Tektronix 2230 Service Manual

Operating Information—2230 Service
components at or near the circuit’s resonant frequency.
Oscillations (ringing) can then appear on the oscilloscope
waveform display and distort the true signal waveshape.
Always Keep both the ground lead and the probe signal-
input connections as short as possible to maintain the
best waveform fidelity.
Misadjustment of probe compensation is a common
source of measurement error. Due to variations in oscillo
scope input characteristics, probe compensation should be
checked and adjusted, if necessary, whenever the probe is
moved from one oscilloscope to another or between chan
nels. See the probe compensation procedure in
•Operator’s Check and Adjustments', or consult the
instructions supplied with the probe.
Coaxial Cables
Cables may also be used to connect signals to the ver
tical input connectors, but they may have considerable
effect on the accuracy of a displayed waveform. To main
tain the original frequency characteristics of an applied sig
nal, only high-quality, low-loss coaxial cables should be
used. Coaxial cables should be terminated at both ends in
their characteristic impedance. If this is not possible, use
suitable impedance-matching devices.
INPUT-COUPLING
CAPACITOR PRECHARGING
When the Input Coupling switch is set to the GND posi
tion, the input signal is connected to ground through the
input-coupling capacitor and a high resistance value. This
series combination forms a precharging circuit that allows
the input-coupling capacitor to charge to the average dc
voltage level of the signal applied to the input connector.
Thus, any large voltage transients that may accidentally be
generated are not applied to the vertical amplifier’s input
when the input coupling is switched from GND to AC. The
precharging network also provides a measure of protection
to the external circuitry by reducing the current level that
is drawn from the external circuitry while the input
coupling capacitor is charging.
If AC input coupling is in use, the following procedure
should be followed whenever the probe tip is connected to
a signal source having a different dc level than that previ
ously applied. This procedure becomes especially useful if
the dc-level difference is more than ten times the
VOLTS/DIV switch setting.
1. Set the AC-GND-DC (input coupling) switch to GND
before connecting the probe tip to a signal source.
2. Touch the probe tip to the oscilloscope GND con
nector.
3. Wait several seconds for the input-coupling capaci
tor to discharge.
4. Connect the probe tip to the signal source.
5. Wait several seconds for the input-coupling capaci
tor to charge to the dc level of the signal source.
6. Set the AC-GND-DC switch to AC. A signal with a
large dc component can now be vertically positioned within
the graticule area, and the ac component of the signal can
be measured in the normal manner.
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Tektronix 2230 Specifications

General

Brand	Tektronix
Model	2230
Category	Test Equipment
Language	English