JVC 330 User manual

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 FAX [phone] e-✉serv[email protected]
DECLARATION OF CONFORMITY
PER ISO/IEC GUIDE 22 AND EN 45014

iii Model 330, 340SC and 370SC Service Manual
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
Confidential and proprietary information.
© Copyright 1998 by Hughes-JVC Technology Corporation.
All worldwide rights reserved.
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.
ILA®is a registered trademark of Hughes-JVC Technology Corporation.
Hughes-JVC Technology Corporation
is ISO 9001 Registered and Certified.

Safety
Model 330, 340SC, and 370SC Service Manual v
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.
Warnings and Cautions
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!!! Warns user of a potential electric shock hazard
and/or specific procedure or situation that could result in personal injury if
improperly performed.
CAUTION! Warns user of a potential safety hazard or potential light
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.
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

Safety
vi Model 330, 340SC, and 370SC Service Manual
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!!! If there is any visible damage to any of the cables do
not power on the projector until the damaged cable is replaced.
CAUTION!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.

Safety
vii Model 330, 340SC, and 370SC Service Manual
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!Do Not Block Ventilation. Blocking air intake or exhaust
ports can lead to projector overheating. Do not enclose the unit in a restricted
space. Refer to the appropriate Operator’s Manual for physical access and
thermal clearance and for specific clearances needed for heat dissipation. Allow
at least ten (10) minutes for projector cool down before removing power.
CAUTION!Do not unplug the power cord until after the arc lamp fan
has stopped running. This fan protects the arc lamp from overheating.
Light Safeguards
Ultra Violet and Infrared Light
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.

Safety
viii Model 330, 340SC, and 370SC Service Manual
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.
WARNING!!!High voltage access and safety interlock. Defeat
restricted to factory authorized service personnel!
WARNING!!!High voltage points up to 40,000 volts are exposed inside the covers.
Allow at least one minute to bleed off high voltage even after the unit has been turned off.
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.

Safety
ix Model 330, 340SC, and 370SC Service Manual
!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 330 340SC 370SC
AC 200-240V 200-240V 200-240V
Current 20 20 30
Hz 50-60 50-60 50-60
Watts 2,700 3,325 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.

Safety
xModel 330, 340SC, and 370SC Service Manual
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 prior to attempting any of these procedures.

Safety
xi Model 330, 340SC, and 370SC Service Manual

Chapter 1---Introduction
Model 330, 340SC and 370SC Service Manual 1-1
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.
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

Chapter 1---Introduction
1-2 Model 330, 340SC and 370SC Service Manual
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 Hardware Compatibility
Printed Circuit Boards 330 340SC 370SC
DIFFERENT PART NUMBERS
Lamp Assembly 900611S 104651 104120
Ignitor 102083 102207 104475
System Power Supply 104070 104071 104038
High Voltage Power Supply 100562 100562 103769
SAME
Raster Timing Generator 100568 100568 100568
Horizontal Deflection Board 102523 102523 102523
Vertical Deflection Board 102521 102521 102521
Video Processing Board 104672 104672 104672

Chapter 1---Introduction
Model 330, 340SC and 370SC Service Manual 1-3
Printed Circuit Boards 330 340SC 370SC
Video Amplifier Board 103774 103774 103774
System Controller Board 104668 104668 104668
Table 1-2 Projector Model Comparisons
330 Model 340SC Model 370SC Model
Different
3,000 lumens 4,200 lumens 6,800 lumens
2,500 ANSI lumens 3,700 ANSI lumens 6,000 ANSI lumens
220V AC, 20A, 60Hz 220V AC, 20A, 60Hz 220V AC, 30A, 60Hz
2,700 Watts power 3,325 Watts power 4,550 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 5.2.1 software 5.2.1 software
graphics enhancement graphics enhancement graphics enhancement
30 memories 30 memories 30 memories
decoder board option decoder board option decoder board option

Chapter 2—Functional Descriptions
Model 330, 340SC and 370SC Service Manual 2–1
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.

Chapter 2—Functional Descriptions
2–2 Model 330, 340SC, and 370SC Service Manual
System
Power
Supply
Line Voltage
System
Controller
Lamp Ignitor
Video
Processor
Low Voltage
Power Supply Arc Lamp
Vertical
Deflection
and
Convergence
Horizontal
Deflection
Video Output
Amplifier
Raster
Timing
Generator
Image Light
Amplifiers
(3 each
Fans
High Voltage
Power Supply
RS 232
Infrared Remote
Channel 1
Channel 2
(R,G,B, H/V Sync)
CRTs
(3 each)
Figure 2-1 Model 330, 340SC and 370SC System Block Diagrams
2.1 Cover and Base
CAUTION! The covers for the HJT Model 330, 340SC
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.
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.

Chapter 2—Functional Descriptions
Model 330, 340SC and 370SC Service Manual 2–3
WARNING!!! The HJT Model 330, 340SC and 370SC
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
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

Chapter 2—Functional Descriptions
2–4 Model 330, 340SC, and 370SC Service Manual
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.

Chapter 2—Functional Descriptions
Model 330, 340SC and 370SC Service Manual 2–5
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.

Chapter 2—Functional Descriptions
2–6 Model 330, 340SC, and 370SC Service Manual
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 +24V STB +6.3V +15V -15V +24V +48V+107V -200V
Figure 2-2 Backplane Status Indicators.
A safety interlock switch is located on top of the power supply. The interlock
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.

Chapter 2—Functional Descriptions
Model 330, 340SC and 370SC Service Manual 2–7
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
STANDBY/
I/O CONTROL
+5v, +24v J502
J500
J503 (-)
J504 (+)
To
Backplane
To
Arc Lamp
Via
Ignitor
POWER
FACTOR
CORRECTION
LOW VOLTAGE
Power Supply
+5v,+6.3v,+-15v,
+24v,+48v,+107v
ARC LAMP
Power Supply
and Boost
+22v/68a ∇
+170v/1.0a
/LVPSNBL
/ALENBL
From
System
Controller
/FANENBL
J502
∇Model 330. Model 340SC = +25V/80a; Model 370SC = +30V/100a.
Figure 2-3 System Power Supply Block Diagram.
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.

Chapter 2—Functional Descriptions
2–8 Model 330, 340SC, and 370SC Service Manual
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 System Power Supply Voltage Distribution
Voltage F a
n
HV
PS CRT SCB HDB VDB VPB RTG VAB Arc
Lamp/
Ignitor
+5v
+5v Stb
+6.3v
+15v
-15v
+24v
+24v Stb
+48v
+107v
+170v