Tektronix TDS1000B Series Operator's Manual page 169

6. Push the appropriate side-screen menu button to select
Coupling DC.
7. Turn the CH1 POSITION knob counterclockwise to set
the vertical position at 0.00 divs (0.00V).
Notice that the flatness of the probe compensation
waveform changes when you switch from AC coupling
to DC coupling. This happens because AC coupling is a
high pass filter that blocks a component of the signal.
8. Turn the CH1 POSITION knob counterclockwise to set
the vertical position at -100.00 divs (-5.00V).
Recalibrate the probe for a square waveform.
TDS1000B and TDS2000B Series Oscilloscopes – Operator Training Kit
Using VERTICAL Controls
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