General Adjustment Considerations - Keithley DMM6500 Manual

Section 3: Adjustment

General adjustment considerations

•
DMM6500 dc voltage performance is sensitive to errors from thermoelectric potentials generated
by test cables and connections. Be sure to use high-quality cables and connection techniques.
When changing a connection during the adjustment process, be sure to allow time (up to five
minutes) for thermal settling. Also allow thermal settling time, typically 60 seconds, when
changing the TERMINALS FRONT/REAR switch position during adjustment.
•
Calibration steps are performed on both rear and front inputs as described in sections below. Be
sure that the TERMINALS FRONT/REAR switch is in the proper position before sending
adjustment commands.
•
The Keithley Models 8610 and 8620 4-wire shorts connect all four terminals electrically, but the
layout of the board traces makes DMM6500 adjustment sensitive to their orientation. Note the
HI/LO terminal markings and be sure to insert connections in the correct orientation. Note that the
DMM6500 rear input terminals are rotated 90° compared to front-panel inputs.
•
During adjustment steps using a calibrator reference source, be sure the calibrator reference
signal has fully settled before sending adjustment commands to the DMM6500.
The front and rear terminals of the instrument are rated for connection to circuits rated
Measurement Category II up to 300 V, as described in International Electrotechnical
Commission (IEC) Standard IEC 60664. This range must not be exceeded. Do not connect the
instrument terminals to CAT III or CAT IV circuits. Connection of the instrument terminals to
circuits higher than CAT II can cause damage to the equipment and severe personal injury.
The maximum input voltage between INPUT HI and INPUT LO is 1000 VDC and 750 VAC.
Exceeding this value may create a shock hazard.
The maximum common-mode voltage (the voltage between INPUT LO and chassis ground) is
500 V . Exceeding this value may cause a breakdown in insulation that can create a shock
PEAK
hazard.
The information in this section is intended for qualified service personnel only, as described
by the types of product users in the Safety precautions pages, provided at the beginning of
this document. Do not attempt these procedures unless you are qualified to do so.
Some of these procedures may expose you to hazardous voltages, that if contacted, could
cause personal injury or death. Use appropriate safety precautions when working with
hazardous voltages.
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DMM6500 6½-Digit Multimeter with Scanning Calibration and Adjustment Manual
DMM6500-905-01 Rev. E June 2021