Keysight E4990A Troubleshooting Manual page 4

Caution
Impedance Analyzer
Do not exceed the operating input power, voltage, and
current level and signal type appropriate for the instrument
being used, refer to your instrument's Function Reference.
Electrostatic discharge (ESD) can damage the highly
sensitive microcircuits in your instrument. ESD damage is
most likely to occur as the test fixtures are being connected or
disconnected. Protect them from ESD damage by wearing a
grounding strap that provides a high resistance path to ground.
Alternatively, ground yourself to discharge any static charge
built-up by touching the outer shell of any grounded instrument
chassis before touching the test port connectors.
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