Hughes Model 230 Projector Service Manual

Chapter 2---System Description
Model 230 Service Manual2-19
R
G
B
/H
/SELECT Comp
Y in
C in
IIC_CLK
IIC_DATA
+5.1V
+15VB2
B4
B6
B8
B12 B13
A13
B16
B15
Pin callouts are to P12, P14, 
or P18, depending on which
VIC slot is being used.
/V
B10
Figure 2-9.   Quad Standard Decoder I/O Diagram.
LED Indication
There are two LEDs on this VIC. The LED on the right side of the board glows
when Composite Video is selected and the LED on the left glows when S-Video
is selected. Only one LED can light at one time.
IIC...

Chapter 2---System Description
2-20Model 230 Service Manual
I TINT Data for adjustment of Hue
I COLOR Data for adjustment of color
I SHARP Data for adjustment of Sharpness
I VTR Selection of VTR mode
O VNR Selection of Video Noise Reduction mode
Quad Standard Decoder VIC I/O
This section provides a description of the inputs to and outputs from the Quad
Standard Decoder VIC. The I/O descriptions are arranged by the
source/destination of the signal. The format used is such that the assembly
communicated...

Chapter 2---System Description
Model 230 Service Manual2-21
LOW VOLTAGE POWER SUPPLY
INPUTS DESCRIPTION
+5.1 V +5.1 V supply for use by The Quad Decoder VIC.
+15 V + 15 V supply for use by the Quad Decoder VIC.
Interlocks and protection
None
2.3.4  Video Processor PCB
The Video Processor Board (VPB) is the bottom-most card (see Figure 5-1) in
the card cage. It is connected directly to the Backplane board through 2
connectors. When an external signal is being received, the VPB provides
Horizontal Sync,...

Chapter 2---System Description
2-22Model 230 Service Manual
B31   RED_VIC#1
B29   RED_VIC#2
B27   RED_VIC#3
B23   GRN_VIC#2
B21   GRN_VIC#3
B19   BLU_VIC#1 B25   GRN_VIC#1
B24  RED_THRESH
B23  GRN_THRESH
B22  BLU_THRESH B25  BLU_SENSB17   BLU_VIC#2
B15   BLU_VIC#3
B13   H_VIC#1
B9     H_VIC#3
B7     V_VIC#1
B5     V_VIC#2B11   H_VIC#2
B3     V_VIC#3
GRN_G2    A20
BLU_G2     A21 
G1_BIAS    A11 RED_G2    A19 
B20  GRN_BEAM
B21  BLU_BEAM
A13  /VA_OK (/HV_ENA) B19  RED_BEAM
A8         +5.1V
A9...

Chapter 2---System Description
Model 230 Service Manual2-23
I RED_G2 Red G2 Control
I GRN_G2 Green G2 Control
I BLU_G2 Blue G2 Control
I WHT_BOOST Gamma correction
I BLK_BOOST Gamma correction
I G1_BIAS G1 bias level
O /VA_OK Issues to SCB that Video Amplifier
is OK
O BEAM_CURRENT Beam current control
O OK_DETECT Issues to SCB that VPB is OK
Video Processor I/O
This section provides a comprehensive description of the inputs to and outputs
from the VPB. The I/O descriptions in Table 2-9 are arranged by...

Chapter 2---System Description
2-24Model 230 Service Manual
BLU_SENS Similar to RED_SENS
RED_THRES Threshold correction information for red. Real time data at
0 Volt to 1 Volt
GRN_THRES Similar to RED_THRES
BLU_THRES Similar to RED_THRES
 I/O DESCRIPTION
IIC_DATA IIC data line. Bidirectional serial line for synchronous data
transfer between SCB and other circuit boards. See detailed
description for list of signals transferred and data direction
IIC_CLK IIC clock line. Unidirectional clock line for...

Chapter 2---System Description
Model 230 Service Manual2-25
GRN_BEA Similar to RED_BEAM
BLU_BEA Similar to RED_BEAM
/VA_OK Issued from the VAB to indicate VAB working properly
OUTPUT DESCRIPTION
RED_VID Red video output. 0 Volt to 1 Volt.
GRN_VID Similar to RED_VIDEO
BLU_VIDE Similar to RED_VIDEO
RESTOR DC RESTORE control signal. When this signal is asserted,
DC level of the video signal is clamped at the proper value
on the VAB.
RED_G2 Red CRT G2 voltage adjust control signal.
GRN_G2 Similar to RED_G2...

Chapter 2---System Description
2-26Model 230 Service Manual
 V_VIC #2  Similar to V_VIC #1
 V_VIC #3  Similar to V_VIC #1
/SEL_VIC  Input signal from RGB VIC board which is used to select
 input video source from VIC #1.
 /SEL_VIC  Similar to /SEL_VIC #1
 /SEL_VIC  Similar to /SEL_VIC #1
LOW VOLTAGE POWER SUPPLY
INPUTS  DESCRIPTION
+ 5.1 volts  Power supply to digital components
+ 15 Volts  Power supply to analog components
- 15 Volts  Power supply to analog components
2.3.5   Video Amplifier
The Video...

Chapter 2---System Description
Model 230 Service Manual2-27
G1 Regulator for three CRTs
The input supply for the G1 grid of the CRTs is G1_SUPPLY and is about -200V.
The VAB regulates this supply to about -80V to -30V. This supply can be
adjusted by the G1_BIAS line. This adjustment provides the brightness control
function. The G1_BIAS signal is an input of the VAB and is generated by the
Video Processor Board. In the event of a failure, such as lack of deflection (a
high on the /SWEEP_OK line), this...

Chapter 2---System Description
2-28Model 230 Service Manual
CRT interface for Focus, heater voltages and ARC ground
The three CRT sockets are part of the VAB. They provide the necessary
interface for the input of the three CRTs. The Focus voltage for each color is
connected directly to the socket of each CRT.
The VAB provides ARC grounds for each CRT which are used to protect against
arcing of the CRT anode supply.
IIC Interface
The VAB does not use the IIC interface. All adjustments are accomplished by...