Hughes Model 230 Projector Service Manual

							Chapter 2---System Description
Model 230 Service Manual2-9
Voltage: 20 to 23 VDC to maintain the arc lamp ON.
Current: 55 to 70 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 constant 20-23 volts and 55-70 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 230
projector.
The following functions are provided by HVPS:
•  Phase locked loop circuit for synchronization to the horizontal sync
•  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. 
						

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2-10Model 230 Service Manual
ARC GND
G2 SUPPLY
G1 SUPPLY 
 /H V  O K    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 S
R ANODE   J58-1
G ANODE  J59-1
B ANODE  J60-1
T O   C R T S VIA VAB
  H PARABOLA
FROM CD BOARD
  V PARABOLA  +80V
FROM LVPS
 +15V
  -15
 /HV ENA (/VA_OK)
  H VPS_SYNC
FROM  RTG
J45
5 11
J44
J45
13 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
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 
						

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Model 230 Service Manual2-11
ARC_GND Return (ground) line for the CRT anodes
CONVERGENCE/DEFLECTION PCB
INPUTS DESCRIPTION
H_
PARABOLAHorizontal parabola for use by the dynamic focus amplifier
V_
PARABOLAVertical 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
CRTS
OUTPUTS DESCRIPTION
RED_ANODE
GRN_ANODE
BLU_ANODEAnode supply for the three CRTs. About 25 KV
RED_FOCUS
GRN_FOCUS
BLU_FOCUSFocus 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 230
Projector are:
•  Graphics Enhancer 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. 
						

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2-12Model 230 Service Manual
•  Optional HDTV VIC used for High Definition Television.
•  Optional Quad Standard Decoder VIC used for NTSC, PAL SECAM and
other composite sources.
Graphics Enhancer RGB Video Input Card
The Graphics Enhancer RGB VIC is located at the rear of the projector. It has
five BNC inputs. It provides the RGB and sync interface for the 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
RED_VIC
GRN_VIC
BLU_VIC
/SEL_VIC RED
GREEN
BLUE
IIC_CLK
IIC_DATA
+5.1V_STBY
+5.1V
+15V
-15VB2
B4
B6
12* B8
B13
A13
A16
B16
B15
B14
*Pin callouts are to P12, P14, 
or P18, depending on which
VIC slot is being used.
GRAPHIC
ENHANCER
H_VIC
B10V_VIC
A1      GND
A2      GND
A3      GND
IIC HORIZ
VERTIIC_INT
A12
Figure 2-6.  Graphics Enhancer RGB VIC I/O
Video and sync interface for red, green and blue
This 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 230 Projector.
IIC serial bus interface section
The Graphics Enhancer 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: 
						

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Model 230 Service Manual2-13
Table 2-2.  Graphics Enhancer RGB VIC IIC communication
I/O Bits Information Description
I 1 /SEL_CH Select line for the Graphics Enhancer 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.
The Graphics Enhancer 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.  Graphics Enhancer RGB VIC I/O signals
PROJECTOR INPUTS
INPUTS DESCRIPTION
RED
GREEN
BLUEVideo 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_VICVideo signals. about 0.7 to 1 VPP
H_VIC Horizontal or composite sync signals
V_VIC Vertical sync signals 
						

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2-14Model 230 Service Manual
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.
+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. 
						

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Model 230 Service Manual2-15
RED_VIC
GREEN_VIC
BLUE_VIC
H_VIC
V_VIC
IIC/SEL_VICIIC_CLK
IIC_DATA
IIC_INT
+5.1Vstby
+5.1V
+15V
-15V
4:1 
VIDEO
MUX
and
BUFFERS
RED_CH1
RED_CH2
RED_CH3
RED_CH4
GRN_CH1
GRN_CH2
GRN_CH3
GRN_CH4
BLU_CH1
BLU_CH2
BLU_CH3
BLU_CH4
HOR_CH1
HOR_CH2
HOR_CH3
HOR_CH4
VER_CH1
VER_CH2
VER_CH3
VER_CH4
Figure 2-7.  Quad Input RGB VIC
The same functions performed by the Graphics Enhancer RGB VIC are
performed by the Quad Input RGB VIC. The description of operation and pinouts
are the same as the Graphics Enhancer RGB VIC. One of four LEDs indicates
which of the four RGB inputs is currently active.
HDTV YPbPr VIC
This color decoder video input card (YPbPr_VIC) is located on the back side of
the projector and contains three BNC input connectors which can be used for
two different inputs, YPbPr or GBR. This board converts these color component
signals to RGB type video signals.
The following functions are provided by YPbPr_VIC:
•  Video input and output buffers
•  Conversion of color components signals to RGB video signals
•  Separation of syncs from the Y/G input signal
•  Hue, sharpness, gamma, and color adjustment
•  Selection of RGB input or color component input
• LED indication 
						

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•  IIC serial bus interface
RED
GRN
BLU
HOR
/SELECT Y/G
Pb/B
Pr/R
IIC_CLK
IIC_DATA
+5.1V_STBY
+5.1V
+15V
-15VB2
B4
B6
B8
B12 B13
A13
A16
B16
B15
B14
Pin callouts are to P12, P14, 
or P18, depending on which
VIC slot is being used.
Figure 2-8.   HDTV YPbPr VIC Input/Output Diagram.
This VIC accepts two types of video signals, color components (YPbPr) and
RGB signals. In either case the output of this VIC is RGB type signals. If the
inputs are color components they will be converted to RGB type signals.
The selection between color component input mode and RGB input mode is
controlled by an input. This input is controlled by the System Controller Board via
the IIC serial bus interface.
LED indication
There are two LEDs on this VIC. The RGB LED glows when the YPbPr_VIC is
selected and is in RGB input mode. The YPbPr LED glows when the YPbPr_VIC
is selected and is in YPbPr input mode. Both LEDs are off when the YPbPr_VIC
is not selected as the input to projector. Only one LED can be on at one time.
IIC Interface
The YPbPr_VIC is controlled by the serial bus interface. The IIC bus comes from
the System Controller Board through the Backplane Board. All required
adjustments for this board are provided via the IIC serial bus interface. The
information transferred over the IIC bus is indicated below (I = input to
YPbPr_VIC, and O = output of YPbPr_VIC). The selection of this VIC is
accomplished through the IIC control bus which provides the /SEL_VIC signal. 
						

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Model 230 Service Manual2-17
Table 2-4.  HDTV VIC IIC Interface
I/O BITS INFORMATION DESCRIPTION
I 1 /SEL_YPbPr Selects YPbPr input mode for the
YPbPr_VIC.
Low = Selected YPbPr input mode.
I 1 /SEL_RGB Selects RGB input mode for the YPbPr_VIC.
Low = Selected RGB input mode.
I 8 GAMMA Data for adjustment of Gamma correction
I 8 COLOR Data for adjustment of color
I 8 HUE Data for adjustment of hue
I 8 SHARPNESS Data for adjustment of sharpness
O 4 VIC_ID VIC identification lines. 0001 for YPbPr_VIC
O 1 VIC_MODEL Revision of the YPbPr_VIC.
O 1 /YPbPr_OK YPbPr_VIC status line. Low = operational
YPbPr_VIC
The HDTV YPbPr_VIC I/O
This section provides a comprehensive description of the inputs to and outputs
from the YPbPr_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 YPbPr_VIC, output refers to an output from the YPbPr_VIC.
Table 2-5.  HDTV VIC Signals
PROJECTOR INPUTS
INPUT DESCRIPTION
Y/G
Pb/B
Pr/RVideo input signals-about 0.7 to 1 VPP
VIDEO PROCESSOR BOARD
OUTPUT DESCRIPTION
/SELECT Selection indicator for VIC. Low indicates the selected YPbPr_VIC.
RED
GRN
BLUVideo signals. about 0.7 to 1 VPP 
						

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HOR Composite horizontal / vertical  sync signal
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 YPbPr_VIC.
OUTPUTS DESCRIPTION
/IIC_INT IIC interrupt line. YPbPr_VIC does not initiate any  interrupt
LOW VOLTAGE POWER SUPPLY
INPUTS DESCRIPTION
+5.1 V +5.1 V supply for use by  YPbPr_VIC.
+15 V + 15 V supply for use by  YPbPr_VIC.
-15 V -15 V supply for use by  YPbPr_VIC.
Interlocks and protection
Inputs:
None
Outputs:
None
Quad Standard Decoder VIC
The Quad Standard Decoder VIC is composite and S-Video interface. It contains
three BNC input connectors for Composite Video and S-Video (luminance and
chrominance). This decoder VIC converts these color component signals to
RGBHV type video signals.
The following functions are provided by the Quad Standard Decoder VIC:
•  Select input source-Composite or S-video
• Select standard-AUTO/NTSC/PAL/SECAM/4.43NTSC
•  Conversion of composite and S-video signals to RGB video signals
•  Separation of syncs from the input signal
•  Tint, sharpness, and color adjustment
•  LED indication of Composite or S-video
•  IIC serial bus interface