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DRC Block
Overview
The DRC Block located on the BR board is a line doubling and pattern
recognition system used to quadruple the number of pixels displayed on
the screen. It changes the standard 480I signal to a 960I format. This
means that our horizontal scan rate is now doubled to 31.5KHz.
Inputs
The BR board which contains all the DRC circuitry is a daughter board
that plugs into the A board. All video to be displayed as the main picture
is routed through BR board. This circuit cannot be disabled. The only
time the video is not derived from the BR board is when a Twin-View
feature such as Channel Index or Picture and Picture is used.
The BR board receives three component video signals. The M-Y, M-B-Y
and M-R-Y signals enter the board at CN302/10, 8 and 6, respectively.
These signals are also referred to as Y, U and V. Two other inputs are
necessary; they are vertical and horizontal sync. They enter CN302/4 and
2 as M-VD and M-HD. The HD signal is used to phase sync a 13.5MHz
clock using IC466 Sync Shift and IC303 13.5 MHz Clock. This signal is
used to clock IC306 3 Channel 8-Bit ADC and IC305 TBC.
The component video signals are input to IC306 3 Channel 8-Bit ADC.
This IC outputs 8 bits of Y and 8 bits of C information. These outputs are
input to IC305 TBC. This IC is a Time Base Corrector that removes any
jitter present in the signals. This IC outputs 8 bits of Y and 8 bits of C
information. It also outputs a sync signal that is used to phase lock IC301
54 MHz Clock.
DRC Processing
The 8 bits of Y and 8 bits of C are applied to IC462 Up Converter. The Y
signal is also applied to IC644 Memory. This IC transfers data between
IC645 Memory and IC462 Up Converter. IC462 breaks the data into sev-
eral data streams and outputs them into IC463 Up Converter. Two clocks,
13.5MHz and a 27 MHz, sync this IC. IC463 processes these data streams
and outputs two sets of Y and C data. These data streams are input to
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IC304 Up Converter along with 54 and 27 MHz clocks. The processing
done by IC462, IC463 and IC304 converts the video signals from normal
NTSC to a near HDTV-like equivalent.
Outputs
IC304 Up Converter outputs three component signals to CN301. These
signals are output from CN301/2, 4 and 6 as RC-Y, RC-B-Y and RC-R-Y.
This IC also outputs a RC-VD signal at CN301/8 and a RC-HD signal at
CN301/10. The RC-HD signal is a 31.5KHz horizontal sync signal.
There are also two inputs at CN301/13 and 14 called NomY and BRMI.
This signals are inputs that control the amount of vertical enhancement in
the signal. This is controlled using the DRC Mode selections in the cus-
tomer video menu. The table below shows the voltages at these pins for
each DRC Mode.
DRC Mode
BRMI
High
0 Volts
5 Volts
Low
5 Volts
Game
Troubleshooting
At this time troubleshooting of the BR board should be limited to resoldering
and board replacement. Troubleshooting is nearly impossible because of
the lack of extender cables. DRC problems typically result in a solarized
or blocky picture in the main picture. If your picture is distorted, switch the
set to the Picture and Picture mode. If you problem clears up then you
should replace the BR board.
NomY
0 Volts
0 Volts
5 Volts
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Table of Contents
Troubleshooting
