Teledyne LeCroy AP033 - Manual (Page 21)

Operator’s Manual
922260-00 Rev A 15
Figure 4, Effect of Differential Offset
When the AP033 is used with a Teledyne LeCroy oscilloscope equipped with a ProBus interface and
software versions 7.6.0 to 8.0.0, the probe offset must be controlled through either the Probe
Offset menu selection in the COUPLING screen, or the buttons on the probe body. The channel
O
FFSET
control does not change the probe offset and, therefore, should not be used.
When used with the ADPPS Power Supply on instruments that lack ProBus support, offset can be
controlled with the buttons on the front panel. The offset can be returned to zero at any time by
briefly pressing the ↑ and ↓ O
FFSET
buttons at the same time. Pressing and holding the ↑ and
↓ O
FFSET
buttons for more than two seconds will initiate an Autobalance cycle.
Autobalance
The AP033 incorporates an Autobalance function to remove the DC offset from the output.
Autobalance must be invoked by you. When power is first applied, the probe will return to the
internal values resulting from the last Autobalance cycle. For Autobalance to function properly, all
signals must be removed from the input.
After several minutes of warm up, or when the probe is exposed to a large shift in ambient
temperature, some DC offset drift may occur from thermal effects in the amplifier circuitry. To
initiate an Autobalance cycle, remove the probe from the test circuit and select AUTOBALANCE
from the oscilloscope’s COUPLING menu for the channel the probe is connected to. If the probe is
being used with the ADPPS power supply, remove the input signal, and push and hold both the
OFFSET buttons for two seconds. The AP033 output must be terminated into 50 Ω for successful
Autobalance.