Hughes JVC Projector 250 Sc Service Manual

							Chapter 5---Electronics
5-76 Model 250 Service Manual
Figure 5-44  
Backplane Diagram (right side). 
						

							Chapter 5---Electronics
Model 250 Service Manual 5-77 
						

							Chapter 6---Miscellaneous Items
Model 250 Service Manual 6-1
6.0 Miscellaneous Items
Contents
6.1  Projector Covers ........................................................................................... 6-1
6.2  Electronics Module Tilt-up .......................................................................... 6-2
6.3  Ventilation .................................................................................................... 6-3
6.4  Air Filters ..................................................................................................... 6-4
6.5  IR Detectors.................................................................................................. 6-4
6.6  EMI Shield ................................................................................................... 6-4
6.7  Cleaning Lenses, ILA
® Assemblies, and Mirrors ........................................ 6-5
6.1 Projector Covers
There are two projector covers, one that covers the front of the projector and one
that covers the rear. The are attached and hinged to the Cross-Member Assembly.
The covers can be tilted up (see CAUTION below) or removed from the projector
to perform service procedures. The projector covers provide a stylish, professional
appearance to the projector, however they also protect operators from exposure to
high voltages and very bright light. Review the Safety chapter and adhere to all
warnings and cautions.
  CAUTION!  Do not leave either cover in the tilted up
position! The covers can fall from this tilted up position and possibly
damage projector components. Remove the cover and set it aside when
servicing the projector.
Tools Needed
#1 Pozi-drive Phillips-head screwdriver
To remove the front or rear covers:
1. Disconnect the projector power plug.
2. Loosen the two Pozi-drive Phillips-head spring screws at the front of the
front cover or the rear of the rear cover.
3. Tilt up the front or rear cover.
4. Release the two Latch Levers on the Cross-member assembly that hold the
cover in place. Place the ends of the Latch Levers into the holding slots. 
						

							Chapter 6---Miscellaneous Items
6-2 Model 250 Service Manual
5. When the Latch Levers are inserted into the holding slots, lift the cover
off. Be careful not to brush against any of the internal components of the
projector when removing the cover. If any undue resistance is felt, stop to
locate the source before proceeding.
6. Replace the covers in reverse order. When replacing either cover, make
sure the slot in the cover fits over the bottom of the projector case or the
cover will not close correctly.
6.2 Electronics Module Tilt-up
The Electronics Module contains all the electronic Printed Circuit Boards for the
Module 250 Projector except for the Video Amplifier PCB and its three
associated CRT socket PCBs. It is located in the rear of the projector. The
Electronics Module can be tilted to a 45° or 90° angle to access and perform
service procedures on ILA
®s, CRTs or the Video Amplifier PCB.
To tilt the Electronics Module up:
1. Remove the rear cover.
2. Unlatch the Electronics Module (see Figure 6-1)
3. The locking pin secures the Electronics Module in place at 0°, 45° or 90°
rotation with the locking pin. The Electronics Module locking pin is
located on the rear Electronics Module hinge on the right side of the
Electronics Module.
4. Pull the locking pin out.
5. Lift the left side of the Electronics Module up while continuing to hold the
locking pin out.
6. Release the locking pin when the Electronics Module is in the desired
position and ensure that it snaps into place.
7. Reverse process to tilt Electronics Module down. 
						

							Chapter 6---Miscellaneous Items
Model 250 Service Manual 6-3
Figure 6-1  
Electronics Module hinge and locking mechanism.
6.3 Ventilation
Adequate cooling is a major consideration for the Model 250 projector. There are
thirteen cooling fans (including the Arc Lamp blower) in this projector.
!
 4 fans in the main chassis - two in the rear of the projector, one in the right
front corner and one on the bottom of the projector. These fans bring cool
air into the chassis of the projector. Each of these fans has an air filter in
front of it.
!
 3 fans in the Electronics Module -  two smaller fans force cool air across
the Horizontal Vertical Deflection PCB on the top of the Electronics
Module and one large fan forces cool air into the body of the Electronic
Module
!
 3 fans in the Optics Module - one fan draws hot air from the #1 Cold
Mirror, the other two fans draw hot air off of the Prism Assembly.
!
 3 fans for the Arc Lamp Module - one large fan is mounted on the door of
the Arc Lamp housing, with one smaller fan mounted on the top. The large
blower is on the side of the Arc Lamp housing. All of these fans force cool
air in to cool the Arc Lamp.
All cooling fans are powered by +24 V from the Low Voltage Power Supply
except the large blower for the Arc Lamp. The large blower is powered by AC
power that is switched on and off by a relay switch. The relay switch is powered
by +24 V so effectively, the +24 V turns on all the cooling fans.  The cooling fans
turn on as soon as the AC Circuit Breaker is powered ON. 
						

							Chapter 6---Miscellaneous Items
6-4 Model 250 Service Manual
6.4 Air Filters
There are three polyurethane air filters in the Model 250. Air filters should be
cleaned whenever necessary. In extremely dusty or dirty conditions, the filters
should be cleaned more frequently. Remove the filters and vacuum them or blow
them clean with compressed air.
The air filters just slide out. No tools are required to remove and reinstall any of
the air filters. They are located as follows:
!
 1 metal-framed filter in the rear of the projector in the bottom cover-
accessible when the rear cover is off.
!
 1 filter on the bottom of the projector-slides out from the middle-left side
of the projector (grasp the hole in the filter frame). The filter can be peeled
off the Velcro on the frame, if necessary.
!
 1 metal-framed filter in the front-left-bottom cover accessible with the
front cover off.
6.5 IR Detectors
The IR Detectors receive command signals from the IR Remote Control. The
Model 250 projector has two IR Detectors, one on the front of the projector and
one on the rear (mounted on the System Controller PCB). The command signals
go to the System Controller PCB where they are distributed to the various PCBs,
typically by way of the IIC data bus. The IR Detectors can receive commands
from an IR Remote Control from a range of about 45-ft. line of sight.
6.6 EMI Filter
Figure 6-2  
EMI Shield with Low Voltage Power Supply and Arc Lamp Power
Supply behind it
The purpose of the Electro-Magnetic Interference (EMI) Shield is to trap and
collect electromagnetic radiated fields generated by switching power supplies.
Switching power supplies radiate high frequency noise that may interfere with
radios, televisions, and other electronic appliances. The EMI Shield is constructed
of a special Mu metal that acts as an antenna to collect and ground the high
frequency noise as required by the Federal Communications Commission and
various other regulatory agencies. 
						

							Chapter 6---Miscellaneous Items
Model 250 Service Manual 6-5
The EMI Shield is a metal plate located in front of the Low Voltage Power
Supply and the Arc Lamp Power Supply. It must be removed before removing
either of these power supplies. Be sure to replace the EMI Shield after replacing
either the Low Voltage Power Supply or the Low Voltage Power Supply.
6.7  Cleaning Lenses, ILA® Assemblies and Mirrors
The projection lens is the only item that requires periodic cleaning. Other
assemblies are covered to prevent dust entering or finger smudging. Cleaning may
be needed for special circumstances such as replacing an assembly. Cleaning
should only require removing excessive dust (use canned air such as “Office
Duster” or Aero Duster) or removing fingerprint smudges (use “Kodak Lens
paper”, or equivalent) from the projection lens. As much as possible, clean the
optics only when absolutely necessary.
Projection Lens - Use lens paper and wipe the lens clean in a vertical motion from
top to bottom. Use compressed air to blow excess dust from the lens. An optical
lens cleaning solution can also be used to remove finger smudges.
ILA
® Assembly - Clean the ILA® assembly faces with compressed air only. Do
not wipe the ILA assembly faces.
CRT Faces - Use compressed air to blow dust off and lens paper to clean face.
Relay Lens - Same as Projection Lens.
Mirrors and Polarizing Beam Splitter Windows - The Optical Shields cover the
Dichroic Mirror Assembly and Polarizing Beam Splitter windows. Normally
cleaning is not needed. Clean only if absolutely necessary using compressed air.
Do not wipe mirrors. 
						

							Chapter 6---Miscellaneous Items
6-6 Model 250 Service Manual 
						

							Chapter 7---Troubleshooting
Model 250 Service Manual 7-1
7.0 Troubleshooting
Contents
7.1  Safety............................................................................................................ 7-1
7.2  LEDs............................................................................................................. 7-2
Backpanel LEDs......................................................................................... 7-2
Video Processor PCB LEDs....................................................................... 7-5
Raster Timing Generator PCB LEDs ......................................................... 7-7
Convergence Deflection PCB LEDs .......................................................... 7-9
Video Amplifier PCB LEDs ...................................................................... 7-10
Backplane PCB LEDs ................................................................................ 7-11
7.3  Diagrams ...................................................................................................... 7-12
Image Path .................................................................................................. 7-14
Deflection Path ........................................................................................... 7-15
CRT Protection........................................................................................... 7-19
7.4  Error Codes .................................................................................................. 7-22
7.5  Troubleshooting Guide................................................................................. 7-25
Troubleshooting on the Backplane PCB .................................................... 7-26
7.1 Safety
  CAUTION!  
Before performing procedures in this chapter,
review the chapter on Safety at the beginning of this manual.
  WARNING!!!  When performing troubleshooting
procedures that require projector covers to be off, wear high voltage
gloves (ANSI/ASTM 10,000 volt rated) when working near 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
. 
						

							Chapter 7---Troubleshooting
7-2 
Model 250 Service Manual
Left/Right Orientation: When referring to the left or right in this chapter, it is
with reference to standing at the rear of the projector, facing the screen
.
Connectors
 on subassemblies and PCBs have tabs that must be released first
before pulling on the connector. The proper procedure is to push slightly 
IN on
the connector, then squeeze the tab, then pull the connector out.
7.2 LEDs
Backpanel LEDs
This section covers the various terminals, detectors, and LEDs visible from the
rear and left side of the projector with the rear projector cover and rear panel
removed.
Operation Status LED - This LED indicates the status of the projector. When the
LED is illuminated green, the projector is operating normally. When the LED is
illuminated orange, the projector is in standby mode, which means that the
projector has AC power but has not yet received a POWER ON command. If the
LED is illuminated flashing red, the projector has experienced an error and will
display an error code (see Table 7-1 and Table 7-2).
Service Mode Switch - The Service Mode Switch is used when updating software
to the CPU. The projector must POWERED OFF and the AC Circuit Breaker
must be cycled off. The Service Mode Switch is pushed while turning the AC
Circuit Breaker ON. This starts the projector in the Service Mode. The Software
Update section (see Software Updating, section 8.1) contains the full procedure
for updating CPU software.
Terminal In - The Terminal In is a RS232 port used to communicate with the
projector or Import/Export setup data using a PC or Laptop computer, a switching
device such as a Crestron Control Switcher, or the optional Tethered Technician
Remote Control.