1730–Series Theory of Operation
4–29
Q1 and Q2 form an operational amplifier that sets the voltage at the bottom of
the focus divider. The front-panel FOCUS pot determines the voltage at the
bottom of the focus divider. The Center Focus control, R11, is set for optimum
beam focus, as viewed on the CRT, with the front-panel FOCUS control set to
mid range. Once the Center Focus adjustment has been set, adjusting the
front-panel FOCUS control changes the voltage at the bottom end of the divider
and, consequently, the voltage on the CRT focus anode.
The cathode of the CRT is at a –2750 V potential with the grid coupled to the
Z-Axis Amplifier by the grid drive circuit. The grid is approximately 75 V
negative with respect to the cathode. The 200 V p-p sine wave present at the
cathode of CR8 is input to the Grid Drive circuit where it is clipped for use as
CRT control grid bias.
The sine wave from the cathode of CR8 is coupled through R47 to a clipping
circuit consisting of CR5 and CR6. Clipping level for the positive excursion of
the sine wave is set by the CRT Bias adjustment, R58. The negative clipping
level is set by the front-panel INTENSITY control through the Z-Axis Amplifier.
The clipped sine wave is coupled through C11 to a rectifier made up of CR1 and
CR3. The rectified, clipped sine wave is the CRT control grid bias voltage. C9
couples the blanking signal from the Z-Axis Amplifier to the CRT control grid.
DS1 and DS2 limit the CRT grid to cathode voltage at instrument turn on or off.
DS3 limits the CRT heater to cathode voltage.
This is an inverting amplifier with negative feedback. R22 is the feedback
resistor while R7, R20, and R33 act to maintain the summing junction at +5 V.
Without any Z-Axis input current, the amplifier output is approxi10 V.
Negative Z-Axis input current will cause the output to go positive.
Q5 is a current amplifier feeding the output stage. Q3 and Q4 form a push-pull
output stage. Q3 acts as a 2.7 mA constant current pull-up, while Q4 is the
pull-down transistor. C6 speeds up the amplifier by coupling ac signals to the
base of Q3. CR2 and R41 protect the amplifier during CRT arcing.
Focus Amplifier
Grid Drive Circuit
Z-Axis Amplifier
Содержание 1730 Series
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Страница 12: ...Contents viii...
Страница 17: ...Introduction and Specifications...
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Страница 32: ...1730 Series Introduction 1 14...
Страница 33: ...Operating Instructions...
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Страница 62: ...1730 Series Operating Instructions 2 28...
Страница 64: ...Service Safety Summary S 2 1730 Series B070000 Above...
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Страница 67: ...Installation...
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Страница 82: ...1730 Series Installation 3 14...
Страница 83: ...Theory of Operation...
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Страница 115: ...Checks and Adjustments...
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Страница 159: ...Maintenance...
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Страница 180: ...1730 Series Maintenance 6 20 3 Remove the board by slipping it through the front panel opening...
Страница 184: ...1730 Series Maintenance 6 24 Figure 6 8 Repackaging a 1730 Series instrument...
Страница 185: ...Options...
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Страница 189: ...Replaceable Electrical Parts...
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Страница 222: ...1730 Series Replaceable Electrical Parts 8 32...
Страница 223: ...Diagrams Circuit Board Illustrations...
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Страница 247: ...Replaceable Mechanical Parts...
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Страница 255: ...1730 Series Waveform Monitor FIG 1 EXPLODED VIEW A1 A3 A2 A3A1 A10 A11...
Страница 256: ...1730 Series B070000 Up...
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