Hughes Jvc 220 Projector Service Manual

							Chapter 2---System Description 
 
X_GRN+ Output of horizontal green convergence amplifier 
X_BLU+ Output of horizontal blue convergence amplifier 
Y_RED+ Output of vertical red convergence amplifier 
Y_GRN+ Output of vertical green convergence amplifier 
Y_BLU+ Output of vertical blue convergence amplifier 
OUTPUTS DESCRIPTION 
X_RED- Current feedback of horizontal red convergence amplifier 
X_GRN- Current feedback of horizontal green convergence amplifier 
X_BLU- Current feedback of horizontal blue convergence amplifier 
Y_RED- Current feedback of vertical red convergence amplifier 
Y_GRN- Current feedback of vertical green convergence amplifier 
Y_BLU- Current feedback of vertical blue convergence amplifier 
RED YOKE CONNECTOR 
NAME DESCRIPTION 
H_RED_YOK+ Top of red horizontal yoke 
H_RED_YOK- Bottom of red horizontal yoke 
RED_LOCK+ Interlock for red yoke. 5 V when closed or 15 V when open. 
RED_LOCK- Interlock for red yoke. 5 V when closed or 0 V when open.  
V_RED_YOK+ Top of red vertical yoke 
V_RED_YOK- Bottom of red vertical yoke 
X_RED_YOK+ Top of red horizontal convergence yoke 
X_RED_YOK- Bottom of red horizontal convergence yoke 
Y_RED_YOK+ Top of red vertical convergence yoke 
Y_RED_YOK- Bottom of red vertical convergence yoke 
GREEN YOKE CONNECTOR 
NAME DESCRIPTION 
H_GRN_YOK+ Top of green horizontal yoke 
H_GRN_YOK- Bottom of green horizontal yoke 
Model 220 Service Manual  2-57  
						

							  Chapter 2---System Description 
 
GRN_LOCK+ Interlock for green yoke. 5 V when closed or 15 V when open. 
GRN_LOCK- Interlock for green yoke . 5 V when closed or 0 V when open.  
V_GRN_YOK+ Top of green vertical yoke 
V_GRN_YOK- Bottom of green vertical yoke 
X_GRN_YOK+ Top of  green horizontal convergence yoke 
X_GRN_YOK- Bottom of green horizontal convergence yoke 
Y_GRN_YOK+ Top of green vertical convergence yoke 
Y_GRN_YOK- Bottom of green vertical convergence yoke- 
BLUE YOKE CONNECTOR
NAME DESCRIPTION 
H_BLU_YOK+ Top of blue horizontal yoke 
H_BLU_YOK- Bottom of blue horizontal yoke 
BLU_LOCK+ Interlock for blue yoke. 5 V when closed or 15 V when open. 
BLU_LOCK- Interlock for blue yoke . 5 V when closed or 0 V when open.  
V_BLU_YOK+ Top of blue vertical yoke 
V_BLU_YOK- Bottom of blue vertical yoke 
X_BLU_YOK+ Top of  blue horizontal convergence yoke 
X_BLU_YOK- Bottom of blue horizontal convergence yoke 
Y_BLU_YOK+ Top of blue vertical convergence yoke 
Y_BLU_YOK- Bottom of blue vertical convergence yoke- 
 
2-58 Model 220 Service Manual  
						

							Chapter 2---System Description 
2.3.11 Backplane PCB 
The Backplane PCB is the interface that connects the Power 
Supplies, VICs, PCBs, and other components together, either 
through a direct connection to a connector on the Backplane or 
through cables to connectors on the Backplane PCB. Signals are 
not modified in any way by the Backplane. It serves only as an 
interconnecting point. Refer to Figure 2-17 for a general idea of 
how the projector wiring is interconnected through the Backplane 
PCB. 
Backplane
PCB
P8
P12
P14
P18
P9
P7
P72ALPS
HVPSP43
P4P32
CDBP3P31
P10
P11
SCB
P13RTG
P16
P17
VPB
P1P67
VAB
P2P68
P6P36
HVDB
P5P35
P19Proj LensP62
Fans
P76LVPS
VIC #1
VIC #2
VIC 3#
 
Figure 2-17.  Backplane Board Interface Block Diagram. 
Model 220 Service Manual  2-59  
						

							  Chapter 2---System Description 
2.4   Image Light Amplifier Technology 
Section 2.2 explained how the various units, including the ILA® 
assemblies, in the Optical System work together to produce the 
image on the screen. This section focuses mainly on how the ILA® 
assembly itself works. 
An Image Light Amplifier (ILA®) assembly (Figure 2-18) is a 
device that uses low-intensity images to modulate a high-intensity 
light through a liquid crystal layer. It is the key component in 
producing very bright, high resolution images from Hughes-JVC 
large-screen projectors.  
 
Figure 2-18.  The Hughes-JVC Image Light Amplifier®. 
Optically, there are two sides to an ILA® assembly with a light 
blocking layer in the center. On the input side there is a photo-
conductive layer where the image from a CRT is focused through 
a relay lens. This image is electrostatically coupled through the 
light-blocking layer and mirror to a liquid crystal layer on the output \
side of the ILA® assembly.  
2-60 Model 220 Service Manual  
						

							Chapter 2---System Description 
High intensity light from a Xenon Arc Lamp is applied, through a 
prism (where it is polarized), to the output side of the ILA® 
assembly where the liquid crystal layer is located. The polarized 
light passing through the liquid crystal is modulated (changing the  
polarity of the light waves), in accordance with whatever image is 
on the input side of the ILA® assembly.  
The axis of the polarized light is proportional to the brightness on 
the input side of the ILA® assembly. When the photoconductor on 
the input side is not illuminated, the liquid crystal does not rotate 
the polarized light from the Arc Lamp. No light passes through the 
prism and the screen is dark. When the input side is fully 
illuminated, the liquid crystal rotates the polarized light 90° from \
a 
horizontal direction to a vertical direction. Ninety nine percent 
(99%) of the light entering the ILA® assembly is reflected and 
passes through the prism resulting in a white screen.  
The modulated high-intensity light is reflected back out of the 
output side of the ILA® assembly, through the Prism and the 
Projection Lens and onto the screen. (see Figure 2-19). 
 
Figure 2-19.   Simplified Image/Optical path. 
Model 220 Service Manual  2-61  
						

							Chapter 3---Service Adjustments 
3.0  Service Adjustments 
Contents 
3.1   Arc Lamp Focus........................................................................\
...............3-1 
3.2   Arc Lamp Current Setting........................................................................\
3-5 
3.3   Electronic Module Tilt-up........................................................................\
.3-5 
3.4   ILA® Back Focus........................................................................\
.............3-6 
3.5   CRT Mechanical Focus........................................................................\
....3-7 
3.6   CRT Rotation........................................................................\
...................3-9 
3.7   CRT Electronic Focus........................................................................\
......3-9 
3.8   ILA® Overlap........................................................................\
....................3-10 
3.9   Jumper Settings........................................................................\
...............3-11 
3.9.1   Front/Rear Jumper Settings..........................................................3-11 
3.9.2   Inverted Vertical Jumper Settings..................................................3-12 
3.10 Vertical and Horizontal Size Settings.......................................................3-13 
3.11 Software Updating........................................................................\
...........3-14 
3.12 Cleaning Lens, ILA® assemblies, and Mirrors.........................................3-18 
 
This chapter details adjustment procedures required to maintain the Mode\
l 220. 
Refer to Figures 4-1 and 4-11 to locate the assemblies and components. A\
 tool 
list, required to perform adjustments, is in Chapter 1. 
CAUTION! Before performing procedures in this chapter, review the chapter 
on Safety at the beginning of this manual. 
  WARNING!!!  When performing procedures in this 
chapter that require the projector covers to be removed, wear high volta\
ge 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. 
3.1 Arc Lamp Focus 
The Arc Lamp may need to be refocused whenever an Arc Lamp is 
replaced. The Arc Lamp may also become defocused or 
misaligned from physical shock to the projector. In these instances 
the first condensing lens may have to be adjusted. 
1.   Select and view Red, Green, and Blue. 
2.   Select Test Pattern 4, Flat Field. 
3.   Use the right/left arrow keys on the remote control and adjust 
the Flat Field to 0%. 
Model 220 Service Manual  3-1  
						

							Chapter 3 Service Adjustments 
4.   From the System menu, select Maintenance, then select #3, 
ILA® Bias. Record the ILA® Bias present value (the Green 
bias will be readable). This bias value will be returned to when 
this procedure is complete. Only the Green value needs to be 
recorded. Red and Blue return to their original values when 
Green is reset. 
5. Use the right arrow key to increase the ILA® Bias so the Flat 
Field turns white. If the screen begins to turn from white to a 
yellow-tinge, use the left arrow and adjust the bias back until an 
all white flat field is observed. The flat field screen must be 
white to properly perform the arc lamp focus. 
6. Defocus the Arc Lamp by turning the Z-axis Focus Adjust 
Screw (see Figure 4-4) until a bright, circular area (Figure 3-3) 
is achieved. This is the Arc Lamp’s “hot spot.” The sides, top,\
 
and bottom areas will taper off in brightness. When performing 
defocus, do not attempt to narrow the circle too much. Try to 
obtain a uniform circular area. 
NOTE: The Model 220 uses an integrated lamp/reflector system. 
Normally no adjustment is required, except for Z-axis focus, when 
replacing the arc lamp. It is not possible to predict how much 
variation there will be from lamp to lamp. The adjustment 
procedure below for the first condensing lens should be performed 
only when the location of the hot spot on the screen is extremely 
offset from the center of the screen. If the hot spot is not 
extremely off center, skip steps A through G. CAUTION! This 
procedure should not be undertaken unless absolutely necessary. 
A. Turn projector power off at the remote.  
B. Wait for the Arc Lamp cooling fans to stop and turn the 
circuit breaker on the rear panel off. 
WARNING!!! Some components under the Optical Shield, 
especially the First Condensing Lens and nearby components, 
are still hot! Before removing the Optical Shield (Step C below) 
wait at least 10 minutes for these components to cool down. 
C. Remove the Optical Shield (see Figure 4-1) by removing the 
four screws holding it. Place the Optical Shield in the 
manner shown in Figure 3-2 so that it blocks the light from 
the lamp but still allows enough room to adjust the 
condensing lens Retainer Ring. 
D. Using a 7mm open end wrench, slightly loosen (about ½ turn 
or so) the 3 nuts that hold the First Condensing Lens 
(Figure 3-1). Do not loosen these screws too much or it 
becomes more difficult to perform small adjustments. 
3-2 Model 220 Service Manual  
						

							Chapter 3---Service Adjustments 
 
       Vertical 
Adjustment 
   Horizontal 
Adjustment Slightly 
loosen these 
three screws 
Figure 3-1.  First Condensing Lens (rear of Arc Lamp). 
WARNING!!! The next step reapplies power to the projector. 
Dangerous light exists in the mirror area where the Optical Shield was removed. 
It is crucial that hands and other parts of the body be kept away from t\
he Arc 
Lamp light beam. Severe burns can result from even short exposures to the light 
beam. Do not allow anyone near the projector unless they are wearing safety 
goggles of at least X5 strength. Do not look directly at the light beam even 
with safety goggles! 
 
Light beam coming from 
First Condensing Lens 
is extremely intense and 
hazardous. Keep hands 
and other objects away. 
Optical Shield 
Figure 3-2.   Optical area with Optical Shield removed. 
E. Put on safety goggles now! 
Model 220 Service Manual  3-3  
						

							Chapter 3 Service Adjustments 
F. Reapply power to the projector. 
G. CAUTION! The First Condensing lens may still be hot! 
Using a small, flathead screwdriver, adjust the horizontal or 
vertical screw (Figure 3-1) on the First Condensing Lens 
Retainer Ring to center the hot spot on the screen. 
H. Retighten the 3 retainer ring screws (Figure 3-1). 
7. Adjust the focus screw for overall brightness from the center to 
the edges with minimum rolloff. NOTE: Rolloff is the gradual 
difference in brightness from the center of the screen to the 
edges. Ensure the bright area extends to the edges of the 
screen but not over the edges. If possible, use a light meter to 
perform this step. If using a light meter, try to achieve a rolloff 
of 2:1 but no more than 4:1 to the screen corners. The darker 
areas in each of the corners should be balanced evenly. 
8. When the Arc Lamp is focused over the entire screen area, 
reset the Green ILA® bias to original value noted in step 4. 
 
Figure 3-3.   Arc Lamp “Hot Spot” (whitest area) is off-center vertically and 
horizontally. Adjust to center the “hot spot”. 
 
 
 
3.2 Arc Lamp Current Setting 
The Arc Lamp current must be set whenever an Arc Lamp or Arc 
Lamp Power Supply is replaced. Routinely recheck current about 
3-4 Model 220 Service Manual  
						

							Chapter 3---Service Adjustments 
every 500 hours of operation. This procedure is performed using a 
DVM and a clamp-on type current meter such as AMPROBE 
Model AC/DC 1000 or equivalent.  
To perform the Arc Lamp Current Setting: 
1. Verify that power is off to the projector, or turn power off with 
the remote (it is not necessary for the circuit breaker to be off).  
2. Place a DVM (set to read up to 200VDC) across the Arc Lamp 
± terminals (refer to Figure 4-4 for DVM location).  
3. Turn projector power on at the remote and circuit breaker. 
4. Place the clamp-on current meter around the hot lead (white) 
that goes from the Ignitor to the Arc Lamp and measure the 
current going to the lamp. 
5. Multiply the results from the DVM and the clamp-on current 
meter together to get lamp power. The resulting power should 
be 900 watts. 
 
Figure 3-4.  Zoom view of ALPS aperture. 
6. If the result is not 900 watts, adjust the current adjust pot on the 
ALPS (Figure 3-4 shows the current adjust pot locatlion within 
the ALPS aperture. See Figure 4-4 for the aperture location). 
CW=increase, CCW=decrease. If increasing, notice that the 
Arc Lamp voltage from Step 2 may decrease slightly. Adjust the 
trimmer pot until power is 900 watts. CAUTION! Make 
adjustments in small increments and do not adjust beyond 920 
watts or damage to the equipment may occur. 
3.3 Electronic Module Tilt-up 
1. Remove the rear cover (Section 4.2). 
2. Release the clasp on the left side of the electronic module (turn 
CCW and pull out). 
3. Pull out the release pin on the rear-right side of the electronic 
module to tilt it up. Tilt the electronic module up to a vertical 
position. 
4. Ensure the holding pin locks the electronic module in place. 
Model 220 Service Manual  3-5