9600 Service Manual - gmecorp-usa.com

30 Image System
Anti-Vignetting
A selectable anti-vignetting correction input is provided (TTL active low). This feature
provides parabolic correction in both the vertical and horizontal axis. The amount of
compensation is adjustable up to a minimum of 50% vertically and horizontally over the
circular area equal in diameter to the height of the sensor (6.6 mm). This signal
dynamically boosts the gain of the video amplifier at the periphery of the image without
affecting black level. This is done to accomplish an even shading over the entire area of
the image.
The anti-vignetting signal is sent directly from the Technique Processor PCB to the
Image Function PCB via RS-232 serial communication. The command is received by
receiver U17 pin 9 and output (pin 10) directly to micro-processor U16 pin 17. Once
processed by U16, output latch U6 pin 16 sends the signal to the CCD Camera via
buffer U5 (pins 13 and 12).
Test Pattern
A test pattern has not been implemented at this time. An intermittent problem of a
square black box appearing on the left monitor of the Workstation can be remedied by
cutting pin 6 of U5 on the Image Function PCB, which is the “Test Pattern” output to the
CCD camera.
+24 Volts and DC Common
The +24V for the camera comes directly from the C-Arm +24V power supply PS2. It
passes through the Power Motor Relay PCB P7-7 to P5-1. It can be measured on that
PCB at test point TP1. After leaving the Power Motor Relay PCB, it passes through the
Image Function PCB P2-3 to P3-22 and enters the camera at P1-2.
The DC common connection for the camera is made on the Power Motor Relay PCB. It
leaves that board at P5-2, and is connected to the camera at P1-1 via the Image
Function PCB P2-4 to P3-19.