Keithley SourceMeter 3A 2420, Service Manual

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1-2 Performance Verification
Introduction
Use the procedures in this section to verify that Model 2420 accuracy is within the limits stated
in the instrument’s one-year accuracy specifications. You can perform these verification procedures:
• When you first receive the instrument to make sure that it was not damaged during shipment.
• To verify that the unit meets factory specifications.
• To determine if calibration is required.
• Following calibration to make sure it was performed properly.
WARNING The information in this section is intended for qualified service personnel
only. Do not attempt these procedures unless you are qualified to do so.
Some of these procedures may expose you to hazardous voltages, which
could cause personal injury or death if contacted. Use standard safety pre-
cautions when working with hazardous voltages.
NOTE If the instrument is still under warranty and its performance is outside specified limits, con-
tact your Keithley representative or the factory to determine the correct course of action.
Verification test requirements
Be sure that you perform the verification tests:
• Under the proper environmental conditions.
• After the specified warm-up period.
• Using the correct line voltage.
• Using the proper test equipment.
• Using the specified output signals and reading limits.
Environmental conditions
Conduct your performance verification procedures in a test environment with:
• An ambient temperature of 18-28°C (65-82°F).
• A relative humidity of less than 70% unless otherwise noted.
Warm-up period
Allow the Model 2420 to warm up for at least one hour before conducting the verification
procedures.
If the instrument has been subjected to temperature extremes (those outside the ranges stated
above), allow additional time for the instrument’s internal temperature to stabilize. Typically, al-
low one extra hour to stabilize a unit that is 10°C (18°F) outside the specified temperature range.
Also, allow the test equipment to warm up for the minimum time specified by the manufacturer.