Projector Service Manual
Table Of Contents
- DECLARATION OF CONFORMITY
- BZSAFE.PDF
- CH1INTRO.PDF
- CH2SYSDE.PDF
- Functional Descriptions
- Contents
- Cover and Base
- External Power Requirements
- Electronics Systems Overview
- System Power
- Card Cage
- Circuit Boards
- Raster Timing Generator Board (RTG) p/n 100568
- Sync Generator
- Sync Detector and Selector
- Serration and Equalization Lockout
- Phase Locked Loop
- VSYNC Detector, Field Separator, and Mux
- Adjustment Counters
- Serial Communication
- Raster Timing Generator I/O
- Interlocks and Protection
- Horizontal Deflection Board P/N 102523 (HDB)
- Vertical Oscillator
- Horizontal Phase Locked Loop
- Horizontal Centering
- Horizontal Power Supply
- Flyback Switching
- Geometric Correction
- Output Section
- Horizontal Sweep Failure Detection
- Serial Communication
- Horizontal Deflection Board I/O
- Interlocks and Protection
- Vertical Deflection Board P/N 102521(VDB)
- Vertical Preamps
- Vertical Amplifiers
- Sweep Failure Detection
- Side Pincushion and Keystone Correction
- Horizontal Linearity Correction
- Top and Bottom Pincushion and Keystone Correction
- Correction Amplifiers
- Serial Communication
- General I/O
- Interlocks and Shutdowns
- Video Processor Board P/N 104672 (VPB)
- Decoder
- Video/Sync Mux
- V & H Sync Strip
- SG Sync Strip
- B, G, and R Brightness and Contrast Amplifiers
- On-Screen Switch
- Gamma Correction
- Switch Logic and Video Enable
- RGB Sensitivity and Threshold Amplifier
- ILA® Bias
- Dynamic Focus Amplifier
- Serial Communication
- General I/O
- Interlocks and Protection
- Video Amplifier Board P/N 103567 or 103774 (VAB)
- Video Signal
- Failure Detection
- Beam Current Sense
- DC Restore
- Arc Protection
- Blanking
- Enable Circuit
- Focus
- Filament Supply
- General I/O
- System Controller Board P/N 104668 (SCB)
- General Functional Description
- CPU
- Working and Compressed Memory
- Expanded Memory
- Correction Address Generator
- DACs
- DSP
- Overlay Memory
- Overlay Address Generator
- Overlay Interface
- LED Display Buffers and Logic
- RS232 Interface
- IR Interface
- IIC Interface
- Serial Interface
- General I/O
- Backplane Board p/n 100571
- Optical Section
- Image Light Amplifier
- Functional Descriptions
- CH3ADJST.PDF
- CH4MAINT.PDF
- Maintenance Remove/Replace)
- Contents
- Introduction
- Projector Covers
- Ventilation Filters
- Arc Lamp Assembly
- System Power Supply
- Electronics Module
- Cathode Ray Tube (CRT)
- Video Amplifier Board (VAB)
- CRT Yoke
- High Voltage Power Supply (HVPS)
- Card Cage (Printed Circuit Boards)
- Image Light Amplifier Assembly
- Projection Lens
- (SCB) Socket Battery Replacement
- Recommended Spares
- Maintenance Remove/Replace)
- CH5TRBSH.PDF
- HGLOSS.PDF
Chapter 2—Functional Descriptions
2-56 Model 330. 340SC, and 370SC Service Manual
Beam Current Sense
The cathode current is sensed at the output of the video amplifier, then filtered
and amplified so that the output is a 1mV/1uA signal averaged over several
horizontal lines (the number of lines depending on the horizontal frequency). This
current sense signal is then sent to the VPB as the signal BEAM.
DC Restore
The DC Restore function is accomplished on the Video Amplifier Board when
commanded by the CLAMP signal from the VPB. When the CLAMP signal
arrives, the video signal has the offset values (Brightness and Threshold) removed
so that they will not be changed by the DC Restore circuit. The CLAMP signal
causes the output voltage to be sampled and compared to a reference. The
difference is sent to the input of the video amplifier to set the new black level for
the duration of the next horizontal line.
Arc Protection
The Arc Protection Circuit functions to drain off any energy that arrives at the
Video Output Amplifier board due to arcs on the cathode or grids. The arc energy
is suppressed by sending it directly to the HVPS chassis via the Arc Ground
terminal on the
board.
Blanking
The Blanking circuit operates by using the BLANKING signal from the VPB. The
BLANKING signal causes an amplifier to drive an AC coupled pulldown of
GRID1. G1 voltage is normally -81V but will be pulled down to -111V during the
blanking interval. The cathode voltage is unaffected by blanking.
Enable Circuit
The Enable circuit is controlled by the /ENABLE signal from the VPB. The
/ENABLE signal, when pulled high, causes both GRID1 and GRID2 to be pulled
low: G1 is pulled from nominal -81V to the disabled value of -200V, G2 is pulled
from its usual value of between +800V to +1200V to its disabled value of +15V.
Focus
The FOCUS voltage is a pass through from the HVPS to the CRT. It is not in any
way modified by the VOB.
Filament Supply
For the CRT Filament supply, 6.3Vdc from the System PS is simply filtered and
sent to the CRT.