Hughes Jvc 220 Projector Service Manual

							  Chapter 1---Introduction 
1.0  Introduction 
This Service Manual is designed to be used with the Model 220 
User’s Guide. This service manual provides information on the: 
—  Projector functional description; 
—  Service adjustments, removal and replacement of 
subassemblies; and 
—  Troubleshooting. 
The user’s guide covers the projector’s installation, operation, 
setup adjustments, and specifications.  Together the service 
manual and user’s guide provide a qualified service person with 
information to operate and maintain the projector. 
1.1 Safety 
This projector contains high voltages and high intensity light 
sources in its internal system and power supplies.  Read entire 
Safety Chapter at the front of this manual before performing any 
adjustments or maintenance.  
When performing procedures that call for projector’s power to be 
on, always wear high voltage gloves (ANSI/ASTM 10,000 volt 
rated) when working around the CRTs, Arc Lamp or power 
supplies. Wear safety goggles (rated X5) when working anywhere 
near the light path from the Arc Lamp or the projection lens at all 
times. 
1.2  Updates 
Hughes-JVC will periodically provide bulletin and /or manual 
supplements to ensure the accuracy of this service manual. 
1.3 Tool List 
The following tools are required to perform service adjustments: 
All Purpose Tools=Diagonal Sidecutters, Wirestrippers, 
Slot Adjustment Screwdriver (Tweeker), 
Mirror/Magnet Pick-Up Tool, Flashlight, 6” Crescent 
Wrench, Needlenose pliers, 6” Vise Grips 
Balldriver, 1.5mm 
Balldriver, 3mm 
Balldriver, 3mm, Long 
Balldriver, 4mm 
Balldriver, 5mm, Long, T-handle 
Balldriver, 6mm 
Model 220 Service Manual  1-1  
						

							Chapter 1---Introduction 
Balldriver, 8mm 
Ballpoint L-Wrench Set, 1.5-5mm 
Delrin .100 Hex Alignment Tool 
Gloves, ANSI/ASTM 10,000 volt rated, Safety 
Goggles, Safety, x3(covers on) and x5(covers off) 
Hex Ballpoint Driver, 3mm 
Hex Ballpoint Driver, 5mm 
Nutdriver, 10mm 
Nutdriver, 11mm (or 7/16”) 
Nutdriver, 5mm 
Nutdriver, 7mm 
Nutdriver, 8mm 
Screwdriver, Phillips, #1 
Screwdriver, Phillips, #2 
Screwdriver, Pozidrive, #1 
Screwdriver, Pozidrive, #2 
Screwdriver, Slot ¼” 
Screwdriver, Slot, ½” 
Screwdriver, Slot, 3/16” 
Socket, ¼” drive, 7mm-deep 
 
1.4 Acronyms Used in this Manual 
ALPS Arc Lamp Power Supply 
CDB  Convergence/Deflection Board 
CH  Channel 
CPU  Central Processing Unit 
CRT  Cathode Ray Tube 
EMI  Electromagnetic Interference 
FLASH  Erasable Programmable Read-Only Memory 
EPROM 
FPGA Field Programmable Gate Array 
F to V Frequency to Voltage 
G2  CRT Grid 2 
HVDB Horizontal/Vertical Deflection Board 
HDTV High Definition Television 
Hz  Hertz 
HSYNC Horizontal Sync 
HVDB Horizontal/Vertical Deflection Board 
HVPS High Voltage Power Supply 
IIC  Inter-Integrated Circuit 
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 
PAL  Phase Alternating Line 
PCB  Printed Circuit Board 
PLL  Phase Lock Loop 
1-2  Model 220 Service Manual  
						

							  Chapter 1---Introduction 
PLUGE Picture Line-Up Generating Equipment 
RAM  Random Access Memory 
RGB  Red, Green and Blue 
RGBHV Red, Green, Blue, Horizontal, Vertical 
ROM  Read Only Memory 
RTG  Raster Timing Generator 
SCB  System Controller Board 
SECAM Sequential couleur a memoire (sequencial  
  color with memory 
SRB  Scan Reversal Board 
SYNC Synchronization 
TTL  Transistor-Transistor Logic 
UL  Underwriter Laboratories 
UV  Ultraviolet 
VAB  Video Amplifier Board 
VCO  Voltage Controlled Oscillator 
VIC  Video Input Card 
VIN  Video Input 
VPB  Video Processor Board 
VSYNC Vertical Sync 
VTR  Video Tape Recorder 
YC  Luminance/Chrominance 
Model 220 Service Manual  1-3  
						

							Chapter 1---Introduction 
1-4  Model 220 Service Manual 
  
						

							Chapter 2---System Description 
2.0   System Description 
  Contents 
2.1   Introduction........................................................................\
......2-1 
2.2   Optical System........................................................................\
.2-2 
2.2.1   Image Path...................................................................2-2 
2.2.2   Arc Lamp Light Path....................................................2-4 
2.3   Electronics System..................................................................2-7 
2.3.1   General Description.....................................................2-7 
2.3.2   Power Supplies............................................................2-8 
2.3.3   Video Input Cards........................................................2-13 
2.3.4   Video Processor PCB..................................................2-23 
2.3.5   Video Amplifier PCB....................................................2-28 
2.3.6   System Controller PCB................................................2-32 
2.3.7   Raster Timing Generator PCB.....................................2-38 
2.3.8   Horizontal/Vertical Deflection PCB..............................2-43 
2.3.9   Convergence/Deflection PCB......................................2-49 
2.3.10 Scan Reversal PCB.....................................................2-55 
2.3.11 Backplane PCB............................................................2-60 
2.4   Image Light Amplifier Technology...........................................2-61 
 
2.1   Introduction 
The assemblies and components in the Model 220 projector are 
contained mainly in the five sections below: 
• The Optics Assembly Section is located at the front area of 
the projector. The Optics Assembly Section includes the Cold 
Mirror/IR Filter, (CAUTION!: The term cold mirror is used 
because the mirror passes infrared light and its reflection 
contains only cold light that does not transmit appreciable 
heat. As a result of the absorption of infrared heat radiation, 
cold mirrors can get very hot.), Second Condensing Lens 
Ultraviolet Filter, Diffuser, Dichroic Mirror Assembly, Prisms, 
Combining Prism, Image Mirrors, and the Zoom Projection 
Lens. 
• The Arc Lamp Assembly section is located in the right front 
area of the unit. It contains the Ignitor, Laser Power Supply, 
Xenon Arc Lamp and First Condensing Lens. 
  
Model 220 Service Manual  2-1  
						

							Chapter 2---System Description 
• The Power Supply Section is located at the right front area of 
the projector below and to the rear of the Arc Lamp. It contains 
the Low Voltage Power Supply, the High Voltage Power 
Supply, and the Arc Lamp Power Supply. 
• The Projector Electronics Section is located mainly in the 
back half of the projector. It consists of the Electronics Module 
that houses 6 of the electronics printed circuit boards used in 
the projector, and their associated cabling. It also contains the 
Backplane board which is used to electrically interconnect the 
printed circuit boards, power supplies and various other units 
in the projector, and the Video Input Cards that interface with 
different kinds of input signals. 
• The CRT Section is located beneath the electronics card cage 
and contains the 3 CRTs, 3 Relay Lenses, 3 ILA®s and the 
Video Amplifier Board. 
2.2   Optical System 
Introduction: The Model 220 Optics Assembly divides white light 
from the Arc Lamp into its three color components, Red, Green 
and Blue. This light is then modulated with the image signal to 
form three single color images. The light is then recombined at the 
4P (combining) prism and transmitted through the projection lens 
to the projector screen. The explanation below is divided into two 
sections. The first section follows the image path from the CRT to 
the projector screen. The second section follows the high intensity 
light path from the Arc Lamp Ignitor to the ILA® assemblies, where 
it combines with the image. The Red, Green, and Blue image and 
light paths are identical. Refer to Figure 2-1. 
CAUTION! The alignment of system optical 
components is critical. Replacement of individual mirrors or prisms 
requires removing the projector cover and must be performed only 
by Hughes-JVC Certified technicians. Consult the factory before 
removing or aligning any mirrors or prisms. 
2.2.1   Image Path 
CRT Assemblies: The three CRT/Yoke assemblies are located 
beneath the Electronics Module card cage. Two exhaust fans at 
the rear help cool the CRT assemblies. Each CRT is sent a red, 
green, or blue signal, but they do not emit a red, green, or blue 
color, as in traditional projectors. The CRTs are not used as a 
primary light source. The light output to the screen is the function 
of the Arc Lamp. The purpose of the CRTs is to generate an 
2-2 Model 220 Service Manual  
						

							Chapter 2---System Description 
image and to control the amount of modulation the ILA® 
assemblies introduce on the light coming from the Arc Lamp. The 
Red, Green, and Blue image signals are routed to the CRTs from 
the Video Amplifier Board through the CRT socket connectors. 
Relay Lens: The relay lens picks up the image from the face of 
the CRT and focuses the image to the ILA® assembly. 
Image Light Amplifier (ILA®) Assembly: The CRT image is 
received from the relay lens onto the input side of the ILA® 
assembly. The input and output sides of the ILA® assembly are 
isolated from each other electrically and optically but are coupled 
electrostatically. 
At the same time as the image is received at the input side of the 
ILA® assembly, the output side of the ILA® assembly is receiving 
high intensity light from the arc lamp through the prism. This high 
intensity light is modulated (changing its polarization) by the signal\
 
on the input side of the ILA® assembly. The light is then reflected 
back from the output side of the ILA® assembly, then travels 
through the prism to be picked up by the projection lens.  
NOTE: The prism reflects horizontally polarized light and passes 
vertically polarized light. Light from the arc lamp is polarized 
horizontally and reflects from the prism into the ILA® assembly 
then back out again, after being modulated by the image signal 
into vertically polarized light. The vertically polarized light then 
passes through the prism to the projector lens. In this manner the 
ILA® assembly combines the image from the CRT with the high 
intensity light from the arc lamp. Thus, the maximum brightness of 
the screen image is not dependent on the brightness of the CRT, 
but on the light from the arc lamp. 
For a more detailed description of how the ILA® assembly works, 
refer to Section 2.7 below. 
Polarizing Prism: The polarizing prism receives the high intensity 
light from the xenon arc lamp and polarizes the light horizontally. 
The prism reflects virtually all of this light toward the ILA® 
assembly. This light is then modulated (altered) into a vertical 
plane by the image on the input side of the ILA® assembly and 
then reflected back into the same prism. Since the prism reflects 
only horizontal light and passes vertical light, this high intensity, 
vertically polarized image goes straight through the prism toward 
the Combining Prism. Light that is not completely polarized 
horizontally or vertically passes through the prism in varying 
degrees of brightness, according to how polarized it is (fully 
polarized light resulting in maximum brightness on the screen). 
Image Mirror: The Image Mirrors direct the blue and red images 
toward the Combining Prism. 
Model 220 Service Manual  2-3  
						

							Chapter 2---System Description 
Combining (4P) Prism: The combining prism consists of 
separate prisms that polarize each of the three high intensity 
signals and direct them toward the projection lens. 
Projection Lens: The Projection Lens picks up the high intensity 
image from the Combining Prism and transmits it to the projector 
screen. 
2.2.2   Arc Lamp Light Path 
The Arc Lamp assembly produces the high intensity light used to 
transmit bright images to the screen. It consists of a Xenon Arc 
Lamp containing xenon gas under pressure, a Condensing Lens 
bolted to the arc lamp housing, an Ignitor assembly that provides 
the spark to light the arc lamp, a Laser Power Supply to provide 
the boost voltage to the Ignitor. An exhaust fan helps keep the arc 
lamp cool. The description below follows the sequence of the light 
path. (See Figure 2-1). 
Ignitor and Laser Power Supply: The Laser Power Supply 
provides a boost voltage through a spark gap to the Ignitor circuit 
which then provides a momentary High Voltage, (about 32 KV), to 
excite the xenon gases inside the Xenon Arc Lamp. After the arc 
lamp ignites, it is maintained ON by high current and low-voltage 
(approximately 47.5 amps and +20 volts). The Ignitor and Laser 
Power Supply are mounted on the base next to the arc lamp.  
WARNING!!!  The Xenon Arc Lamp produces high 
intensity white, ultraviolet and infrared light capable of severe eye 
injury. Never look directly at or touch the Xenon Arc Lamp. 
Service should be performed by Hughes-JVC certified 
technicians only. 
Xenon Arc Lamp/Condensing Lens: High pressure, ionized 
xenon gas supports a high-current electrical arc to produce the 
intense, white light used in the Model 220 projector.  
First Condensing Lens (Asphere): The high intensity light output 
from the Xenon Arc Lamp is picked up by the First Condensing 
Lens (attached to the rear of the Arc Lamp housing) where the 
light beam is condensed and directed toward the Cold Mirror/IR 
Filter. 
Cold Mirror/IR Filter: The Cold Mirror/IR Filter removes most of 
the IR light and directs the light beam toward the Second 
Condensing Lens. 
Second Condensing Lens/UV Filter: Final condensing for the 
light beam is provided by the Second Condensing Lens. 
Ultraviolet light is filtered out by the UV Filter. 
Diffuser: The Diffuser diffuses the light beam out more evenly 
and reduces flicker. 
2-4 Model 220 Service Manual  
						

							Chapter 2---System Description 
The high intensity light beam then proceeds toward the Dichroic 
Mirror Assembly. Thus, most of the IR and UV light is filtered out 
before the light beam enters the more sensitive portions of the 
optics, leaving only the visible portion. 
Dichroic Mirror Assembly: The condensed and filtered white 
light beam enters the Dichroic Mirror Assembly which separates 
(dichroic mirrors reflect only one color and pass all others) the 
light into its Red, Green and Blue components. The first mirror in 
the Dichroic Mirror Assembly reflects blue light to the blue ILA® 
assembly, the second mirror reflects green light to the green ILA® 
assembly, and the third reflects red light to the red ILA® assembly. 
Thus, each ILA® is sent only one color of light. 
Prepolarizers and Polarizing Prisms: Each individual light beam 
is polarized (directed) toward its own Polarizing Prism where it is 
directed toward the output side of its ILA® Assembly and 
combined with the signal from the input side of the ILA® 
Assembly. 
Each of these three light beams independently combine with the 
image in their own (Red, Green or Blue) color systems at the ILA® 
assemblies as described in Section 2.2.1, Image Path. 
 
Model 220 Service Manual  2-5  
						

							Chapter 2---System
 Description 
Figure 2-1.  Optical Sy
stem Block Diagram
 
2-6
 
 
Model 220 Service Manual