JVC 250 service manual Video Processor PCB - Main Functions, Video Processor PCB - Inputs

Chapter 5---Electronics

5.4Video Processor PCB

Video Processor PCB - Main Functions

!Video signal input and multiplexing

!Sync signal stripping

!Overlay signal multiplexing

!Brightness, Contrast, DC Restore and Blanking

!Video signal gamma correction

!Sensitivity and Threshold signal input and control

!Automatic Contrast, G2, and internal image limiting

Video Processor PCB - Inputs

RGBHV VIC 1,2, & 3 - External image signals from the VICs for red, green, and blue.

/SEL_VIC - input signal from the RGB VIC used to select the input source from VIC #1.

RGB_OVER - from the System Controller PCB, the Menu overlays and internal test patterns for red, green, and blue.

OVERLAY - from the System Controller PCB, switches between internal and external sources.

CLAMP - Pulse signal from the Raster Timing Generator PCB, tells the Video Processor PCB the timing and duration of the DC Restore.

BLANKING - Pulse signal from the Raster Timing Generator PCB, it tells the Video Processor PCB the blanking interval during the scan.

RGB_THRESH - Threshold correction information for red, green, or blue from the System Controller PCB. Real time data at 0-1 V.

RGB_SENS - Sensitivity correction information for red, green or blue from the System Controller PCB. Real time data at 0-1 V.

RGB_BEAM - sense signal proportional to the cathode current averaged over several horizontal lines in the red, green, or blue CRT. The voltage level is + mV/mA.

/VA_OK - signal from the Video Amplifier PCB telling the Video Processor PCB the Video Amplifier PCB is receiving red, green, and blue deflections voltages from the Horizontal Vertical Deflection PCB.

IIC_DATA - IIC data line. Bi-directional serial line for synchronous data transfer between the System Controller PCB and Video Processor PCB.

IIC_CLK - IIC clock line. Unidirectional clock line for control of synchronous data transfer over IIC bus.

Model 250 Service Manual 5-11