Hughes Jvc 220 Projector Service Manual

Chapter 2---System Description 
GRN_BEAM Similar to RED_BEAM 
BLU_BEAM Similar to RED_BEAM 
/VA_OK Issued from the VAB to indicate VAB working properly 
OUTPUT DESCRIPTION 
RED_VIDEO Red video output. 0 Volt to 1 Volt. 
GRN_VIDEO Similar to RED_VIDEO 
BLU_VIDEO Similar to RED_VIDEO 
RESTORE DC RESTORE control signal. When this signal is asserted, the 
 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 
 V_VIC #2  Similar to V_VIC #1 
 V_VIC #3  Similar to V_VIC #1 
/SEL_VIC #1  Input signal from RGB VIC board which is used to select 
  input video source from VIC #1. 
 /SEL_VIC #2  Similar to /SEL_VIC #1 
 /SEL_VIC #3  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 
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 output goes to the 
most...

  Chapter 2---System Description 
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 the control lines...

Chapter 2---System Description 
INPUTS DESCRIPTION 
G1_SUPPLY Supply for G1 grid of CRTs. About -200 V 
G2_SUPPLY Supply for G2 (screen) grid of CRTs. About 1200 V 
RED_FOCUS 
GRN_FOCUS 
BLU_FOCUS 
Focus supply for CRTs. about 7 KV 
OUTPUTS DESCRIPTION 
ARC_GND CRT ground (anode supply return line) 
HORIZONTAL/VERTICAL DEFLECTION BOARD 
INPUTS DESCRIPTION 
/SWEEP_OK Deflection detection line. open collector, low = good deflection 
RASTER TIMING GENERATOR BOARD  
INPUTS DESCRIPTION 
BLANKING Blanking...

  Chapter 2---System Description 
 
RED_GRID2 
GRN_GRID2 
BLU_GRID2 
G2 (screen) supply of CRTs. about 600 to 800 V 
OUTPUTS DESCRIPTION 
ARC_GRD Ground of CRTs ( anode supply return line). 
SYSTEM POWER SUPPLY 
INPUTS DESCRIPTION 
+6.2 V +6.2 V supply line (heater voltage). 
+15 V +15 V supply for use by Video Amplifier Board. 
-15 V -15 V supply for use by Video Amplifier Board. 
+80 V +80 V supply for use by Video Amplifier Board. 
Interlocks and protection: 
None 
2.3.6   System Controller PCB 
The...

Chapter 2---System Description 
• Threshold and Sensitivity for shading 
• I/O control 
• Two RS-232 serial interface ports 
• Infrared (IR) remote control interface. Accepts input from front 
or rear IR detectors. 
• A 5-wire JTAG interface port for CPU emulation support. 
• External 3 color system status LEDs. Green indicates normal, 
yellow is standby and red indicates a fault condition. 
• External Service Mode switch (see Figure 5-1). Pressing this 
switch during a power-up sequence brings the...

  Chapter 2---System Description 
P11
B23
B24
B28
B29
B32
B27
B26
B31
B30
Lens Zoom
Lens Focus
/LV_ENA
/FAN_ENA
/LAMP_ENA
/HV_OK
/LV_OK
/LAMP_LIT
/LAMP_OK
P10
B31
B30
A32
A31
A30
A   B20-2021-2122-2223-2324-2425-2526-2627-2728-2829-29
+5.1V stby
+5.1V
+15V-15VGND
ODD_FIELD
SRC_VALID
H_DRIVE_SC
V_DRIVE
B9
B10
B2
B1
B3
RED_OVER
GRN_OVER
BLU_OVER
B18
B17
B16
P10
Y_RED_CONV
Y_GRN_CONV
Y_BLU_CONV
X_RED_CONV
X_GRN_CONV
X_BLU_CONV
B4
B5
B6
B1
B2
B3
BLU_THRES
GRN_THRES
RED_THRES
BLU_SENS
GRN_SENS
RED_SENS
B8
B9...

Chapter 2---System Description 
 
Table 2-11.  System Controller Board I/O signals 
VIDEO PROCESSOR BOARD
I/O DESCRIPTION 
IIC_CLK IIC clock line. Clock line for control of synchronous data transfer over\
 
the IIC bus interface. 
IIC_DATA IIC data line. Serial line for synchronous data transfer of the followin\
g 
data between Video Processor Board and SCB board. I=Input, 
O=Output. 
I     BEAM CURRENT 
I     OK DETECT 
O    RED_CONT 
O    GRN_CONT 
O    BLU_CONT 
O    BRIGHTNESS 
O    RED_G2 
O...

  Chapter 2---System Description 
RASTER TIMING GENERATOR
INPUTS DESCRIPTION 
SOURCE_ 
VALID 
This signal indicates a new source (or valid). A high indicates a vali\
d 
stable signal and low indicates change in input signal. 
ODD_FIELD Square wave with 50 % duty cycle which is low during the odd field 
of an interlace signal. This signal is high for noninterlaced signals. 
280_CLK Square wave signal, 50 % duty cycle, 280 times the frequency of 
horizontal sync. This clock is synchronized to the...