Hughes Jvc 220 Projector Service Manual

							Chapter 2---System Description 
2.3   Electronics System 
2.3.1 General Description 
The Model 220 Electronics System includes nine printed circuit 
assemblies. They provide all the controlling voltages and signals 
to adjust and correct picture settings, geometry, convergence, and 
shading (see Chapter 4 of the User’s Guide). The Electronics 
System also controls video and sync input signals, LED displays 
on PCBs at the rear and side of the projector, two RS-232 
communications ports, and two IR receivers for remote control of 
the projector. 
The descriptions in this portion of the manual are based on an 
overall Electronics System block diagram and simplified block 
diagrams for each of the nine printed circuit assemblies. The 
diagrams and descriptions serve two purposes; first, to provide the 
technician with an overall grasp of how the system works and how 
each assembly works with other assemblies in the system, 
second, to provide the technician with enough information to 
troubleshoot to the assembly level, if needed.  
Figure 2-2 provides an overall System Block Diagram to show how 
the Optical System, Arc Lamp, and Electronics System combine to 
provide the bright screen image. 
VIDEO INPUTCARDS
SCAN REVERSALBOARD
VIDEO PROCESSORBOARD
SYSTEMCONTROLLER BOARD
RASTER TIMINGGENERATOR
CONVERGENCE DEFLECTION BOARD
HORIZONTALVERTICAL DEFLECTION BOARD
LINEFILTERACINPUT
ARC LAMPPOWER SUPPLY
LOW VOLTAGEPOWER SUPPLY
VIDEO AMP
G2
ELECTRONICS MODULE
IGNITOR
TO CRTS
FOCUS
HIGH VOLTAGEHIGH VOLAGEPOWER SUPPLY
CRTS
RELAYLENSES
PROJECTIONLENS
OPTICS MODULE
ILA’S
DICHROICMIRRORASSEMBLY
UV FILTER/SECOND CONDENSING LENS
COLD MIRROR/IR FILTER
ARC LAMP
BACKPLANE 
DIFFUSER
FIRSTCONDENSINGLENS
 
Figure 2-2.   Model 220 System Block Diagram 
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							  Chapter 2---System Description 
2.3.2   Power Supplies 
The Model 220 includes three power supply assemblies. 
• Low Voltage Power Supply 
• Arc Lamp Power Supply 
• High Voltage Power Supply 
Low Voltage Power Supply (LVPS) 
P75
P76
1
3
5
1-7
8
9
10
11
12
13
14
15
16
17
18
To P8 on
BackplaneAC
INPUTLine
Earth
Neutral
LV Ret
/LV_ENA
/LV_OK
+24v Fans
+5.1v STBY
+5.1v
+6.2v
+15V
-15v
+80V
/COVER_ON
/FAN_ENA
 
Figure 2-3.   LVPS Input/Output Diagram 
Main Functions: 
• Provide all the low voltages needed by the projector. 
• Provide standby power when the projector is OFF. 
• Provide power for all cooling fans. 
Inputs: 
The Low Voltage Power Supply receives AC input power directly 
from the power source. The input range is from 100 VAC to 240 
VAC, at 50 or 60 Hz.  
/LV_ENA: Enabling signal from the System Controller Enables the 
LVPS when the System Controller receives a Power On 
command. 
/FAN_ENA: From System Controller. Enables the +24v standby 
voltage for the projector fans. 
/COVER_ON: Cover interlock signal. Indicates both covers in 
place. Enables the non-standby outputs. 
Outputs: 
+ 5.1VDC Main 
+ 5.1VDC Standby 
+ 6.2VDC 
± 15VDC 
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							Chapter 2---System Description 
+ 24VDC 
+ 80VDC 
/LV_OK: When /LV-ENA is enabled, this diagnostic signal 
indicates to the System Controller the status of the non-standby 
supply (all outputs working or not working). 
Operation: 
The main power is filtered via the input filter to prevent radiation 
from escaping back to the power line. From the line filter, AC 
power is fed into the Low Voltage Power Supply module where AC 
is rectified, filtered, and compensated for power factor correction. 
The +5.1V Standby is on whenever AC power is connected to the 
projector and the circuit breaker on the rear panel is in the On 
position. The +24V standby power for the fans turns on when the 
/FAN_ENA signal is received from the System Controller (this 
turns off in 5-8 minutes if power is not turned on by the remote 
control or a PC). All other voltages supplied by the LVPS are 
activated when power is turned on at the remote or PC. These 
include +5.1V for digital components, +6.2V for CRT filaments, 
±15V for analog circuits, and the +80V supply which is used by the 
High Voltage Power Supply, Video Amplifier PCB, and the 
Horizontal/Vertical Deflection PCB. 
Arc Lamp Power Supply (ALPS) 
P71P74
135
ACINPUTLineEarthNeutral
P72
123
To P9 onBackplane
456
GND/LAMP_LIT/LAMP_OK
/LAMP_ENA/COVER_ONGND
LAMP_OUTLAMP_RET
P73
LAMP_OKGND
12
12
To LampModule, J74
To LampModule, J74
 
Figure 2-4.  Arc Lamp Power Supply, Block Diagram 
Main Functions: 
• Provides ignition power to turn the Xenon Arc Lamp ON. 
• Provides steady state power to maintain the lamp ON. 
Inputs: 
The Arc Lamp Power Supply receives AC input power directly 
from the power source. The input range is from 100-240 VAC, at 
50 or 60 Hz. 
/LAMP_ENA: From System Controller. Turns on the ALPS. 
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							  Chapter 2---System Description 
/COVER_ON: Cover interlock signal. Indicates both covers are in 
place.  
/LAMP_OK: Tells the ALPS that the lamp is installed, the 
temperature is within limits, and the lamp cooling blower is 
working. 
Outputs: 
+140 VDC boost voltage to the Laser Power Supply. 
Voltage: 18 to 25 VDC to maintain the arc lamp ON. 
Current: 45 to 50 amps to maintain the arc lamp ON. 
LAMP_OUT: Lamp output voltage, positive. 
LAMP_RTN: Lamp return. 
/LAMP_LIT: Signal to SCB that the lamp is lit. 
Operation: 
Two signals (/COVER_ON and /LAMP_OK) are required in order 
for the arc lamp to light. /COVER_ON from the cover interlock 
switches tells the Arc Lamp Power Supply that the covers are in 
place and the interlock switches are pressed down. /LAMP_OK 
informs the System Controller that the lamp is installed (a 
mechanical switch activates when the lamp is installed) The 
System Controller then sends the /LAMP_ENA signal to the ALPS. 
The /LAMP_ENA signal turns on the ALPS. 
The Arc Lamp Power Supply then provides the +140 VDC boost 
voltage to a spark gap and high voltage transformer which steps 
up the voltage to approximately 32KV and ignites the Xenon Arc 
Lamp. After the Arc Lamp is lit, it is maintained on by the ALPS at 
a steady 20 volts and 47.5 amps. The /LAMP_LIT signal output 
informs the System Controller if the lamp is lit or not. 
The Arc Lamp Power Supply is electrically and magnetically 
shielded to prevent noise or disturbances in the CRTs or other 
circuitry.  
High Voltage Power Supply (HVPS) 
The High Voltage Power Supply (HVPS) is located on top of the 
LVPS on the right side of projector ( as viewed from rear). This  
 
 
supply provides the anode, focus, and screen voltages required 
for the three CRTs in the Model 220 projector. 
The following functions are provided by HVPS: 
• Phase locked loop circuit for synchronization to the horizontal 
sync 
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							Chapter 2---System Description 
• Generation of anode voltages (25 KV) for all three CRTs 
(RGB) 
• Generation of focus voltage (G3) for all three CRTs (RGB) 
• Generation of screen (G2 supply-Black Level) voltage for all 
three CRTs 
• Generation of G1 supply (Blanking) voltage  
• Dynamic focus amplifier using H and V parabolas 
• External ON/OFF and generation of /HV_OK signal 
The High Voltage Power Supply I/O diagram (Figure 2-5) and the 
list of inputs and outputs (Table 2-1), provide an understanding of 
the operation of the HVPS to allow the technician to perform 
module level troubleshooting. 
ARC GND
G2 SUPPLY
G1 SUPPLY 
 /HV OK   T O   C R T S  
 V I
 A  
 V A B
R FOCUS  J58-1
G FOCUS   J59-1
B FOCUS  J60-1
T O   C R T
 SR ANODE   J58-1
G ANODE  J59-1
B ANODE  J60-1
T O   C R T S VI
A VAB
  H PARABOLA
FROM CD BOARD
  V PARABOLA
  +80V
FROM LVPS +15V
  -15
 /HV ENA (/VA_OK)
  H VPS_SYNC
FROM  RTGJ45
5
11
J44
J45
1
3
14
8
9
10
12
6
13
(From VPB)
HIGH
VOLTAGE
POWER
SUPPLY
 
Figure 2-5.  High Voltage Power Supply, I/O Diagram 
The HVPS Input/Output  
This section provides a comprehensive description of the inputs to 
and outputs from the HVPS. The I/O descriptions are arranged by 
the source/destination of the signal. The format used is such that 
the assembly communicated with is used as the primary heading 
of each output. Input refers to an input to the HVPS. Output refers 
to an output from the HVPS. In each case the signals direction is 
noted. 
Table 2-1.  High Voltage Power Supply I/O signals 
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							  Chapter 2---System Description 
RASTER TIMING GENERATOR PCB
INPUT DESCRIPTION 
HVPS_SYNC Square wave HCT level with 50 or 33% duty cycle synchronized to 
horizontal sync. 
VIDEO PROCESSOR PCB
INPUT DESCRIPTION 
/HV_ENA The HVPS enable line. A low enable the HVPS (VA_OK from VPB). 
VIDEO AMPLIFIER PCB
OUTPUTS DESCRIPTION 
G1_SUPPLY DC supply about -150 V for driving the G1 of CRTs 
G2_SUPPLY DC supply about 1.3 KV for driving the G2 of CRTs 
ARC_GND Return (ground) line for the CRT anodes 
CONVERGENCE/DEFLECTION PCB
INPUTS DESCRIPTION 
H_ 
PARABOLA 
Horizontal parabola for use by the dynamic focus amplifier 
V_ 
PARABOLA 
Vertical parabola for use by the dynamic focus amplifier 
SYSTEM CONTROLLER PCB
OUTPUT DESCRIPTION 
/HV_OK The high voltage status line. Low = operational HVPS 
LOW VOLTAGE POWER SUPPLY
INPUTS DESCRIPTION 
+ 15V + 15 V for use by the HVPS 
+ 80V + 80 V for use by the HVPS 
- 15V - 15V for use by the HVPS 
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							Chapter 2---System Description 
 
CRTS
OUTPUTS DESCRIPTION 
RED_ANODE 
GRN_ANODE 
BLU_ANODE 
Anode supply for the three CRTs. About 25 KV  
RED_FOCUS 
GRN_FOCUS 
BLU_FOCUS 
Focus voltage for the three CRTs. About 7 KV 
 
Interlocks and protection: 
This section describes the interactions between boards where one 
board may cause others to perform protection functions. 
Input  
A high signal at /HV_ENA shuts off the HVPS.  
2.3.3   Video Input Cards 
The four types of Video Input Cards that can be used with the 
Model 220 Projector are:  
• Standard RGB Video Input Card, which is supplied with each 
projector and is used for RGB standard formats 
• Optional Four Input RGB VIC used in a similar manner as a 
switcher. 
• Optional HDTV VIC used for High Definition Television. 
• Optional Quad Standard Decoder VIC used for NTSC, PAL 
SECAM and other composite sources. 
Standard RGB Video Input Card (RGB_VIC) 
The RGB Video Input Card (RGB_VIC) is located on the back side 
of the projector. It has five BNC input connectors. It provides the 
RGB and sync interface for the Model 220 projector.  
The following functions are provided by the RGB VIC: 
• Video and sync interface for red, green and blue 
• LED indication 
• IIC serial bus interface 
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							  Chapter 2---System Description 
REDGREENBLUEHORIZVERT
RED_VICGREEN_VICBLUE_VICH_VICV_VIC
/SEL_VICIIC_CLKIIC_DATAIIC_INT
+5.1Vstby+5.1V+15V-15V
IIC12
B2B4B6
B8B10
A16B16B15B14
B13A13
A12
Pin callouts are to P12, P14, or P18depending on which VIC slot is used.GND
GND
GND
A1
A2
A3
 
Figure 2-6.  Standard RGB VIC I/O 
Video and sync interface for red, green and blue 
The RGB VIC provides a high bandwidth interface for the three 
color video signals. The video signals are routed to the Backplane 
Board without any distortion or modification. The sync signals 
(horizontal and vertical) are also directly connected to the 
Backplane Board. 
LED indication 
The RGB VIC includes an LED which glows when the board is 
selected (i.e. when the /SEL_CH line is low) as the input for the 
Model 220 Projector. 
IIC serial bus interface section 
The RGB_VIC is controlled by the serial bus interface. The IIC bus 
comes from the System Controller Board through the Backplane 
Board. The information transferred over the IIC bus is indicated 
below (I = input to the RGB VIC, and O = output from the RGB 
VIC). The RGB VIC does not use the interrupt line of the IIC bus 
interface: 
Table 2-2.  Standard RGB VIC IIC communication 
I/O Bits Information Description 
I 1 /SEL_CH Select line for the RGB_VIC. Low = Selected 
RGB_VIC. 
O 4 VIC_ID VIC identification lines. 0000 for RGB_VIC.  
O 1 VIC_MODEL Revision of the RGB_VIC. 
O 1 /VIC_OK RGB_VIC status line. Low = operational 
RGB_VIC. 
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							Chapter 2---System Description 
The RGB_VIC I/O 
This section provides a description of the inputs to and outputs 
from the RGB_VIC. The I/O descriptions are arranged by the 
source/destination of the signal. The format used is such that the 
assembly communicated with is used as the primary heading of 
each group of signals. Those signals are further subdivided into 
inputs and outputs. Input refers to an Input to the RGB_VIC, 
output refers to an output from the RGB_VIC. 
Table 2-3.  Standard RGB VIC I/O signals 
PROJECTOR INPUTS 
INPUTS DESCRIPTION 
RED 
GREEN 
BLUE 
Video input signals. about 0.7 to 1  VPP 
HORIZ. Horizontal or composite sync signal 
VERTICAL Vertical sync signal 
VIDEO PROCESSOR BOARD  
OUTPUTS DESCRIPTION 
/SEL_VIC Select line for VIC. A low indicates the RGB_VIC is selected. 
RED_VIC 
GRN_VIC 
BLU_VIC 
Video signals. about 0.7 to 1 VPP 
H_VIC Horizontal or composite sync signals 
V_VIC Vertical sync signals 
SYSTEM CONTROLLER BOARD 
INPUTS DESCRIPTION 
IIC_CLK IIC clock line. Unidirectional clock line for control of synchronous 
data transfer over the IIC bus interface. 
IIC_DATA IIC data line. Bidirectional serial line for synchronous data transfer 
between system control board and the RGB_VIC. 
OUTPUTS DESCRIPTION 
/IIC_INT IIC interrupt line. RGB_VIC does not initiate an interrupt. 
LOW VOLTAGE POWER SUPPLY 
INPUTS DESCRIPTION 
+5.1 V +5.1 V supply for use by RGB_VIC. 
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							  Chapter 2---System Description 
+15 V + 15 V supply for use by  RGB_VIC. 
-15 V -15 V supply for use by  RGB_VIC. 
+ 5.1 V_stby + 5.1 V stand by supply for use by RGB_VIC. 
Interlocks and protection 
Input:  None 
Outputs:  None 
Quad Input RGB VIC 
The Quad Input RGB VIC consists of four sets of RGBHV inputs 
and operates in a manner similar to a switcher. The four inputs are 
multiplexed so that only one is enabled at a specific time. 
Software selects the desired input channel through the IIC bus 
and ensures that only one RGB VIC is enabled. When one of the 
channels assigned to the Quad RGB VIC is selected, the 
/SEL_VIC line to the Video Processor is enabled.  
RED_VICGREEN_VICBLUE_VICH_VICV_VIC
IIC/SEL_VICIIC_CLKIIC_DATAIIC_INT
+5.1Vstby+5.1V+15V-15V
4:1 
VIDEO
MUX
and
BUFFERS
RED_CH1RED_CH2RED_CH3RED_CH4
GRN_CH1GRN_CH2GRN_CH3GRN_CH4
BLU_CH1BLU_CH2BLU_CH3BLU_CH4
HOR_CH1HOR_CH2HOR_CH3HOR_CH4
VER_CH1VER_CH2VER_CH3VER_CH4
 
Figure 2-7.  Quad Input RGB VIC 
The same functions performed by the Standard RGBHV VIC are 
performed by the Quad Input RGB VIC. The description of 
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