Theory of Operation
WFM 601 - Service Manual
3–13
the input amplifiers drive the Transcoder and inputs to the horizontal and vertical
signal processing amplifiers on Diagram 9.
Driven by Input Amplifiers, the Color Difference to RGB Transcoder consists of
three operational amplifiers (U41, U51, and U61) and resistance matrices. The
operational amplifiers and the resistance matrices are signal mixers. Subtraction
and addition of signals is accomplished by presenting the color difference
components to either the inverting or noninverting inputs of the amplifiers. The
resultant signal proportions are shown in Table 3–1. Note that Y is input to the
noninverting input of all three amplifiers (U41, U51, and U61), and that both P
B
and P
R
are input to the inverting input of U41 (the G transcoder). This makes
the output mix for SMPTE format G = Y – 0.3441 P
B
– 0.7141 P
R
.
Table 3–1: Transcoder Signal Mixing
GBR
SMPTE
Green
Y – 0.3441 P
B
– 0.7141 P
R
Blue
Y + 1.772 P
B
Red
Y + 1.402 P
R
The GBR outputs of the operational amplifiers drive clamped amplifiers (U45,
U55, and U65) whose output is always GBR. Offset levels are from the DAC on
Diagram 10. The clamping pulse is from the Coprocessor.
The Transcoder is in operation under all circumstances; however, the Monitor
Output can display either color difference or RGB. When the desired monitor
output is color difference, the Monitor output signal bypasses the Transcoder.
U43, U53, and U63 are switchable input amplifiers driven by either the
Transcoder output or color difference signals output by the Input Selection
amplifiers.
These three identical switch/buffer amplifiers (U81, U82, and U83) drive the
Vertical Input Multiplexer with either GBR or color difference signals. GBR
input is driven by the output of the Transcoder, while the color difference input is
driven directly by the Reconstruction Filters on Diagram 7. Switching signal is
from the Microprocessor on Diagram 14.
Each of the components of the GBR signal, output by the Transcoder, is
compared against limits from the DAC on Diagram 10. The plus limit is set at
735 mV (700 mV + 5%) and the minus limit at –35 mV (0
5% of the 700 mV
total amplitude). When one of the GBR signals exceeds a limit, the comparator
output becomes the Gamut Error signal, which is monitored by the Coprocessor.
In addition, it also drives a brightup circuit (Q76 driving U76), that causes the
RGB Transcoder
Parade Output
Gamut Limit & Sync
Insertion
Содержание WFM601
Страница 4: ...The WFM601 Serial Digital Component Monitor...
Страница 10: ...Contents iv WFM 601 Service Manual Revised Nov 1994...
Страница 14: ...Contents viii WFM 601 Service Manual Revised Nov 1994...
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Страница 233: ...WFM 601 SERIAL COMPONENT MONITOR BNC INPUT BOARDS 1...
Страница 237: ...ECL TO TTL CONVERTER LINE BUFFER RAM WFM 601 SERIAL COMPONENT MONITOR COPROCESSOR 3...
Страница 241: ...2 1 10 4256403 Y DAC DIGITAL HALF BAND FILTER Y DELAY WFM 601 SERIAL COMPONENT MONITOR Y DELAY HALF BAND FILTER DAC 5...
Страница 245: ...Y FILTER Pb FILTER Pr FILTER WFM 601 SERIAL COMPONENT MONITOR Y Pb Pr RECONSTRUCTION FILTERS 7...
Страница 247: ...WFM 601 SERIAL COMPONENT MONITOR TRANSCODERS PIX MONITOR OUTPUTS 8...
Страница 249: ...0 0 0 0 WFM 601 SERIAL COMPONENT MONITOR LIGHTNING VECTOR BOWTIE SWITCHING 9...
Страница 251: ...WFM 601 SERIAL COMPONENT MONITOR CONTROL DACULATOR 10...
Страница 257: ...HORIZONTAL DEFLECTION SWEEP GENERATORS HORIZONTAL SIGNAL MUX HORIZONTAL AMPLIFIER WFM 601 SERIAL COMPONENT MONITOR...
Страница 259: ...ROM MICROPROCESSOR NOVRAM RAM FLASH EPROM BUFFERS RESET ABORT WFM 601 SERIAL COMPONENT MONITOR...
Страница 261: ...OUTPUTS SYNCHRONOUS LINE RATE CONTROLLER SYNC SEPARATOR WFM 601 SERIAL COMPONENT MONITOR DYNAMIC CONTROL 15...
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Страница 271: ...WFM 601 SERIAL COMPONENT MONITOR FRONT PANEL 20...
Страница 282: ...WFM 601 FIG 1 EXPLODED VIEW A1 A2 A3 A4 A4A1 A5 A6 A7 A8...
Страница 290: ...Glossary Glossary 8 WFM601 Serial Component Monitor...
Страница 304: ...A8 DAC Board 671 2676 04 M81119 Page 4 of 4...