Incorrect Low Frequency Response (Pulse Flatness); Incorrect Input Resistance; Incorrect Offset; Offset Will Not Zero - Agilent Technologies 1156A User Manual

Service
Failure Symptoms

Incorrect Low Frequency Response (pulse flatness)

If the probe's pulse response shows a top that is not flat (incorrect ac gain), it is
most likely caused by an inaccurate 50 Ω load on the probe. The probe is
designed to work into a 50 Ω load that is accurate within 1.0% (±0.5 Ω). Check
the value of the load you are using before you suspect the probe. If the load is
accurate, the gain problem with the probe will have to be repaired by the factory.
If the probe appears ac coupled at a high frequency, check for a loose or damaged
probe tip.

Incorrect Input Resistance

First, check that the probe tip is not loose. The input resistance is determined
in the amplifier hybrid in the probe and cannot be repaired in the field. The
probe must be returned to the factory for repair.

Incorrect Offset

Incorrect offset can be caused by a misadjusted offset zero (see "Offset Will Not
Zero" below) or lack of probe calibration with the oscilloscope.

Offset Will Not Zero

With the input voltage set to 0.0 V and no offset setting, the dc output of the
probe should be within ±3 mV.
If the probe is connected to an Infiniium oscilloscope, the oscilloscope will
calibrate out the offset zero error during a probe calibration. If the offset error
cannot be calibrated out, return it to Agilent Technologies for repair.
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