Tektronix 2235A Instruction Manual page 50

'Theory of Operation
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2235A
Instruction
In the X-Y mode of operation, the Channel 1 signal from
the Internal Trigger circuitry passes through the X-Y
Amplifier to the Horizontal Preamplifier. In this operating
mode, the Channel 1 Internal Trigger signal supplies the
horizontal deflection to the crt, and the Miller Sweep
circuit is disabled to inhibit sweep generation.
The Alternate
B
Sweep circuitry controls the Alt and B
Horizontal mode displays and includes the
B
Miller
Sweep- Generator and B Sweep Logic circuitry. In
addition to providing the
B
Sweep sawtooth waveform,
signals are generated which control the display
switching between the A and B displays.
The intensity levels of both the A and
B
Sweeps are set
by the front-panel A and
B
INTENSITY controls. These
controls, along with signals from the A and
B
Sweep
Logic circuits, determine the drive level to the Z-Axis
Amplifier.
The Z-Axis drive from both the A Sweep Logic circuit and
the Alternate B Sweep circuit is applied to the Z-Axis
Amplifier. The output signal from the Z-Axis Amplifier
circuit sets the crt intensity. When using Chop Vertical
mode, a blanking signal from the Chop Oscillator circuit
blanks the crt display while switching between the
vertical channels.
The Dc Restorer circuit applies the output voltage of the
Z-Axis Amplifier between the cathode and grid of thecrt.
High dc potentials on these elements prohibit direct
coupling to the crt.
The Power Supply provides the necessary operating
voltages for the instrument. Operating potentials are
obtained from a circuit composed of the Preregulator,
Inverter and Transformer, and Rectifiers and Filters. The
Preregulator produces approximately
+
43 V dc from the
ac power line which is used to drive the 20 kHz Inverter
stage. The transformer secondary windings provide
various ac levels that are rectified and filtered to produce
the operating voltages. A high voltage multiplier circuit
produces the accelerating, focus, and cathode
potentials required by the crt.
A front-panel CAL output is provided for use in adjusting
probe compensation and for checking vertical deflection
accuracy. The voltage at the CAL connector is a
negative-going square wave that has a peak-to-peak
amplitude of 0.5 V and a repetition rate of 1 kHz.
Scans by ARTEK MEDL4
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