Circuit Description
Figure 1 is a block diagram of the VP251 showing
signal flow and the location of front panel controls
and switches. Composite Video and S-Video
inputs are connected to the decoder with AGC
control and converted to Y, R-Y and B-Y signals.
The Y, (Luminance) output from the decoder
enters the input switcher while the R-Y and B-Y
signal enter the Chroma Enhancement block
where the Tint phase can be adjusted when select-
ed in the manual mode. The RGB input signals are
transcoded to Y, R-Y, and B-Y signals and fed to
the input switcher. Component signals are fed
directly to the input switcher.
The input switcher then selects the correct function
and outputs the Y signal to the Luminance Line
Doubler block. The Luminance Line Doubler block
contains the Brightness, Contrast and Freeze con-
trols while the R-Y and B-Y signals enter the
Chroma block where the color level can be con-
trolled along with the Freeze controls. The Line
Doubler Luminance signal now enters the
Luminance Detail and Noise Reduction block
where the functions of Noise Reduction and
Detail Level are controlled.
The Luminance signal from the Luminance Detail
and Noise Reduction block along with the R-Y and
B-Y signals from the Chroma Line Doubler block
feed the output transcoder and are converted
to RGB signals. These RGB signals are buffered
and then sent to both the BNC and monitor
output connectors.
When using the RGB or Component inputs, Sync
is derived from the G or Y input signals unless
sync is provided to the Composite Sync input. The
Composite Sync input will override the sync from
the G or Y inputs. The sync signal then feeds the
VP251 clock generator and is used as a reference
to generate Horizontal Sync, Vertical Sync and
Composite Sync.
Inventory List
1 VP251 Digital Video Processor
1 Installation/Operation Manual
1 Warranty Card
1 Power Cord
5
SYSTEM DESCRIPTION
Caution Notes
Do not connect the VP251 to a Monitor/
Projector not capable of the correct scan
rates. (31.5KHz)
High Voltages are present inside. Opening
the unit will void all warranties.
No user serviceable parts inside.
