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...

  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...

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...

  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...

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...

  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...

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...

  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...

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...

  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...