31
SOURCE ADJUSTMENTS
1.
Select 200Ω
range.
2.
Connect to a 100Ω standard resistor.
Adjust RV10 for a display reading equal to the value of the resistor.
3.
Select 2kΩ range and connect to a 1kΩ standard resistor.
Adjust RV11 for a display reading equal to the resistor value.
4.
Select 20kΩ range and connect to a 10kΩ standard resistor.
Adjust RV12 for a display reading equal to the resistor value.
5.
Select 200kΩ range and connect to a 100kΩ standard resistor.
Adjust RV13 for a display reading equal to the resistor value.
6.
Select 2MΩ range and connect to a 1MΩ standard resistor.
No adjust. Verify that display reading is within tolerance of the resistor value.
7.
Select 20MΩ range and connect to a 10MΩ standard resistor.
No adjust. Verify that display reading is within tolerance of the resistor value.
8.
Select 2Ω range and connect to a 1Ω standard resistor.
No adjust. Verify that display reading is within tolerance of the resistor value.
9.
If the 2Ω range is too low, select R27 using a Resistance Decade Box.
10.
Select 20Ω range and connect to a 10Ω standard resistor.
No adjust. Verify that display reading is within tolerance of the resistor value.
11.
If the 20Ω range is too low, select R37 using a Resistance Decade Box.
IMPORTANT:
If it is necessary to perform step 9 or 11, go back and forth between the 2Ω, 20Ω and 200Ω
ranges until all are in spec.
FAILSAFE CHECK
1.
Connect the 3458A in the ammeter mode across the current terminals. Select the 2Ω range.
2.
Short J10 and verify that the measured current is equal or less then the value specified in the Fail-
Safe current table.
3.
Repeat this process for each range.
4.
For MΩ ranges it will be necessary to connect the appropriate calibration resistor and measure
the voltage drop across it. Use Ohm’s Law to calculate the failsafe current.
Range
Fail-Safe Current
2Ω
8mA
20Ω
8mA
200Ω
1.8mA
2kΩ
180µA
20kΩ
18µA
200kΩ
1.8µA
2MΩ
180nA
20MΩ
18nA
