Filter
Top Products
Theory of Operation
3–12
1780R-Series Service Manual
Diagram 5 Difference Amplifier & Video Filters
The signal at the output of the Difference Amplifier is distributed to many
internal circuits. Seventy-five-ohm video is provided to the Auxiliary Output and
Picture Monitor BNC connectors. There is an additional current source to
provide bright-up for the selected line(s) on the Picture Monitor Output.
There are four filters that act on the applied video signal (luminance, low-pass,
chrominance, and differentiated step). Their outputs are selected by a saturated
transistor switch. Unfiltered video passes to the switch unaltered for full
bandwidth frequency response. Several other signals can be switched in for
display at this point. They are Alt Demod and Vector R-Y from the vectorscope,
cursor voltages from the Vertical Control Schematic, and the Auxiliary Video
Input.
Overview