Theory of Operation
1735 HD High Definition Waveform Monitor
4–7
Two of the eight video switch inputs are used for the CAL display function. The
0.700 volts at U50, pin 22 is from a precision voltage divider and voltage
reference (series pass regulator). The grounded input at U50, pin 2 is also used
for the no input display when no inputs are selected.
CH1B Invert.
When subtract mode is enabled, the output of amplifier U16, pin 6,
is the difference between CH 1B and the selected channel. When enabled, the
CH 1B invert amplifier (U47) acts as a follower. Its gain (adjusted by R383) and
delay (through filter C131, C144, L10, and L11) match the CH 1B video signal
path through the video switch (U50) and driver amplifier (U38). When CH 1B is
selected and subtract mode is enabled, the null at the output of the difference
amplifier (U16, pin 6) shows the accuracy of this match.
When subtract mode is not enabled, the CH 1B invert amplifier output (U47, pin
6) is an open circuit, grounded through its feedback resistors and through the
terminating resistors of the delay match filter (R365 and R72). The difference
amplifier output (U16, pin 6) is inverted 2X video.
Vertical Position Control and Vertical Gain Control.
The Gain Cell (in U25,
Diagram 5) is used for video channel gain calibration, vertical X5 mag calibra-
tion, front-panel gain cal adjust, and front-panel variable gain.
The vertical level shift is used for vertical positioning. If offsets are enabled,
offset controls are added to the vertical position control. Control signals
2OFFSEL, 3OFFSEL, and BOFFSEL to U27 switch in front-panel offset
controls for CH2 OFFSET, CH3 OFFSET, and CHB OFFSET. Summing
amplifier U28A determines the nominal voltage and range for the VMOVE
control signal for the vertical level shift.
When vertical X5 gain is selected, control signal VERT5X to U30C switches in
R128. When vertical variable gain is selected, control signal VARSEL to U30A
and U30B switches from the front-panel CAL control to the front-panel VAR
control. Summing amplifier U28B determines the nominal voltage and range for
the VSIZE control signal for the gain cell.
Summary of Contents for 070-8462-03
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Page 13: ...Table of Contents viii 1735 HD High Definition Waveform Monitor...
Page 19: ...Preface xiv 1735 HD High Definition Waveform Monitor...
Page 20: ...Getting Started...
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Page 35: ...Installation 1 14 1735 HD High Definition Waveform Monitor...
Page 36: ...Operating Basics...
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Page 179: ...Corrective Maintenance 7 20 1735 HD High Definition Waveform Monitor...
Page 181: ...Repackaging 7 22 1735 HD High Definition Waveform Monitor Figure 7 10 Repackaging...
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