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CONTROLS AND CONNECTORS
A ll controls and connectors necessary for operation of
the 221
are located on the right side panel of the
instrument. See Fig. 2-1. A brief description of each control
and connector is given here.
V O LT S /D IV — selects vertical deflection factor (VAR
VO LTS/DIV must be in the CAL position for indicated
deflection).
STEP ATTEN B A L— screwdriver adjustment to balance
the vertical system for minimum trace shift when changing
deflection factors.
Vertical POS— controls the vertical position of the trace.
VERT G A IN — screwdriver adjustment to set the gain of
the vertical system.
VAR
V O LT S /D IV —provides a continuously variable
deflection factor between the calibrated settings of the
VOLTS/DIV switch.
INPUT COUPLING— selects method used to couple the
input signal to the vertical amplifier system.
REV. B, FEB. 1977
FUNCTIONS OF
frequency lim it (—3 dB point) is about two hertz.
connected to ground through a large resistor to provide a
precharge path for the AC input coupling capacitor.
vertical amplifier system.
in the CAL detent; HORIZ MAG must be in X I position,
for indicated sweep rate). 1 V position allows fo r X-Y
operation w ith the horizontal deflection provided by the
signal connected to the EXT TRIG OR HORIZ INPUT
jack.
trace.
rates between calibrated settings of the SEC/DIV switch.
Extends
0.5 second/division.
sweep time to 0.1 microsecond/division and provides a
horizontal sensitivity of 0.1 volt/division in X-Y operation.
Fig. 2-1
Side panel showing controls and connectors.
AC—blocks dc components
GND—Input circuit is grounded. The applied signal is
DC— All components of the input signal are passed to the
SEC/DIV selects the sweep rate (VAR SEC/DIV must be
Horizontal POS— controls the horizontal position o f the
VAR SEC/DIV—provides continuously variable sweep
the
minimum
HORIZ MAG—X10 magnifier to increase the maximum
Section 2 —221 Service
of
input
signal.
Low
sweep
rate
to
about
2-1
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