Detailed Description; Pcb-Video-Sub Circuit; Pcb-Video Circuit - Mitsubishi C-6919 Service Manual

The ABL circuit monitors CRT beam current return.
If CRT beam current exceeds the set reference level, the
brightness voltage is limited to control the beam current.
3.2 DETAILED DESCRIPTION
This section contains detailed description of circuit
operation for the Model C-6919 s2rias Color Display
Monitor.
Schematic diagrams attached to this booklet are necessary
to understand the following description.
3.3 PCB-VIDEO-SUB CIRCUIT
This PCB unit contains Video Preamplifier, Sync Separator
and Sync Processor.
3.3.1 Video Preamplifier
This circuit board contains three video amplifiers,
one for each primary color. These three amplifiers, for
the red, green and blue CRT guns, are identical.
Since the three amplifiers are identical, the operation
of one channel (GREEN) is described here.
The three video inputs are wired to BNC Connectors
Located on the rear panel. One termination switch
(SlOl) on the PCB-VIDEO-SUB circuit board provides all
three inputs selection of 75 ohm or high-impedance
termination.
GREEN Video signal enters the monitor at Connector
Sl93 and is terminated by 75n resistor RlOl through
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