Tektronix 1710J Series, Instruction Manual

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Theory of Operation
5–2
1710J-Series Waveform Monitors
The low voltage power supply is a high-efficiency switching type. the high
voltage power supply provides 13 kV acceleration potential.
Block Diagram
The Block Diagram for the 1710J-Series Waveform Monitor is located on a
foldout in Diagrams/Circuit Board Illustration section of this manual. The
following functional description uses the diagram as its illustration. The numbers
on the circuit blocks correspond to the schematic diagram where that circuit
block is detailed.
Color-encoded video signals are input through the bridging channel A and
channel B inputs. The input amplifiers are shunted by sample-and-hold-type
clamps, that are timed by a back porch sample from the back porch generator.
Switching at the output of the amplifiers provides for display of either input
signal or a combination of both in all sweep modes. In the combination mode,
the channel A signal is displayed on the left of the CRT with the channel B
following.
Front-panel switching can select a flat (unfiltered), a low pass, or a chroma
filtered signal for display. Low pass filtering can be used with flat as part of the
dual filter mode. In dual filter mode, the low pass filtered signal is displayed to
the left with the unfiltered (flat) signal following. When the calibrator signal is
selected (from the front-panel switching), a 1 volt, 100 kHz signal is applied to
the input of the gain cell instead of input video. The calibrator signal is used to
set up both vertical gain (volts full scale) and to check horizontal accuracy from
a common, self-contained source.
Signal amplitude can be adjusted at the gain cell using the front-panel V GAIN
control. The output signal from the gain cell drives another clamped amplifier.
This second clamped amplifier has a loop-compensated sample-and-hold circuit
to provide the fast clamping required for the fast dc restorer.
The vertical positioning voltage, along with the conditioned video signal, is
input to a switchable gain amplifier. Both amplifier gain and positioning range
can be increased by a factor of 5 when X5 Gain is selected at the front panel. The
limiter stage that follows prevents overdriving of the output amplifier.
The conditioned video signal and the Y component of the readout (from the
microcontroller) are input to the vertical output amplifier to match impedances
and normalize gain (approximately 40 V for 8 cm of vertical deflection) in order
to voltage drive the CRT vertical deflection plates.
Composite video from either internal (Channel A or B) or external reference has
all active video stripped away by the sync stripper to leave only sync to output a
sweep trigger.
Vertical
Horizontal