCB; the IIC bus, and a differential, synchronous data bus. The information transferred over the serial busses is indicated below (I = input to HDB, O = output from HDB). Also noted is whether the information is transferred over the IIC or the serial bus. A change in output data generates an interrupt pulse.

Table 2-6

Bus

IIC

I/O

HDB Serial BUS Information

Information

Flyback switch select

Flyback switch pulse

Front/Rear indication

Floor/Ceiling

Two bits that select one of four flyback switching

Pulse signal that commands the flyback relays to

TTL level that indicates whether the projector is

indication

Description

times (see detailed description)

switch.

in front screen mode (high) or rear screen (pulled low).

in the upright mode (high) or inverted mode (pulled low).

Model 330, 340SC and 370SC Service Manual 2-29

Chapter 2—Functional Descriptions

Bus

IIC

I/O

Information

Serial data load

Description

Command to the serial data receiver that the

incoming data is to be read. Serial Serial

I I

HPHASE HLINR

Commanded horizontal phase of picture. Commanded amount of overall H linearity

correction. Serial

TBKEY

Commanded amount of top and bottom Keystone

Correction. Serial Serial Serial Serial

I I I I

HCENTBLU HCENTGRN HCENTRED WIDTH

Commanded horizontal position of blue raster. Commanded horizontal position of green raster. Commanded horizontal position of red raster Commanded width of raster

Horizontal Deflection Board I /O

This section provides a description of the inputs to and outputs from the HDB. 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 signal's direction is noted, with input referring to an input to the RTG, and output to an output from the HDB. (e.g.: under Raster Timing Generator 'Input'; /VFBST refers to the signal /VFBST that is an input to the HDB from the Raster Timing Generator). When test points are provided for the I/O they are noted.

Table 2-7

Inputs

IICCLK

Horizontal Deflection Board I/O Signals

System Controller Board

Description

IIC clock line. Unidirectional clock line for control of synchronous data

transfer over IIC data bus.

+SERCLK

Serial data transfer clock (+). Unidirectional, differential clock line from

SCB to other circuit boards. Used for synchronous control of serial communication over SERDATA data lines.

-SERCLK

Inputs

+SERDATA Serial data transfer. Unidirectional, differential, synchronous serial data

Serial data transfer clock (-).

System Controller Board

Description

communication line. Used for transferring data from SCB to other circuit boards. Uses SERCLK and IIC for control of receiver.

-SERDATA Serial data transfer

Outputs

/IICINT

Description

IIC interrupt line. Signal line for slave boards to inform the SCB (master)

that there is data to be transferred. Master then polls slaves to determine the source of the interrupt.

I/O

2-30 Model 330. 340SC, and 370SC Service Manual

Description

Chapter 2—Functional Description

IICDATA

IIC data line. Bi-directional serial line for synchronous data transfer

between SCB and other circuit boards. See detailed description for list of signals transferred and data direction.

Inputs

/VFBST /HSYNCR

Outputs

/HVFLBCK Pulse signal representing horizontal flyback used to determine phase of

Description

Signal to control the vertical oscillator frequency and retrace timing Regenerated horizontal sync signal

Description

Raster Timing Generator

image

Inputs

GEOCORR FLRCLING TTL level indicating whether or not raster is inverted

Outputs

VERTDR HLINR HFDBK WIDTH TBKEYCOR DC voltage representing commanded top and bottom keystone correction HSENSRED DC voltage, high when flyback pulse for red yoke is present at normal

Description

Periodic signal for L/R keystone and L/R pincushion correction

Description

Pulse output from vertical oscillator. DC voltage controlling horizontal edge linearity correction DC voltage proportional to the H power supply output voltage DC voltage indicating commanded width.

Vertical Deflection Board

frequencies. HSENSBLU Similar to HSENSRED. HSENSGRN Similar to HSENSRED.

Inputs

/INLCK

Outputs

+INLCK

Description

Return from series daisy-chain for sensing yoke connectors installed.

Description

Negative voltage supply from the horizontal power supply to the daisy-

Main Horizontal Deflection Coils

chained yoke connector interlock. +BHORYK

Positive supply from the centering current source to the blue horizontal

main deflection coil.

-BHORYK

Return from the blue horizontal main deflection coil to the horizontal

deflection power transistor. +GHORYK Similar to +BHORYK.

-GHORYK +RHORYK

-RHORYK

Model 330, 340SC and 370SC Service Manual 2-31

Similar to -BHORYK. Similar to +BHORYK. Similar to -BHORYK.

Chapter 2—Functional Descriptions

Inputs

+48V +15V

-15V +5V GND

Description

Power for horizontal deflection Power for the analog section of the HDB Power for the analog section of the HDB Power for the digital devices on the HDB Return for HDB

System Power Supply

Interlocks and Protection

Input

None

Output

HSENSRED - Used to shut down the CRT beams in the event of horizontal sweep failure.

HSENSGRN - Identical to HSENSERED. HSENSBLU - Identical to HSENSERED.

Internal

+INLCK

Prevents the horizontal output section from being turned on when 1 or more deflection coils not connected.

-INLCK

Part of +INLCK circuit.

Minimum Frequency on Oscillators and PLLs

Ensures that there will be a sweep in both the horizontal and vertical directions when the sync pulse disappears. This is for protection of the CRT phosphor.

Vertical Deflection Board P/N 102521(VDB)

The Vertical Deflection Board plugs into the electronics card cage and is the second board from the front in the card cage.

The following functions are provided by the VDB:

Drive main vertical deflection coils to provide vertical raster scan for all three (3) CRTs.

Drive all correction coils to provide convergence and geometry correction.

Scan failure detection for all six main deflection circuits. Vertical size adjustment. Vertical linearity adjustment.

2-32 Model 330. 340SC, and 370SC Service Manual

Vertical raster centering. Top and bottom pincushion correction. Top and bottom keystone adjustment. Horizontal overall and edge linearity adjustment. Left and right pincushion and keystone correction

Chapter 2—Functional Description

waveform generation. Sweep reversal for normal and inverted operation. Generation of wave forms used for dynamic focus.

The block diagram (see Figure 2-13) description, along with the I/O description in the following section, provide information for module level troubleshooting.

Component numbering on the VDB, in general, follows the pattern that 2XX refers to components for Green deflection, 3XX refers to Blue, 4XX refers to Red (e.g.: R428 is a resistor in the red deflection amplifier). Likewise, the correction amplifiers are numbered 5XX for Green, 6XX for Blue, and 7XX for Red.

Model 330, 340SC and 370SC Service Manual 2-33

Chapter 2—Functional Descriptions

Figure 2-13

Vertical Deflection Board

Vertical Preamps

The vertical preamps (B, G, and R) each generate a ramp signal with the frequency determined by the incoming signal VERTDR from the Horizontal Deflection Board. The ramps generated in the preamp section have their common amplitude set by the commanded height and are corrected for vertical linearity (linearity is individually adjustable by R211, R311, and R411 and raster height is individually adjusted by R228, R328, and R428). The common raster height is adjusted by a signal sent from the SCB to the VDB via the serial bus. To control height, the operator presses the SIZE button on the remote control, then adjusts height with the up and down arrow keys. The ramp by the red preamp is used elsewhere in the VDB for the generation of correction signals.

2-34 Model 330. 340SC, and 370SC Service Manual

generated

Chapter 2—Functional Description

Vertical Amplifiers

The Vertical Amplifiers take the ramp signals generated by the Vertical Preamps and provide further modification prior to driving the vertical deflection coils. Individual centering signals, set by the operator and controlled by the SCB are inserted in the Vertical Output Amps to provide offset for each vertical sweep. The centering of each individual color can be independently controlled by pressing the POS (Position) button on the remote control then selecting the desired color. The up and down arrow keys are then pressed to adjust vertical position. When controlling the position, Green is a master, i.e. when Green is selected, all three (3) colors move. Red and Blue are independent. After the centering signal is summed with the ramp signal, the result is amplified to produce the required amplitude signal to drive the main vertical deflection coils.

The Vertical Amplifiers output is sent to jumpers for reversing the direction of the vertical sweep for inverted operation. Jumpers J200, 300, and 400 are used for normal operation while J201, 301, and 401 are used for inverted operation. A signal is sent to the SCB indicating which mode of operation the jumpers are specifying.

Sweep Failure Detection

Current through the vertical deflection coil is sensed and that signal used to drive a sweep indication circuit. There is one (1) circuit for each of Green, Blue, and Red. The sweep indication circuit combines the vertical current signal with the horizontal flyback signal. The signals from Green, Blue, and Red are then combined to produce a signal, /SWEEPOK, that is sent to the VPB and indicates the health of all of the six (6) sweeps.

In addition to the /SWEEPOK signal, there are six (6) LEDs on the VDB which indicate the presence of the individual sweeps. The LEDs indicating vertical sweep health (LED200, 300, and 400) are driven by the vertical sweep signal alone. The horizontal sweep signals affect both of the appropriate color LEDs (e.g.: if the Blue vertical sweep fails, LED300 would turn off, but if the Blue horizontal sweep fails, LED300 and LED301 would both turn off).

Side Pincushion and Keystone Correction

This circuit uses the ramp from the Red preamp to generate a variable amplitude parabolic waveform for use in L/R pincushion correction. The Red ramp is also used to generate a variable amplitude and polarity ramp for L/R keystone correction. Both the L/R pincushion and keystone are controlled by the SCB sending a signal over the serial bus. The operator can control the L/R pincushion by pressing the PIN button on the remote control. The left and right arrow keys are then used to vary the amount of pincushion applied. Pressing the KEY button on the remote control can control the L/R keystone correction. The left and right arrow keys are then used to vary the amount of keystone correction applied. The two (2) waveforms are then summed.

This signal is then multiplied by HFDBK from the HDB. The resultant signal, GEOCORR, is sent to the HDB to modulate the horizontal width for side pincushion and keystone correction.

Model 330, 340SC and 370SC Service Manual 2-35

Chapter 2—Functional Descriptions

A form of the vertical frequency parabolic waveform that is derived from the red ramp is also sent out to the VPB as VPARAB for use in the dynamic focus circuit.

Horizontal Linearity Correction

The Horizontal Linearity Correction section provides correction for both horizontal overall linearity, and horizontal edge linearity. The WIDTH signal from the HDB and the /PCST signal from the RTG are combined to form a periodic ramp signal with horizontal frequency. The ramp signal is used to form a parabolic signal, again with horizontal frequency. This signal and a signal commanded by the operator, HLINCORR, combine to form a variable polarity and amplitude parabolic signal with horizontal sweep frequency. This signal is used for overall horizontal linearity correction. The parabola and ramp signals are also combined with the HLINLR signal, imported from the HDB, to produce an S-curve signal of variable polarity and amplitude, also with horizontal sweep frequency, to be used for edge linearity correction.

The operator can control each of these correction functions from the remote control by pressing the LIN key for overall linearity adjustment, or the EDGE key for edge linearity adjustment. The left and right arrow keys are then used to make the adjustments. The Scurve and parabola are then summed and sent to the Green, Blue, and Red X-correction amplifiers where the corrections are applied to the correction coils. The parabolic signal noted above, is also sent out to the VPB as HPARAB to be used in dynamic focus.

Top and Bottom Pincushion and Keystone Correction

A parabolic signal is borrowed from the horizontal linearity correction section for T/B pincushion correction. It is combined with an operator command signal, TBPNCORR, to produce a variable amplitude and polarity parabolic signal with horizontal sweep frequency.

A ramp signal, also from the horizontal linearity section, is used for T/B keystone correction. It is combined with an operator command signal, TBKEYCOR, to produce a variable amplitude and polarity parabolic signal with horizontal sweep frequency.

Both the T/B pincushion and keystone are controlled by the SCB sending signals over the serial bus. The operator can control the T/B pincushion by pressing the PIN button on the remote control. The up and down arrow keys are then used to vary the amount of pincushion correction applied. Pressing the K the T/B keystone correction. The up and down arrow keys are then used to vary the amount of keystone correction applied.

These two (2) signals are combined with the red ramp, having the frequency of the vertical sweep, from the vertical pre-amp, to produce the top and bottom pincushion and keystone correction waveform. This signal is then sent to the Green, Blue, and Red Ycorrection amplifiers. The operator can control the phase relationship of the T/B pincushion, T/B keystone, and horizontal linearity, with respect to the picture.

button on the remote control can control

To control these parameters, the operator selects PINCUSHION POSN from the TIMING SETUP MENU under the MAIN MENU. The left and right arrow keys are then used to vary the position of the corrections.

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Chapter 2—Functional Description

Correction Amplifiers

There are six (6) correction amplifiers. Each one receives a real-time convergence correction signal:

RXCORR. RYCORR. GXCORR. GYCORR. BXCORR. BYCORR, from the SCB convergence section.

The X-correction amplifiers, R, G, and B, also receive the horizontal linearity signal. The horizontal linearity signal is then combined with the appropriate color's X-correction signal to produce a composite horizontal correction signal. The Y-correction amplifiers, R, G, and B, receive the top and bottom pincushion and keystone correction signal. The pin and key correction signal is then combined with the appropriate color's Y-correction signal to produce a composite vertical correction signal. All six (6) correction signals are then amplified by the correction amplifiers and are sent to their respective yoke coils.

Serial Communication

The VDB uses two (2) separate, interrelated serial data communication systems to communicate with the SCB; the IIC bus, and a differential, synchronous data bus. The information transferred over the serial busses is indicated below (I = input to VDB, 0 = output from VDB). Also noted is whether the information is transferred over the IIC or the serial bus. A change in output data generates an interrupt pulse.

Model 330, 340SC and 370SC Service Manual 2-37

Chapter 2—Functional Descriptions

Bus

IIC

Serial Serial Serial Serial Serial Serial Serial Serial

Table 2-8

I/O

VDB Serial Bus Information

Information

Front/Rear convergence

indication

Description

TTL level that indicates whether the X-

convergence is in front screen mode (high) or rear screen (pulled low).

Serial data load

Command to the serial data receiver that the

incoming data is to be read.

I I I I I I I I

VCENTBLU VCENTGRN VCENTRED TRAPCORR LRPNCORR TBPNCORR HLINCORR

Commanded vertical height of picture. Commanded vertical position of blue raster. Commanded vertical position of green raster. Commanded vertical position of red raster. Commanded L/R keystone correction. Commanded L/R pincushion correction. Commanded T/B pincushion correction. Commanded overall horizontal linearity

correction.

General I/O

This section provides a comprehensive description of the inputs to and outputs from the VDB. 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 signal's direction is noted, with input referring to an input to the RTG, and output to an output from the VDB. (e.g. under 'Raster Timing Generator', 'Input'; /PCST refers to the signal /PCST that is an input to the VDB from the Raster Timing Generator). When test points are provided for the I/O they are noted.

Table 2-9

Input

IICCLK

RXCORR

RYCORR GXCORR GYCORR BXCORR BYCORR +SERCLK

-SERCLK

Vertical Deflection Board I/O Signals

System Controller Board

Description

IIC clock line. Unidirectional clock line for control of synchronous data

transfer over IIC data bus.

A 0-1 V signal from the bit-mapped memory on the SCB. 0.5V represents

no correction. This is a real time signal representing the X correction on

red. Similar to RXCORR. Similar to RXCORR. Similar to RXCORR. Similar to RXCORR. Similar to RXCORR. Serial data transfer clock (+). Unidirectional, differential clock line from

SCB to other circuit boards. Used for synchronous control of serial

communication over SERDATA data lines. Serial data transfer clock (-).

2-38 Model 330. 340SC, and 370SC Service Manual

+SERDATA Serial data transfer. Unidirectional, differential, synchronous serial data

Chapter 2—Functional Description

communication line. Used for transferring data from SCB to other

circuit boards. Uses SERCLK and IIC for control of receiver.

-SERDATA

Output

/IICINT

Serial data transfer.

System Controller Board

Description

IIC interrupt line. Signal line for slave boards to inform the SCB (master)

that there is data to be transferred. Master then polls slaves to

determine the source of the interrupt.

I/o

IICDATA

Description

IIC data line. Bi-directional serial line for synchronous data transfer

between SCB and other circuit boards. See detailed description for list

of signals transferred and data direction.

Raster Timing Generator

Inputs

/PCST

Description

Clock signal to start T/B pincushion, T/B Keystone, and horizontal

linearity correction.

Video Processor Board

Outputs

HPARAB VPARAB /SWEEPOK

Inputs

HSENSRED +15V indicates red horizontal flyback occurring at normal frequencies. HSENSBLU Similar to HSENSRED. HSENSGRN Similar to HSENSRED. HFDBCK

Description

Parabolic signal at horizontal frequency for dynamic focus. Parabolic signal at vertical frequency for dynamic focus. Low indicates that all six sweeps are occurring at normal frequencies.

Horizontal Deflection Board

Description

Voltage representing amount of horizontal scan drive. Used for modifying

amount of side pincushion and keystone when changing horizontal

frequency.

WIDTH

Positive DC voltage representing commanded width of the raster. Used for

generation of horizontal linearity ramp and T/B pincushion correction

waveform.

VERTDR HLINR TBKEYCOR Voltage representing commanded top and bottom keystone correction.

Pulse signal at vertical frequency from the vertical oscillator on the HDB. Voltage representing commanded horizontal linearity correction.

Model 330, 340SC and 370SC Service Manual 2-39

Chapter 2—Functional Descriptions

Outputs

FLRCLING

Description

Low signal generated from jumper on connector J400 indicates non-

inverted operation.

GEOCORR

Outputs

+RVERTYK Supply line to the main vertical deflection coil (red) after going through

Output from L/R pincushion and keystone correction circuits.

Main Vertical Deflection Coils

Description

FLRCLING jumper plug.

-RVERTYK

Return from main vertical deflection coil (red) after going through

FLRCLING jumper plug.

+GVERTYK Similar to +RVERTYK.

-GVERTYK Similar to -RVERTYK. +BVERTYK Similar to +RVERTYK.

-BVERTYK

Outputs

+RXCORR

-RXCORR +RYCORR

-RYCORR +GXCORR

-GXCORR +GYCORR

-GYCORR +BXCORR

-BXCORR +BYCORR

-BYCORR

Inputs

+24V +15V

-15V +5V GND

Similar to -RVERTYK.

Correction Coils

Description

Supply to the red X correction coil. Return from the red X correction coil. Similar to +RXCORR. Similar to -RXCORR. Similar to +RXCORR. Similar to -RXCORR. Similar to +RXCORR. Similar to -RXCORR. Similar to +RXCORR. Similar to -RXCORR. Similar to +RXCORR. Similar to -RXCORR.

System Power Supplies

Description

Power to vertical deflection. Power for analog portions of VDB. Power for analog portions of VDB. Power for digital devices on VDB. Return for power on VDB.

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Chapter 2—Functional Description

Interlocks and Shutdowns

Input

HSENSRED - Used to shut down the CRT beams in the event of horizontal sweep failure.

HSENSGRN - Identical to HSENSERED. HSENSBLU - Identical to HSENSERED.

Output

/SWEEPOK

Indicates whether or not all sweeps are occurring at or above a minimum frequency. Used on the VPB to turn off the signal in the event of loss of sweep.

Internal

None

Model 330, 340SC and 370SC Service Manual 2-41

Chapter 2—Functional Descriptions

Figure 2-14

Video Generation Block Diagram. This diagram provides an overall view of how the image is produced. Separate

sections of this chapter detail the individual PCBs.

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Chapter 2—Functional Description

Video Processor Board P/N 104672 (VPB)

The Video Processor Board (VPB) plugs into the electronics card cage. It is the rear-most card in the card cage. The VPB is the only card in the card cage that is held in by fasteners. There are four screws that tie the input tray to the rear panel of the card cage. The input tray is an aluminum panel that attaches to the VPB input BNC connectors. The input tray is a separate assembly and is not included with the VPB when a new or repaired board is shipped.

The following functions are provided by the VPB:

Image and sync signal input. Image and sync signal multiplexing. Sync signal stripping. Brightness and contrast control. CRT protection logic. Internal and external display multiplexing. Image signal gamma correction. LCLV uniformity correction. LCLV bias. Dynamic focus signal modification.

The block diagram (Figure 2-15) description, along with the I/O description in the following section, provide information to perform module-level troubleshooting.

Model 330, 340SC and 370SC Service Manual 2-43

Chapter 2—Functional Descriptions

Figure 2-15

Video Processor Board, Block Diagram

Decoder

The optional decoder is a daughter board installed on the VPB. Since the VPB can only operate on an RGB/sync signal, use of the decoder is necessary in order for the projector to use a composite signal. The decoder takes a composite (NTSC, PAL, or SECAM) or S-Vid input and converts it into an RGB Sync signal for

2-44 Model 330. 340SC, and 370SC Service Manual

Chapter 2—Functional Description

further use in the Video Processor Board. The IIC bus is used by the decoder to select either Channel 3 (NTSC) or Channel 4 (S-Vid). The two (2) signals are multiplexed together on the decoder board for export to the Video/Sync Mux.

Video/Sync Mux

The Video/Sync Mux selects one (1) of three (3) external inputs (RGB1, RGB2, or Decoder) for use as the source for Image display and sync signals. The two (2) external RGB Sync signals are selected by choosing RGB1 or RGB2 in the C

HANNEL LIST

composite input) or SVHS (for the S-Vid input) from the same C

under the C

HANNEL MENU

. Selecting either CVID (for the

HANNEL LIST

uses the input from the decoder. The input to be used is selected by the System Controller Board via the IIC bus. A green LED on the input panel is lit to indicate which input is selected. The RGB image inputs are AC coupled while the sync and decoder inputs are DC coupled. All inputs have a 75 ohm input impedance.

V & H Sync Strip

The vertical and horizontal sync signals are taken from the Video/Sync Mux and individually peak and trough detected then pulse shaped to provide a TTL-level signal representing the HSYNC and the VSYNC. Those signals are then sent out to the RTG as the signals HSYNC and VSYNC and can be monitored on TP 14 and 15 respectively.

SG Sync Strip

The SG Sync Strip circuit looks at the green image signal between the video MUX and the Brightness and Contrast Amp and sends the signal through a buffer then peak detects the signal. The peak-detected signal then is compared with a reference voltage to discriminate the sync signal from the video. The stripped sync signal is then pulse shaped to provide a TTL representation of the composite sync signal. The signal is sent out to the RTG as SGSYNC and can be probed at TP 13.

B, G, and R Brightness and Contrast Amplifiers

Each color of video (R, G, and B) uses an identical circuit. The Brightness and Contrast amplifier serves to adjust the black and white levels of the external video and also protects the CRT from excessive beam current by taking the beam current signal from the Video Output Amp and comparing it with a reference. If the beam current exceeds 1mA, the contrast command voltage is reduced to a level that brings the CRT beam current back within bounds.

The Brightness and Contrast amplifier takes the contrast command signal after the beam current limit circuit, and uses it to set the gain of the amplifier for contrast control. Contrast is controlled by the SCB via the IIC interface. The operator controls contrast level by pressing the C arrows on the remote control. Green is a master and will control all three (3) colors together. R and B are independent.

button and using the up and down

ONT

Model 330, 340SC and 370SC Service Manual 2-45

Chapter 2—Functional Descriptions

Adding a DC offset to the output of the amplifier controls brightness. The brightness is controlled by the SCB via the IIC interface. The operator controls contrast level by pressing the B the remote control. All three (3) colors are controlled together. During the DC Restore interval when the BPCP pulse (measured at TP 10) is high, the output of this amp is set to the nominal DC level.

On-Screen Switch

In the on-screen switch, the external video signal is multiplexed, in real time, with internal video signals. The internal video signals used are full brightness, black, or gray-scale/pyramid for a total of four (4) different signals that are multiplexed at each point on the screen. The real-time multiplexing is used for the generation of overlays and test patterns and is controlled by the switch logic. The output of the on-screen switch can be monitored by test points TP5 (Red), TP6 (Green), and TP7 (Blue).

Gamma Correction

button and using the up and down arrows on

RIGHT

After the On-Screen Switch the signal goes to the Gamma Correction section. Gamma Correction is a non-linear gain stage that accounts for the non-linearities of the ILA® Assemblies as well as for the CRT to produce a linear gray-scale on the screen for a linear gray-scale input.

Switch Logic and Vi deo Enable

This section controls the overlays and test patterns on the screen as well as providing protective functions.

Protection of the CRTs is accomplished by sensing dangerous conditions and initiating protective functions. There are three (3) conditions that the projector considers dangerous to the CRTs that are addressed in this circuit. Those three (3) conditions are loss of sweep (any of the six), defective video amp, and loss of power to the VPB.

When a loss of sweep occurs, the /SWEEPOK signal is released by the VDB and is pulled high by the VPB. This initiates two (2) protective functions. First (1st) is that the video signal is immediately cut off. This is the fastest way to reduce the CRT beam current to prevent CRT damage. It is also the least effective since even when there is no video signal to the video amp, there can still be beam current due to a high G2 or other causes. Therefore, a second (2nd) function is initiated when /SWEEPOK goes high. The enable signal to the video amps, /RENABLE, /GENABLE, and /BENABLE is released by the VPB (all three [3] regardless of which sweep is lost) and pulled high by the VAB. When this happens, it signals the VAB to remove some of the bias voltage from its CRT. This further reduces the possibility that there will be any beam current present during loss of sweep and although more effective than removing video signal, it takes more time.

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A defective video amp is detected by the state of the /RVIDOK, /GVIDOK, and /BVIDOK signals arriving from the VABs. A loss of +5V power to the VPB is detected by observing it internally to this circuit. When any one of the VIDOK signals goes high or a loss of +5V is detected, action will be taken to shut down all three (3) CRTs.

Loss of +5V or defective VAB can potentially be more serious than loss of sweep. Therefore, when one (1) of these conditions occurs, the same action will be taken as for loss of sweep with the additional action of shutting down the HVPS. This is done by releasing the /HVEN line allowing the HVPS to pull it high. Turning off the HVPS is the most effective way of protecting the CRT but is also slowest— explaining why other actions are taken in conjunction.

Switch logic is the portion of the circuit that controls what is seen on the screen at any point at a given time. The SCB sends out signals as the raster is scanned. These signals are outputs from the on-screen display bit-map. The signals controlling on-screen video are BONSCRN, RONSCRN, GONSCRN, VONSCRN, and VIDTEST. The signals are decoded in PALs on the VPB and result in signals that control the on-screen switch multiplexers to display the test patterns, text, and video.

Switch logic also takes in the signals from the RTG that control DC restore (DCRSTR) and blanking (VIDBLANK) and distributes them throughout the VPB and out to the VAB as the signals CLAMP and BLANKING.

RGB Sensitivity and Threshold Amplifier

Each color of video (R, G, and B) uses an identical circuit. The video signal is taken from the output of the gamma correction section,

amplified, and sent off the VPB to the VAB via signals RVOUT (TP1), GVOUT (TP2), and BVOUT (TP3).

The Threshold correction adds an offset to the signal in similar fashion to that of the brightness control in the Brightness and Contrast Amp. The difference is that the Threshold correction is, in general, not a pure DC signal, nor does the beam current limit circuit affect it. Rather, it is a varying signal generated by the System Controller Board in real time representing the correction necessary to account for turn-on-point variations across the ILA® Assemblies. The signals from the SCB are RTHRESH, GTHRESH, and BTHRESH. Also, when the clamp pulse signals that it is time to do DC restore, the /BPCP signal removes the threshold correction so that it will be reapplied after DC restore.

Sensitivity correction is applied by varying the gain of the amplifier. Like threshold correction, the sensitivity correction signal that controls the gain is not, in general, pure DC nor affected by beam current limit. It is a varying signal generated by the System Controller Board in real time representing the correction necessary to account for sensitivity variations across the ILA® Assemblies. The signals for sensitivity correction from the SCB are RSENS, GSENS, and BSENS.

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Video signal cutoff is accomplished by pulling blanking to zero.

ILA® Bias

ILA® Assembly biasing is accomplished by generating a pseudo-square-wave

with frequency set by the operator. The SCB sends the information on bias frequency via the IIC interface to the VPB. The operator can control the frequency over a range of from 1.5KHz to 3.0KHz. Selecting ILA BIAS FREQ from the ILA SETUP menu under the MAIN MENU controls the frequency. The bias square wave is phase locked to the vertical sync to prevent any moving artifacts from occurring on the screen due to bias.

The bias square wave is passed through an amplifier whose gain is set by the operator via the SCB to vary the bias. This square wave is then turned into a differential output in order to eliminate DC going to the ILA® Assemblies. The outputs can be monitored at TP11 and 12 (RED), 1 and 14 (GRN), and 15 and 16 (BLU). Selecting BIAS W/O VIDEO from the ILA SETUP MENU under the Main Menu controls the bias level for each individual color. The up and down arrows are then used to vary the bias level.

BUS

IIC IIC IIC IIC IIC IIC

IIC

Dynamic Focus Amplifier

The vertical focus amplifier takes the VPARAB signal from the VDB, amplifies it and sends it out to the HVPS as the signal VDFOCUS for vertical dynamic focus. The HPARAB signal, from the VDB, is multiplied by the VPARAB signal, amplified, and also sent out to the HVPS as the signal HDFOCUS for horizontal dynamic focus.

Serial Communication

The VPB uses two (2) separate, interrelated serial data communication systems to communicate with the SCB; the IIC bus, and a differential, synchronous data bus. The information transferred over the serial busses is indicated below (I = input to VPB, O = output from VPB). Also noted is whether the information is transferred over the IIC or the serial bus. A change in output data generates an interrupt pulse.

Table 2-10

I/O

I I I I I I

VPB Serial BUS Information

Information

RENABLE GENABLE BENABLE CH1SEL CH2SEL

ILA® bias freq Information for setting bias frequency to ILA

Signal to cut off red. Signal to cut off green. Signal to cut off blue. Selects RGB1 as input. Selects RGB2 as input.

Description

Assembly.

SLOAD

Command to the serial data receiver that the

incoming data is to be read.

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IIC IIC IIC

BUS

Serial I Serial I Serial I Serial I Serial I Serial I Serial I

I/O

O O O

VIDOK SWEEPOK BEAMDET

Information

REDBIAS GRNBIAS BLUBIAS RCONT GCONT BCONT BRIGHT

Tells SCB that no VABs are reporting problems. Tells SCB that all sweeps are operating. Tells SCB that beam current limiting is occurring.

Description

Commanded amplitude of red LCLV bias. Commanded amplitude of green LCLV bias. Commanded amplitude of blue LCLV bias. Commanded red contrast. Commanded green contrast. Commanded blue contrast. Commanded brightness level.

General I/O

This section provides a comprehensive description of the inputs to and outputs from the VPB. 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 signal's direction is noted, with input referring to an input to the RTG, and output to an output from the VPB. (e.g.: under Raster Timing Generator 'Input'; VSYNC refers to the signal VSYNC that is an input to the VPB from the Raster Timing Generator). When test points are provided for the I/O they are noted.

Table 2-11. Video Processor Board I/O Signals

System Controller Board

Input

IICCLK

Description

IIC clock line. Unidirectional clock line for control of

synchronous data transfer over IIC data bus.

BONSCRN

Along with RONSCRN, GONSCRN, VONSCRN,

VIDBLANK, and DCRSTR (the later two on from the RTG board) determines whether there is full brightness, black, gray-scale, or external video presented in blue at a

given point on the screen. RONSCRN GONSCRN VONSCRN VIDTEST

Similar to BONSCRN. Similar to BONSCRN. Determines if internal test patterns will be shown. Internal gray-scale video input information. Real time data 0V

to 1V. RSENS

Sensitivity (Z-axis gain) correction information for red. Real

time data at 0V to 1V. GSENS BSENS

Similar to RSENS. Similar to RSENS.

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RTHRESH

Threshold (Z-axis offset) correction information for red. Real

time data at 0V to 1V. GTHRESH BTHRESH +SERCLK

Similar to RTHRESH. Similar to RTHRESH. Serial data transfer clock (+). Unidirectional, differential clock

line from SCB to other circuit boards. Used for

synchronous control of serial communication over

SERDATA data lines.

-SERCLK +SERDATA

Serial data transfer clock (-). Serial data transfer. Unidirectional, differential, synchronous

serial data communication line. Used for transferring data

from SCB to other circuit boards. Uses SERCLK and IIC

for control of receiver.

-SERDATA

Outputs

/IICINT

I/O IICDATA

Serial data transfer.

System Controller Board

Description

Interrupt used to tell the SCB that the VPB has data to report.

Description IIC data line. Bi-directional serial line for synchronous data

transfer between SCB and other circuit boards. See

detailed description for list of signals transferred and data

direction.

Raster Timing Generator

Inputs

VIDBLANK

Description

Along with RONSCRN, GONSCRN, BONSCRN, and

VONSCRN from the SCB, and DCRSTR, determines

whether there is full brightness, black, gray-scale, or

external video presented at a given point on the screen. DCRSTR

Along with RONSCRN, GONSCRN, BONSCRN,

VONSCRN, from the SCB, and VIDBLANK, determines

whether there is full brightness, black, gray-scale, or

external video presented at a given point on the screen.

Outputs

SGSYNC

Description

Stripped Green Sync. The composite sync signal stripped from

the green channel

(if it exists) (TP13). HSYNC

Horizontal Sync. This can be either just the horizontal sync, in

which case there will be a separate vertical sync, or

HSYNC can be a composite sync. (TP14) VSYNC

Vertical Sync. This cannot be a composite sync signal. (TP15)

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Vertical Deflection Board

Inputs

VPARAB

Description

A periodic, positive-going, parabolic waveform with the

vertical scan frequency, used for dynamic focus.

HPARAB

A periodic, positive-going, waveform with the horizontal scan

frequency, used for dynamic focus.

/SWEEPOK

A TTL DC level signal indicating that, when low, indicates all

flybacks are occurring at or above a minimum frequency.

Video Amplifier Board

Inputs

RBEAM

Description

Voltage signal proportional to cathode current averaged over

several horizontal lines, in the red CRT. Voltage level is

+1mV/uA. GBEAM BBEAM /RVIDOK

Similar to RBEAM. Similar to RBEAM. Open collector signal indicating the health of the red +100V

cathode supply. /GVIDOK /BVIDOK

Outputs

BLANKING Pulse signal output that is a buffered replica of the VIDBLANK input

Description

Similar to /RVIDOK. Similar to /RVIDOK.

Video Amplifier Board

from the SCB. Indicates the commanded blanking interval during the scan.

/BENABLE Logical connection of video amp, sweep, and power health

indications. TTL level output. /RENABLE Identical to /BENABLE. /GENABLE Identical to /BENABLE. RVOUT GVOUT BVOUT CLAMP

Red video output. 0V to 1V (TP1). Green video output. 0V to 1V (TP2). Blue video output. 0V to 1V (TP3). Pulse signal output that is a buffered replica of the SCRSTR input

from the SCB. Indicates the commanded timing and duration of

the DC restore.

External Video

Inputs

RVIDCH1 RVIDCH2 GVIDCH1 GVIDCH2

Description

Red video input to channel 1. Red video input to channel 2. Green video with optional composite sync signal input to channel 1. Green video with optional composite sync signal input to channel 2.

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BVIDCH1 BVIDCH2 HSYNCCH1 Horizontal or composite sync signal to channel 1. HSYNCCH2 Horizontal or composite sync signal to channel 2. VSYNCCH1 Vertical sync signal to channel 1. VSYNCCH2 Vertical sync signal to channel 2. COMPVID LUM CHROM RTN

Outputs

+RLCLV

Blue video input to channel 1. Blue video input signal to channel 2.

Composite video signal, pass through to decoder. Luminance signal for SVHS, pass through to decoder. Chrominance signal for SVHS, pass through to decoder. Return for SVHS; pass through to decoder.

Image Light Amplifiers

Description

One half (½) of the differential pair providing a distorted square

wave to the red ILA. (TP 21)

-RLCLV

One half (½) of the differential pair providing a distorted square

wave to the red ILA. (TP 20)

+GLCLV

-GLCLV +BLCLV

-BLCLV

Inputs

RED GREEN BLUE SYNC IICINT CH3SEL CH4SEL VERT

Outputs

SCLK SDATA IICCLK IICDATA COMPVID LUM CHROM RTN

Similar to +RLCLV. (TP 19) Similar to -RLCLV. (TP 18) Similar to +RLCLV. (TP 17) Similar to -RLCLV. (TP 16)

Decoder

Description

Red video signal from decoder. Green video signal from decoder. Blue video signal from decoder. Horizontal sync signal from decoder. Interrupt signal from decoder, pass through to SCB. Indicates to VPB that video input is composite. Indicates to VPB that video input is SVHS. Vertical sync signal from decoder.

Description

Single ended serial clock from serial communication bus to decoder. Single ended serial data from serial communication bus to decoder. IIC clock pass through to decoder. IIC data pass through to decoder. Composite video signal, pass through to decoder. Luminance signal for SVHS, pass through to decoder. Chrominance signal for SVHS, pass through to decoder. Return for SVHS; pass through to decoder.

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High Voltage Power Supply

Outputs

VDFOCUS HDFOCUS

Description

Parabolic waveform of vertical frequency. Parabolic waveform of horizontal frequency modulated by the

VDFOCUS waveform.

/HVEN

Enable signal for HVPS, used to shut down HVPS for CRT

protection.

System Power Supply

Inputs

+5V GND +15V

-15V GND (TP 0) Return from analog components.

Description

Power supply to digital components. Return from digital components. Power supply to analog components. Power supply to analog components.

Interlocks and Protection

Chapter 2—Functional Description

Input

/SWEEPOK

TTL high indicates that one or more of the sweeps, either horizontal or vertical is not at or above the minimum amplitude and frequency. This will cause a cutoff so that RVOUT, GVOUT, and BVOUT will be pulled low. Additionally, /RENABLE, /GENABLE, and /BENABLE will be pulled high resulting in shutdown of grid bias at the Video Output Boards. Also, the SWEEPOK status bit will be transmitted to the SCB.

RBEAM

Signal representing average red CRT beam current at 1mV/1uA. At greater than 0.7V, causes contrast and overlay intensity on all three colors to be reduced.

GBEAM

Similar to RBEAM.

BBEAM

Similar to RBEAM.

/RVIDOK

High indicates low voltage at the +100V supply on the red Video Output Board. This causes a low at the VIDOK status bit sent to the SCB over the IIC. The /HVEN signal is allowed to go high shutting down the HVPS. Additionally, a high cutoff signal is sent so RVOUT, GVOUT, and BVOUT will be pulled low. /RENABLE, /GENABLE, and /BENABLE are also pulled

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high resulting in shutdown of grid bias at the Video Amplifier Boards. Also, the SWEEPOK status bit will be transmitted as a low to the SCB.

/GVIDOK

Similar to /RVIDOK.

/BVIDOK

Similar to /RVIDOK.

Output

/HVEN

When either /RVIDOK, /GVIDOK, or /BVIDOK from the Video Amplifier Boards is pulled high, or the +5V power on the Video Processor Board goes low, /HVEN is pulled high. This results in the HVPS being disabled, thus shutting down high voltage to the CRTs.

/RENABLE

High will cause grid voltages at the VAB to be pulled low shutting off the red CRT beam. High will result from high on /RVIDOK, /GVIDOK, or /BVIDOK from the VAB, +5V power going down on the VPB, or /SWEEPOK being pulled high from the VDB.

/GENABLE

Similar to /RENABLE.

/BENABLE

Similar to /RENABLE.

Internal

None

Video Amplifier Board P/N 103567 or 103774 (VAB)

The Video Amplifier Board (VAB) is mounted on and plugs into the back of the CRT. There are three (3) VABs—one (1) on each CRT and each is entirely dedicated to servicing its respective CRT. The video amplifier boards are the last stage of the video chain and provide all electrical connection to the CRTs except for anode voltage and chassis bond.

The following functions are provided by the VPB:

Connection of all voltages to CRT. Amplification of video signal. Blanking. DC restore. Bias voltage control.

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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 2-16

Video 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.

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Beam Current Sense

The cathode current is sensed at the output of the video amplifier, then filtered and amplified so that the output is a 1mV/1uA signal averaged over several horizontal lines (the number of lines depending on the horizontal frequency). This current sense signal is then sent to the VPB as the signal BEAM.

DC Restore

The DC Restore function is accomplished on the Video Amplifier Board when commanded by the CLAMP signal from the VPB. When the CLAMP signal arrives, the video signal has the offset values (Brightness and Threshold) removed so that they will not be changed by the DC Restore circuit. The CLAMP signal causes the output voltage to be sampled and compared to a reference. The difference is sent to the input of the video amplifier to set the new black level for the duration of the next horizontal line.

Arc Protection

The Arc Protection Circuit functions to drain off any energy that arrives at the Video Output Amplifier board due to arcs on the cathode or grids. The arc energy is suppressed by sending it directly to the HVPS chassis via the Arc Ground terminal on the

board.

Blanking

The Blanking circuit operates by using the BLANKING signal from the VPB. The BLANKING signal causes an amplifier to drive an AC coupled pulldown of GRID1. G1 voltage is normally -81V but will be pulled down to -111V during the blanking interval. The cathode voltage is unaffected by blanking.

Enable Circuit

The Enable circuit is controlled by the /ENABLE signal from the VPB. The /ENABLE signal, when pulled high, causes both GRID1 and GRID2 to be pulled low: G1 is pulled from nominal -81V to the disabled value of -200V, G2 is pulled from its usual value of between +800V to +1200V to its disabled value of +15V.

Focus

The FOCUS voltage is a pass through from the HVPS to the CRT. It is not in any way modified by the VOB.

Filament Supply

For the CRT Filament supply, 6.3Vdc from the System PS is simply filtered and sent to the CRT.

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General 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 signal's 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 noted.

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Table 2-11

Input

VIN

Video Amplifier Board I/O Signals

Video Processor Board

Description

COAX input from VPB via the backplane. Video signal of 1V peak-

to-peak maximum.

/ENABLE

TTL level DC signal which controls grid voltages. High causes G2

to be pulled to +15V and G1 to be pulled to -200V shutting off the CRT beam.

CLAMP

TTL level pulse controlling DC restore. Restores black level of

cathode voltage to +84V.

BLANKING TTL level signal controlling video blanking. Pulls G1 to 30V below

normal voltage to turn off beam.

Outputs

BEAM

/VIDOK

Description

Positive voltage indicating beam current averaged over several lines. 1mV = 1uA of beam current. Indicates health of the +100V cathode supply. Open collector output

opens when supply goes below 64V.

CRTs

Output

FOCUS GRID1

Description

Focus voltage directly from HVPS to CRT. Regulated DC voltage to Grid1. Nominally -81V during normal

operation. During blanking, G1 is -111V, and during /ENABLE high, G1 is -200V.

GRID2

Variable DC voltage to Grid2. G2 voltage is normally 800 to

1200V. When /ENABLE high, G2 is 15V.

CATHODE

DC black level modulated by video signal. DC black level is +84V.

Modulation is negative-going 75V peak-to-peak max. FILAMENT FILAMENT

6.3V filtered goes to filament. Return from filament supply.

RTN

High Voltage Power Supply

Inputs

-200V FOCUS G2

Description

Power supply to Grid1 regulator. Pass-through from HVPS to CRT. +100V to +1400V supply to Grid2. Passes through G2 pulldown

circuit for protection.

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System Power Supply

Inputs

+107V +6.3V +15V

-15V GND ARC GND

Description

Power supply to cathode drive amplifier. Power supply to filament. Power for analog components. Power for analog components. Return for power supplies. Low impedance return path to HVPS for arc currents.

System Controller Board P/N 104668 (SCB)

The system controller board plugs into the electronics card cage. It is the middle board in the card cage (third from the front).

The following functions are provided by the SCB:

Operator Interface:

IR Interface. RS232 Interface. On-Screen Menus. Dot Matrix Display.

Inter Board Communications and Control:

IIC Bus (Overall system control). Serial Bus. Power Supply Interface.

Projector operation:

Direct operation of the projector by issuing commands based on external directives and internal information.

Contains program and working memories.

Generate Overlays:

Digital Test Patterns. Gray-Scale.

Provide Convergence Correction Outputs:

X and Y Axis Correction. Sensitivity and Threshold Correction.

The block diagram (see Figure 2-17) description, along with the I/O description in the section following, provide information to perform module-level troubleshooting.

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General Functional Description

The system controller board receives external commands, interprets those commands, and issues internal commands to control the operation of the arc lamp, light valves, raster generation, video signal amplifiers, and other components necessary for projector operation.

The SCB receives commands from the outside world via the IR or RS232 interface. Output communication is accomplished via the RS232, the dot matrix display, and the CRT display.

Control of raster generation by the SCB is limited to primarily controlling geometric and convergence correction while most other raster functions are under local hardware control.

Video signal control involves choosing which video input to use, whether or not to insert overlays, and setting gain and offset values.

The SCB also takes in information on raster and video status from other circuit boards and generates control signals and displays based on that information.

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Figure 2-17

System Controller Board, Block Diagram

CPU

The central processor (CPU) is a Motorola MC68302 embedded controller and is the main controlling component of the projector.

Operation of the CPU is controlled by the program instructions written in the Program Memory. The program memory consists of two (2) UV erasable EPROMs (U24 and U63) loaded with the appropriate software for the projector, mounted in sockets for ease of updating the software. The EPROMs, being nonvolatile, will maintain their integrity under all operational conditions. Upgrading the program memory is simply a matter of replacing the EPROMs with the newer version.

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As the CPU processes information, it is stored in the Working and Compressed Memory. This includes all temporary storage as well as the channel data that the operator sets while ‘tweeking up’ the projector.

All communication, both input and output, for internal signals and operator interface, is directly controlled by the processor. On-screen messages are generated and written to the Overlay Memory which serves as a video memory for controlling the on-screen display. RS-232 commands are received and sent via the RS-232 interface. IR communications are only received by the projector. No capability for transmitting IR is provided in the projector. The CPU communicates directly with the IR interface to receive commands. The CPU sends status and error codes to the LED interface for display on the dot-matrix display on the rear of the projector. Internal communication is accomplished by the processor sending data via the IIC interface and the serial data interface.

The CPU also directs the operation of the DSP.

Working and Compressed Memory

The Working and Compressed Memory (WCM) consists of four (4) SRAMs, mounted in sockets that provide battery backup which in turn provides the ability to maintain all projector settings even when the projector loses power for extended periods. Although not covered separately by warranty, the battery should be able to maintain the stored data for over one (1) year with no power applied to the projector. With power applied, the battery should remain viable for up to ten (10) years.

WCM is used as working memory for the CPU. All temporary storage of working data during routine CPU operations is done in the WCM. Additionally, the channel data is stored in WCM. There are 29 channels of data that can be stored in the projector. Channel data is all of the information that is stored that is specific to a particular projector channel. For example, the Position settings for R, G, and B, the ILA frequency, X convergence correction, Sensitivity correction, etc. As well as the channel data, global data is also stored in the WCM. This includes anything that is not channel specific such as auto-select groups, timers, and status logs. As long as the battery backup remains viable or power is applied to the projector, the WCM will remain intact. However, if data is corrupted for any reason, such as removing one (1) of the four (4) memory chips or a battery losing power while the projector is not plugged in, all of the data in the WCM will be lost. For this reason, it is always a good idea to back up the channel data to an external data storage medium.

Expanded Memory

The Expanded Memory (EXM) is composed of twelve (12) memories. Each of these memories stores information that will be used to correct the raster for both shading and convergence.

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The digital information that is to be used for raster correction is stored in bit-map form. The bit-map is 96 fields (out of 112) wide by the number of horizontal lines in a frame wide. Each address in the EXM corresponds to a small section of one (1) line on the screen.

As the raster is scanned, the EXM is being read out so that during the time that each line of the raster is being scanned, 96 memory locations are being read. In this way, each area of the raster can be accurately corrected.

Since there are twelve (12) functions to be corrected (R, G, and B for each of X registration, Y registration, Threshold, and Sensitivity), each memory corresponds to one correction function. All twelve (12) memories are read out simultaneously, one (1) address at a time, to provide the correction required for the raster.

Correction Address Generator

The Correction Address Generator is used to address the EXM during both load and readout. During the loading time, when the DSP is writing to the EXM, the DSP controls the address generator, both setup and timing. During the time when writing is not occurring, the memory is being read. At that time, the address generator is set up by the DSP, but it’s timing signals come from the RTG to synchronize it with raster generation.

During the read times, the address generator uses the /CORRSTRT and /MAPST signals from the RTG as timing signals. The timing clock used is the /HX112 signal. Thus, the address generator generates addresses at the rate of 112 times the horizontal frequency. It does this for 96 clock pulses, then stops. After the next /CORRSTRT signal, it generates another 96 addresses. This repeats for each line in the raster. The starting address is timed by the /MAPST signal. When that comes along, it indicates the top of the raster is beginning so the address generator should begin counting at the beginning.

During writing times, as the DSP generates data, it causes the address generator to increment to the proper address to be loaded.

DACs

The Digital to Analog Converters are used to convert the digital data stored in the EXMs to analog form for use by the correction amplifiers. There are twelve (12) DACs, one (1) for each memory. Six (6) of the DACs are for X-Y registration and send their outputs to the VDB. The other six (6) DACs are for shading (Threshold and Sensitivity) and send their outputs to the VPB. The data from the DACs is real time data that corrects the raster as it is scanned.

DSP

The Digital Signal Processor is a slave processor that operates under the control of the CPU. The DSP does the processing that converts the raw convergence and shading numbers that the operator inputs, into the smooth correction data that

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drives the correction amplifiers. The raw (compressed) data is stored in the WCM while the smooth (expanded) data is stored in the EXM.

When a channel change occurs in the projector, the compressed correction data that is stored in the WCM is interpolated by the DSP into the expanded form that is stored in the Expanded Memory.

The compressed data is stored in the WCM in a 33X33 matrix of values representing the desired correction over the whole screen. For each channel, there are twelve (12) of these matrices stored in the WCM; one (1) for each color of each function (R, G, and B for each of X registration, Y registration, Threshold, and Sensitivity).

Overlay Memory

All display that does not originate from the external source is called Overlay and includes on-screen text and test patterns. In order to produce overlays, a bit-map must be generated that can be read out as the raster is being produced by the projector’s deflection circuits. This bit-map tells what to show on the screen at any point at any time. The CPU generates the bit-map and stores it in the overlay memory for readout during raster scanning. When there is no overlay to be presented, there is nothing but external video to show. That information is also stored in the overlay memory.

The Overlay Memory is composed of two SRAMs. They are not battery backed since they store no data that must be held while the projector is not in operation. The Overlay Memory is used to store the bit-mapped information that describes the overlay pattern that is seen on the faces of the CRTs, hence on the screen. The overlay bit-map is 192 fields wide (out of 224) by the total number of raster lines. Each of these memory locations stores information that determines what will be displayed at that particular point on the screen. These choices are full bright or black for each color individually, gray scale for all three (3) colors together, or external video for all three (3) colors.

Overlay Address Generator

The Overlay Address Generator is used to address the overlay memory in a manner similar to how the correction address generator addresses the EXM during both load and readout.

The CPU controls the operation of the Overlay Address Generator while writing to the overlay memory. During the read times, as with the correction generator, the overlay address generator uses the /CORRSTRT and /MAPST signals from the RTG as timing signals. However, the timing clock used is the /HX224 signal. This is because the generator must run at 224 times the H frequency in order to be able to generate the 192 addresses required for each line of overlay.

The addresses are generated for 192 clock pulses then the generator pauses. After the next /CORRSTRT signal, it generates another 192 addresses. This repeats for

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each line in the raster. The starting address is timed by the /MAPST signal. When that comes along, it indicates the top of the raster is beginning so the address generator should begin counting at the beginning.

Overlay Interface

The Overlay Interface takes the raw data out of the Overlay Memory and sends formatted information to the VPB for generating the desired displays. Some of the data is simply buffered and sent along. That data is the information regarding the full brightness and external video that produces everything but greyscale and dots. The greyscale, dot, and pyramid patterns must first be decoded by a D to A. After conversion to analog and appropriate filtering, the information is sent out to the VPB as the VIDTEST signal.

LED Display Buffers and Logic

The LED dot matrix display is located on the rear of the projector just under the video and sync input connectors. In that location, it is not physically located on the SCB but it is directly controlled by the CPU with connection via the backplane.

The Dot Matrix Display is used for displaying operational and error codes. These codes will assist in troubleshooting and verifying proper operation. The Dot Matrix Display receives its data from the CPU via the display buffer.

RS232 Interface

The RS232 Interface is a bi-directional communications port. The interface protocol is RS232 with two (2) ports; one (1) port being fully functional with the other having more limited use.

The Terminal In port is the fully functional port. It is used for communicating with the projector using a VT100 or similar terminal emulator. The terminal allows accessing all functions available on the projector. In addition, using the terminal provides the user with continuously updated status data. The bidirectional port allows third-party controllers to be used to control the projector using ASCII character control codes.

The Terminal Out port is also RS232 but has limited functionality. It is used primarily for attaching a switcher to the projector to allow for smoother switching of sources.

IR Interface

The IR Interface is a receive-only interface. There is no capability to transmit information out of the projector over the IR interface. The user must depend on the on-screen information and LED Dot Matrix displays to verify operation of the projector.

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Chapter 2—Functional Descriptions

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 away.

The IR receivers are not located on the SCB but are directly controlled by the CPU and are connected via the backplane.

IIC Interface

The IIC Interface is used to transfer operating data to the circuit boards. IIC is a protocol for a chipset made by Phillips. It is a bi-directional serial communications interface. The IIC uses three (3) lines for communications: a clock line (IICCLK), a data line (IICDATA), and an interrupt line (/IICINT). The SCB is the master when communicating over the IIC with the other circuit boards being slaves. The SCB sends information to another board by sending an address then data. When the circuit boards have information to communicate to the SCB, an interrupt is generated.

The SCB polls the boards to see who sent the interrupt. The SCB then reads the information from the IIC bus.

One primary use of the IIC in the projector, in addition to its use as a data transfer device, is control of the differential serial communications bus.

Serial Interface

The Serial Interface is a differential communication bus used for transferring data quickly from the SCB to the other boards. It is unidirectional. In order for any board to receive a packet of data via the Serial Interface, it must first be commanded to receive that data by the IIC interface. Then the data is sent over the differential bus to the receiving board. Once a packet of data has been sent, the IIC must again be used to allow another packet to be received.

General I/O

This section describes the inputs to and outputs from the SCB. The I/O descriptions are arranged by the source/destination of the signal. The assemblies communicated with are the primary heading of each group of signals and are further subdivided into inputs and outputs. In each case, the signal's direction is noted, with input referring to an input to the SCB, and output to an output from the SCB. (e.g. under Raster Timing Generator; 'Input'; /MAPST refers to the signal /MAPST that is an input to the SCB from the Raster Timing Generator Board). Any test points provided are noted.

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Table 2-12

I/O

IICDATA

System Controller Board I/O Signals

Video Processor Board

Description

Data line for transferring the following information

(I = input, O = output). The input data are associated with an interrupt pulse.

Input

/IICINT

Output

IICCLK +SERCLK

-SERCLK +SERDATA Serial data transfer. Used to transfer the following command data:

I VIDOK I SWEEPOK I BEAMDET O BENABLE O GENABLE O RENABLE OCH1SEL OCH2SEL O SLOAD O VERTICAL FREQUENCY

Description

Interrupt used to tell the SCB that the VPB has data to report.

Video Processor Board

Description

Clock signal for IIC data bus. Serial data transfer clock. Serial data transfer clock.

REDBIAS, GRNBIAS, and BLUBIAS to control the bias on the three (3) ILA®s respectively, RCONT, GCONT, and BCONT to control the contrast for the three CRTs, and BRIGHT to control the brightness for all three CRTs.

-SERDATA BONSCRN

Serial data transfer. Output from the overlay interface used to turn blue overlay on and

off. RONSCRN GONSCRN VONSCRN

Similar to BONSCRN. Similar to BONSCRN. Output from overlay interface used to turn external video on and

off. VIDTEST RSENS GSENS BSENS RTHRESH GTHRESH BTHRESH

Video signal output for gray-scale. Real time data at 0V to 1V. Sensitivity output from the DAC at 0V to 1V with 140 ohm Zout. Similar to RSENS. Similar to RSENS. Threshold output from the DAC at 0V to 1V with 140 ohm . Similar to RTHRESH. Similar to RTHRESH.

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Raster Timing Generator

I/O

IICDATA

Description

Data line for transferring the following data (I = input, 0 =

output). The input data are associated with an interrupt pulse.

Input

/IICINT /FRAMEST

O Priority Select I /Sync Select I Internal Sync I Horizontal Count I /Phase Lock IINTI O Vertical Flyback Start Delay O Map Start Delay OL Blank OR Blank OU Blank OD Blank O/STBP O DC Restore Delay I Phase Count I Correction Delay I Pincushion Start Delay

Description

Interrupt used to tell the SCB that the RTG has data to report. Timing pulse Indicating the beginning of a frame. Used in the

SCB for counting vertical frequency. (TP5)

/MAPST

Signal used to start the correction and overlay address counters

during each vertical sweep. (TP12)

/Hx112

Clock pulse at 112 times the horizontal frequency. Used for

convergence and Z-axis correction map generation. (TP20)

/Hx224

Square wave signal 224 times the horizontal frequency for

overlay map generation, horizontal map correction start, left and right blanking, DC restore, and other timing functions. (TP23)

/FIELD1

TTL level indicating which field of an interlaced frame (Low if

non-interlaced. (TP8)

/CORRSTRT Signal used to start the convergence and overlay address

generators during each horizontal sweep. (TP4) INTI /VSYNC

Indicates when input source signal is interlaced. (TP2) Regenerated vertical sync signal, pulse-shaped to 3 horizontal

lines in width. (TP21)

Output

Description

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Chapter 2—Functional Description

SYSCLK IICCLK +SERCLK

-SERCLK +SERDATA Serial data transfer.

-SERDATA

I/O

IICDATA

4.05MHz clock signal Clock signal for the IIC data bus. Serial data transfer clock. Serial data transfer clock.

Serial data transfer.

Vertical Deflection Board

Description

Data line for transferring the following data (I = input, O =

output), the input data are associated with an interrupt pulse.

Input

/IICINT

Description

Interrupt used to tell the SCB that the VDB has data to

SLOAD

report.

Output

IICCLK +SERCLK

-SERCLK +SERDATA

Description

Clock signal for the IIC data bus. Serial data transfer clock. Serial data transfer clock. Serial data transfer. Used to transfer the following command

data: VH+, VH- to control the vertical amplitude (height) VCENTRED, VCENTGRN, VCENTBLU to control

vertical

centering of the red, green and blue rasters respectively; TRAPCORR to control keystone correction; LRPNCORR for left and right pincushion correction; TBPNCORR for top and bottom pincushion correction; HLINCORR for horizontal linearity correction.

-SERDATA RXCORR RYCORR GXCORR GYCORR BXCORR BYCORR

Serial data transfer. Horizontal correction output from DAC with 140 ohm Zout. Vertical correction output from DAC with 140 ohm Zout. Similar to RXCORR. Similar to RYCORR. Similar to RXCORR Similar to RYCORR.

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Horizontal Deflection Board

I/O

IICDATA

Input

/IICINT

Output

IICCLK +SERCLK

-SERCLK +SERDATA

Description

Data line for transferring the following data (I = input, O = output).

O Flyback Switch Select O Flyback Switch Pulse I Front/Rear indication I Floor/Ceiling Indication O Serial Data Load

Description

Interrupt that tells the SCB that the HDB has data to report.

Horizontal Deflection Board

Description

Clock signal for the IIC data bus. Serial data transfer clock. Serial data transfer clock. Serial data transfer. Used to transfer the following command data:

HPHASE to control the horizontal phase, HLINR to control the horizontal linearity, HCENTBLU, HCENTGRN, HCENTRED to control the horizontal centering of the blue, green and red rasters respectively, and WIDTH to control the horizontal width of all three rasters and for control of geometric correction.

-SERDATA

Inputs

+5.0V +5V STB +15V

-15V /LAMPLIT

Output

/LVPSNBL /FANENBL /ALENBL

Outputs

LEDDO-6 /LEDLT /LEDWR

Serial data transfer

Description

Power for digital components Power to CPU and peripherals Power for analog components Power for analog components Indicates normal operating voltage being supplied to Arc Lamp

Description

Low Voltage Power Supply Enable Signal to enable 24V Standby Power Enables Arc Lamp Power

Description

Data Lamp test Write

System Power Supply

Dot Matrix Status Display

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/LEDBL1 /LEDBLO

RS232 #1 RXD1 TXD1 /CTS1 /RTS1 DCD1 COMRTN

Input

/RIRIN /EXTIRIN EXTIRIN /FIRIN

Backplane Board p/n 100571

Brightness Brightness

RS-232 Interface Signals

RS232 #2 RXD2 TXD2 /CTS2 /RTS2

Description

Input from rear IR Receiver Differential input from IR Receiver Differential input from IR Receiver Input from front IR Receiver

Description Receive data Transmit data /Clear to send /Ready to send Carrier detect Return

IR Interface

The Backplane is a PCB that serves as an interconnecting point for the tethered and IR remotes, power supplies, CRTs, Yokes, ILA® assemblies, PCBs and external video. The Backplane does not modify signals in any way—it merely provides an interfacing point for most of the wiring in the projector in lieu of cabling. Refer to Figure 2-18 for a general idea of how the wiring is interconnected in the projector.

Tethered Remote or PC

ILA Biases

Video and Deflection Signals

ILAs

CRTs, Yokes, Video Amps

Optical

System Power Supply

High Voltage Power Supply

External Video

Signals

Power

Control

Backplane

Power

Control

PCBs

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Chapter 2—Functional Descriptions

Figure 2-18

2.7 Optical Section

The Optical section consists of the CRT Assembly, the Arc Lamp Assembly, and the Optical subassemblies, which provides the image to be viewed on the screen. The Optical Section filters, splits and directs the high intensity light to the three (3) separate (RGB) light channels. Figure 2-19 shows the video path from the CRT to the screen and the optical path from the Arc Lamp to the screen.

CRT Assembly

The image in the projector begins at the three (3) CRTs. The CRT Assembly is located beneath the main electronics card cage and contains three (3) sets of the following:

CRT tubes. CRT cooling assemblies. CRT Yokes. Yoke clamps.

Backplane Interface Block Diagram

Video Amplifier Boards.

Each CRT has a high resolution infrared beam and a high resolution phosphor screen. Fans mounted at the rear of the assembly cool the CRT Assembly. Procedures for adjusting the yokes and the width coils can be found in Section.3.2. A functional description of the Video Amplifier Boards is provided in Section 2.6.5.

Relay Lens

The relay lens picks up the CRT image from the face of the CRT and focuses the image to the ILA® assembly.

Image Light Amplifier (ILA®) Assembly

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 then phase modulated (altered) by the video signal from the input side of the ILA back out of the output side and then travels through the prism to be picked up by the projection lens.

assembly and then reflected

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 phase

modulated 90° to vertical by the Liquid Crystal layers into vertically polarized

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Chapter 2—Functional Description

light. 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.)

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Chapter 2—Functional Descriptions

CRT Image

CRT

CRT Image

Relay Lens

Focuses Image onto the ILA

High Intensity Light

Arc Lamp

Generates high intensity light beam

Cold Mirror

Filters infrared light

Combined Image and High Intensity Light=Bright Image

ILA

Image and High intensity Arc lamp light are combined at the ILA and reflected back toward prism

UV Filter and Condensing Lens

Filters out U.V. light. Condenses the light beam

Prism

Projection Lens

Prism horizontally polarizes the light and directs it to the ILA. Also passes reflect ed vertically polarized light coming from the ILA to the projection lens

Blue LightHigh Intensity

Blue dichroic reflects blue, passes green & red. Green dichroic reflects green, passes red.

Blue Dichroic Mirror

Green Dichroic Mirror

Red Dichroic Mirror

Down-steering mirrors steer light to correct prism.

Blue DownSteering Mirror

Green DownSteering Mirror

Red DownSteering Mirror

Screen

Green light to green prism

Red light to red prism

2-74

Figure 2-19

HJT Model 330, 340SC, and 370SC Service Manual

Optical Block Diagram

Chapter 2—Functional Description

Prism

The 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 phase modulated into a vertical plane by the input side

of the ILA

assembly and then reflected back toward 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 and into the projection lens.

Projection Lens

The projection lens picks up the high intensity image from the prism and transmits it to the projector screen. The projection lenses are individually mounted so they can be focused and aligned separately. The green lens is fixed horizontally and the red and blue lenses allow horizontal movement to align them with the green lens. Various focal lengths, (focal length = throw distance/screen width), are available for different sized rooms and screens.

Arc Lamp Assembly

The high intensity light from the Xenon Arc Lamp produces a “full screen” output of between 3,000 and 6,800 lumens, depending on the model of projector. The output from the arc lamp, along with the output from the ILA® Assemblies, produces the images on the screen.

NOTE:

lamp is covered with a safety glass plate and is mounted in a protective metal housing. This housing provides protection and ensures accurate alignment of the arc lamp optical axis with the projector housing by means of machined surfaces and precision alignment pins.

The Arc Lamp itself, a gas-filled device, maintains a relatively constant voltage. It, therefore becomes the voltage controlled device and the SPS Arc Lamp supply controls the current to the lamp. The constant voltage maintained by the lamp and the constant current provided by the SPS result in a constant power supplied to the Arc Lamp.

The arc lamp and reflector housing is never disassembled in the field. The arc lamp is replaced by exchanging the complete assembly.

The Arc Lamp Assembly also includes the Ignitor and its circuitry. The Ignitor circuit provides a momentary high voltage that excites the xenon gas inside the Arc Lamp. After the arc lamp is struck and turns on, it is maintained by a highcurrent, low-voltage power supply.

To protect equipment and personnel against explosion hazard, the arc

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Chapter 2—Functional Descriptions

Optical Subassemblies

Cold Mirror

The Cold Mirror lets most of the infrared light pass through and reflects the rest of the light toward the prism through an ultraviolet filter/condensing lens, dichroic mirrors and down-steering mirrors. The infrared light is absorbed in a series of fan-cooled screens.

hot!

Ultraviolet Filter and Condensing Lens

The arc lamp light beam reflected off the cold mirror passes through the Ultraviolet Filter/Condensing Lens that removes most of the Ultraviolet light and condenses the light beam. Therefore, most of the infrared and ultraviolet light is filtered out before the beam enters the more sensitive portions of the optics, leaving only the visible portion. Without these filters, the infrared light would overheat the prisms and the ILA® assemblies, and the ultraviolet light would damage the ILA® assemblies and be hazardous to personnel.

Dichroic Mirrors and Down-Steering Mirrors

The condensed light beam strikes the first dichroic mirror that is designed to pass red and green light but reflect blue light. The blue light is reflected to a downsteering mirror which reflects it again directly to the prism in the blue system. The red and green light travel on to the next dichroic mirror that passes the red light and reflects the green light to the down-steering mirror and prism in the green system. The red light travels on to the last Dichroic mirror which reflects the remaining red light to the last down-steering mirror and prism in the red system. Each of these three (3) light beams independently combines with the video image in their own (red, green or blue) color systems at the ILA® assemblies as described above.

CAUTION!

Cold mirrors absorb IR light and can get very

the use of a complex laser beam alignment fixture.

CAUTION!

Do not attempt to realign any mirrors. They require

2.8 Image Light Amplifier

A closer examination of the output side of the ILA® assembly as illustrated in Figure 2-20 helps in understanding its operation.

Visible light from the arc lamp passes through dichroic mirror assemblies and is then reflected into a prism assembly that polarizes the light horizontally. The

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Chapter 2—Functional Description

horizontally polarized light is sent through the liquid crystal layer of the ILA

assembly, reflected by a dielectric mirror surface, and then sent back through the liquid crystal layer on the way out of the ILA® assembly.

Figure 2-20

The polarized light is phase modulated, or rotated, up to 90º by the liquid crystal

The Hughes-JVC Image Light Amplifier

layer; 45º of rotation for the first pass through, and another 45º after being reflected by the internal mirror.

The axis of the polarized light is proportional to the brightness on the input side of the ILA® assembly. For example, when the photoconductor on the input side is not illuminated, the liquid crystal does not rotate the polarized light from the arc lamp. Conversely, when the input side is fully illuminated, the liquid crystal rotates the polarized light a full 90º from a horizontal direction to a vertical direction. Ninety-nine percent (99%) of the light energy entering the ILA

assembly is reflected.

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Chapter 2—Functional Descriptions

Figure 2-21

The phase modulated light exiting the ILA® assembly re-enters the prism

Simplified illustration of the Series 300 Projector optical path

assembly that, in this direction, passes vertically polarized light to the projection lens and onto the screen. Horizontally polarized light re-entering the prism assembly is rejected. Light that is not fully horizontally or vertically polarized will pass through the prism assembly in varying degrees of brightness.

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3.0 Service Adjustments

Contents

3.1 Service (Cover-Off) Power-On Sequence..................................................3-1

3.2 CRT Yoke Rotation....................................................................................3-3

3.3 Vertical Size Tracking................................................................................3-5

3.4 Vertical Linearity Tracking........................................................................3-6

3.5 Horizontal Size Tracking ...........................................................................3-7

3.6 ILA

3.7 CRT Mechanical Focus..............................................................................3-9

3.8 Electronic Focus.........................................................................................3-9

3.9 Jumper Settings..........................................................................................3-13

3.10 G2 Adjustment ...........................................................................................3-16

3.11 Arc Lamp Alignment and Focus................................................................3-18

3.12 Arc Lamp Current Adjustment...................................................................3-21

Bias Settings .....................................................................................3-8

Front/Rear Jumpers...................................................................................3-13

Inverted Vertical Jumpers .........................................................................3-15

Sensitivity/Threshold Offset......................................................................3-16

G2 Setting..................................................................................................3-16

Model 330 Arc Lamp Alignment and Focus.............................................3-18

Model 340SC and 370SC Arc Lamp Alignment and Focus.....................3-20

3.1 Service (Cover-Off) Power-On Sequence

Before applying power to the HJT Model 330, 340SC and 370SC Projector, verify that the projector is connected to the correct power source (refer to Table 0-1 in the Safety chapter). If there is any visible damage to any of the cables do not power on the projector until the damaged cable is replaced.

To turn on projector power:

1. If using a terminal or tethered remote control, connect one or the other to

the input jack marked "Terminal In" on the rear panel of the projector card cage.

2. Remove the rear cover from the projector.

CAUTION!

and the rear cover must be removed, be sure to set the power interlock switch (top right as shown in Photo 3-1) to the UP position immediately and turn the projector back on

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If the projector has been operating,

Chapter 3---Service Adjustments

with the remote. Then turn the projector power back off with the remote. This allows power to be reapplied to the fans to cool the arc lamp that remains very hot even after power is removed. During a normal power shutdown the fans continue to run for several minutes to cool the arc lamp.

3. Turn on the main circuit breaker (located on the bottom, right side of the

main power supply inside the projector in (see Figure 3-1). This switch turns on the +5V standby power supply for the main processor.

4. Replace the rear cover on the projector or set the power interlock switch,

on top of the system power supply, to the full UP position (see Figure 3-1).

WARNING!!!

be careful not to touch any open parts of the projector. Be particularly careful of any high voltage wires (large, red wires) which although heavily insulated could still cause severe electrical shock if the insulation is pinched or damaged. or directly at any of the projection lens light paths-the light intensity is strong enough to cause injury to eyes.

NEVER

With the cover off the projector,

look into the Xenon Arc Lamp light path

NOTE:

active display should now appear on the LCD or screen. This is the Standby Power mode. The projector is now ready for a power "ON" command.

Figure 3-1

If using a tethered remote or a terminal for projector control, an

Power Interlock Switch and Main Circuit Breaker.

Set power interlock switch to full UP position to power the projector with the rear cover removed.

Main AC Circuit Breaker

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Chapter 3---Service Adjustments

1. Press the Power ON key to turn on the projector (press both power keys

simultaneously if using the tethered remote). The Ignitor circuit will ignite the arc lamp and power will be applied to the electronics system.

NOTE:

To power up the electronics only, type CTRL-E. To power up the lamp only, type CTRL-L. These are toggle commands; repeated issuance of the commands toggles these power sources on and off. The lamp and electronics cannot be powered up separately with the remote controls.

If using a terminal or PC, turn full power on by typing CTRL-P.

3.2 CRT Yoke Rotation

The CRT deflection yokes are factory set. If the CRT image is not level, adjust the individual CRT deflection yoke as required (see Figure 3-1).

WARNING!!!

when performing the yoke rotation, always wear ANSI/ASTM 10,000 volt rated safety gloves for protection from high yoke voltages present. Ensure the gloves are not cracked!

To adjust the deflection yokes:

2. Press T

3. Cutoff R and B and view G.

2 to display the White X-hatch pattern.

EST

To prevent possible electrical shock

4. Remove the rear projector cover (see Section 4.2).

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Chapter 3---Service Adjustments

Figure 3-2

5. Remove the 2.5mm Allen screw holding the electronics module in place

6. While observing the center horizontal line on the grid pattern, rotate the

7. View R.

View of the CRT Assembly showing deflection yokes, width coils, CRTs

and Video Amplifiers.

and tilt the electronics module (see CAUTION following) back to expose the CRT necks and yoke.

CAUTION!

rear electronics jacks or the plugs could be badly damaged when the electronics module is tilted back.

green CRT deflection yoke, (the green CRT is in the middle), to achieve a level image at the center of the screen (if necessary, loosen the yoke clamp slightly to adjust it).

NOTE:

while rotating it to ensure the yoke remains properly positioned on the CRT.

Whenever adjusting the CRT yoke, push forward on the yoke

Remove anything plugged into the

8. Rotate the red CRT deflection yoke (on the right of the projector–from the

rear) to achieve a level image at the center of the screen (it should be parallel to the green central horizontal line).

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9. View B.

10. Rotate the blue CRT deflection yoke to achieve a level image at the center

of the screen (it should be parallel to the green and red grid center lines).

11. Retighten the yoke clamp so it is secure. Be careful not to over-tighten it.

12. Tilt the electronics module back into place.

13. Replace the allen screw from Step 4 above.

14. Replace the rear cover.

15. After Yoke rotation, re-adjust Geometry, Convergence and CRT

Mechanical focus.

3.3 Vertical Size Tracking

If the R or B vertical size does not match G, adjust the R and B vertical size pots on the Vertical Deflection Board (see Figure 3-2).

Chapter 3---Service Adjustments

NOTE:

The tracking pots are factory adjusted and should

adjustment. The Green Vertical Size control (R-228) in particular, should

need to

be adjusted unless the Green Yoke or Green CRT has been replaced. If

not

normally need

not

the Green Vertical Linearity is off, however, it should be adjusted. In this case, Green should then be matched to Red and Blue.

The Red Vertical Size control is R-428.

➨

The Blue Vertical Size control is R-328.

➨

To adjust the vertical size controls:

1. Press Test 2 to display the White X-hatch pattern.

2. Remove the rear projector cover.

3. Remove the eight screws holding the electronics module cover

and remove the cover.

4. From the Convergence menu select #3, CLEAR CONVG AXES.

5. Position R and B over G (using the POS and arrow keys on the

remote–refer to Section 4.9) so that the R and B lines at the outer edges have the same amount of error.

6. Adjust R328 and R428 so that the Red and Blue vertical sizes

match the Green vertical size.

7. If unable to match Red or Blue to Green, adjust Green to match the

smallest color.

8. Replace the electronics module cover.

9. Replace the rear projector cover.

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Chapter 3---Service Adjustments

Blue Vertical Linearity

Blue Vertical Size

328

Red Vertical Linearity

411R311R211

Green Vertical Linearity

R 36

CAUTION!!!

Do not ad just the pots that are shaded! They are

factory adjusted. Do not adj ust the Green Vertical

Size or Green Vertical Linearit y unless the Green

Yoke or Green CRT has b een replaced.

Figure 3-3

Vertical Size and Linearity Controls on the Vertical Deflection Board.

3.4 Vertical Linearity Tracking

Green Vertical Size

228R428

Red Vertical Size

RRR

139 171

If the vertical linearity is not completely linear, use a small slot screwdriver and adjust the vertical linearity controls on the Vertical Deflection Board (refer to Figure 3-2).

NOTE:

The Vertical Linearity pots are factory adjusted and will

not

normally

need adjustment. The Green Vertical Linearity pot (R-211) in particular, should

not need

to be adjusted unless the Green Yoke or Green CRT has been replaced.

If the Green Vertical Linearity is off, however, it should be adjusted. To adjust vertical linearity:

1. Select Test Pattern 2.

2. Remove the projector cover.

3. Remove the electronics module cover.

4. View Red over Green and position Red (use the POS control and the

arrow keys on the remote) so that the Red lines at the edge match the Green lines.

5. Adjust the Red Vertical Linearity pot R-411 so that Red linearity matches

Green.

6. Repeat the same procedure for Blue (R-311).

7. Replace the electronics module cover and the projector cover.

3-6 Model 330, 340SC, 370SC Service Manual

3.5 Horizontal Size Tracking

The horizontal width coils are factory adjusted and will not normally need adjustment. In general, if the R and B vertical lines are within two (2) crosshatch lines of each other, they can be brought in line with the Convergence procedure. If the R or B horizontal size does not match G within two crosshatch lines, adjust the Horizontal Width coils on the R and B Deflection Yokes (refer to Figure 3-1). The width coils are mounted on a small circuit board on top of the Yoke assembly inside a white ceramic holder and the adjustment is accessed from the opening at the end of the ceramic holder.

Chapter 3---Service Adjustments

WARNING!!!

when performing the width coil adjustment always wear ANSI/ASTM 10,000 volt rated safety gloves for protection from the high yoke voltages that are present. Make sure the gloves are not cracked.

To adjust the horizontal size tracking:

1. Remove the rear cover and electronic module cover by removing the

2.5mm Allen screw holding the electronics module in place and tilting the electronics module (see CAUTION! below) back to gain access to the yoke.

CAUTION!

rear electronics jacks or the plugs could be badly damaged when the electronics module is tilted back.

2. View G and R.

3. Using the POS and arrow keys, position Red over Green so that each edge

of the pattern has the same amount of error. Adjust the Red coil until the edges align.

To prevent possible electrical shock

Remove anything plugged into the

4. Use a small plastic hex screwdriver to turn the red coil core (the red CRT

is on the right side looking from the rear) clockwise or counterclockwise until the Red horizontal size matches Green.

5. Cutoff R and view G and B.

5. Use a small plastic hex screwdriver to turn the blue coil core (the blue

CRT is on the left side looking from the rear) clockwise or counterclockwise until the Blue horizontal size matches Green.

6. Tilt the electronics module back into place.

7. Replace the allen screw from Step 1 above.

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Chapter 3---Service Adjustments

8. After Yoke rotation, readjust Geometry, Convergence and CRT

Mechanical focus.

3.6 ILA® Bias Settings

The ILA® Bias settings are factory set and should not normally need adjustment unless specific maintenance has been performed that requires an ILA

Bias readjustment. Avoid readjusting the ILA® Bias settings unless absolutely necessary.

The ILA

Bias settings adjust the electrical bias levels to each ILA® assembly to a "just off" threshold point so that even the smallest incoming light from the CRT makes the ILA

assembly react. When properly set, this adjustment will put each

ILA® assembly at the threshold of operation. If not properly set, image black level

will be adversely affected and the ILA

assembly won't react properly to incoming

light. ILA® Bias adjustments should be done in a darkened room.

NOTE:

If the room cannot be darkened enough to set the ILA® Biases using the screen, try holding a piece of paper a few inches from the lens of the color you are adjusting. Adjust the bias in the usual manner while viewing the entire ILA

assembly area on the paper.

Note On Super Contrast Ila® Assemblies

If using optional Super Contrast ILA® assemblies, the High Contrast Compensator may have to be adjusted for each color prior to performing the ILA® bias adjustment. This procedure is required whenever an ILA® assembly is replaced or if the compensator adjustment lever is inadvertently moved.

To set the High Contrast Compensator:

1. Press the HIDE key to mute CRT images.

2. Block the light from the green and blue lenses with the lens caps.

3. Move the front cover forward to provide access to the ILA® assemblies.

4. Disconnect the connector from the top of the red ILA® assembly.

5. Move the Compensator lever (this lever is just in front of the ILA

connector) to the right and left until the darkest level appears on the screen. If a screen is not available use a piece of white paper in front of the lens.

6. Reconnect the connector to the red ILA

7. Repeat the above steps for the green ILA® and the blue ILA®. Block the

light from the other two lenses each time.

8. Replace the cover.

9. Remove all lens caps

The CRTs will automatically cut off when you enter the ILA

light on the screen is being reflected by the ILA

To set the ILA

Frequency and Bias levels:

assembly.

Bias mode. Any

3-8 Model 330, 340SC, 370SC Service Manual

Chapter 3---Service Adjustments

1. Select ILA® Menu, from the Main Menu.

2. Select Frequency Adjust from the ILA® Bias Menu.

3. A frequency of 1.8 kHz is acceptable for general video viewing. A lower

frequency (as low as 1.5 kHz) will provide a brighter image but with lower image burn-in. A higher frequency provides higher resolution. For HDTV a frequency of 2.0-2.5 kHz provides higher resolution. Use the up/down keys to adjust the ILA® frequency for the appropriate input source. As a general rule 1.8 kHz works well with most sources.

4. Display the ILA® B

IAS MENU

again.

5. Select ADJUST, NO VIDEO. Don't attempt ILA® Bias adjustments on

Bias W/ Video. This feature is used for factory quality control only.

6. Press GREEN on the remote to select Green. Place lens caps over the Red

and Blue lenses.

7. Use the up/down arrows to adjust the Green ILA® Bias until the brightest

area of the ILA® image dissappears. Then raise the bias level until the ILA® image just starts to appear on the screen at any point. Finally, slowly lower the bias level again to the threshold point where the ILA® image just disappears.

NOTE:

It’s crucial for the optimum operation of the projector to set the bias level to the point where the selected color just begins to appear on the screen. Find the spot on the screen where the active color first begins to get brighter and use that as the reference point. Go below and above this point to find the setting where one (1) click on the UP key causes an increase in brightness and stop at that point. This will insure that the weakest video signal will cause the ILA® assembly to respond.

8. Cover the Green lens and uncover the Red lens. Press RED to select Red.

9. Repeat Step 7 for the Red ILA® Bias.

10. Cover the Red lens and uncover the Blue lens. Press BLUE to select Blue.

11. Repeat Step 7 for the Blue ILA® Bias.

12. Press Enter on the remote to save the settings and exit this adjustment.

NOTE:

The ILA® Bias settings affect other projector settings. When ILA Bias has been adjusted, verify and readjust, if necessary, all projector adjustments from the appropriate section of the specific model Operator’s Manual.

3.7 CRT Mechanical Focus

The CRT mechanical focus is factory set and will normally not need to be adjusted. Whenever a major component (like a CRT or a HVPS) has been replaced or repaired the CRT mechanical focus must be reset. Use Test Pattern 8, H-Grid and observe the corners of the screen. If the corners are all in sharp focus,

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Chapter 3---Service Adjustments

the mechanical CRT focus should not be adjusted. If the image is not sharp enough, proceed with the CRT mechanical focus adjustment below.

There are three (3) adjustment rods for each CRT making a total of nine (9). The rods are accessed through holes, covered by hole caps, in the base and fan casing at the rear of the projector (see Figure3-3).

The focus rods will be adjusted so that each CRT face is completely parallel to its respective ILA® assembly, (i.e. positioning the CRT screen face planar with the ILA® along the x, y and z axes).

Each CRT has three (3) focus rods; lower-left, lower-right and upper-left. The focus rods for each CRT work as follows (see Figures 3-3 and 3-4).

The lower-left rod adjusts the CRT to ILA® distance (zaxis) for upper-right corner and overall focus.

The lower-right rod adjusts the bottom position of the CRT

The upper-left rod adjusts left-side position of the CRT.

Figure 3-4

CRT Focus Adjustment Apertures. Use a 5mm nutdriver to adjust the focus

rods inside the apertures.

3-10 Model 330, 340SC, 370SC Service Manual

JVC 340 SC, 370 SC, 330 User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual