7: Low Ohms, Adjusting Low Ohms Source; 8: Hi Ohms, Adjusting High Resistance Measure - Fluke 525A Service Manual

525A
Service Manual

7: Low Ohms, Adjusting Low Ohms Source

When calibrating the 5-400 Ω output range (High Ohms Source), the calibrator outputs
two calibration points. After the output becomes stable, the values are entered at the PC.
1. Use the same test equipment listed in Table 16.
2. Use the same connections as in 6: Adjusting High Resistance Source.
3. Set the DMM to measure 4-wire ohms.
4. Type 7, then press the Enter key on the PC. The PC will display:
5. When the reading displayed on the DMM stabilizes, type the reading value on the PC
6. When the reading displayed on the DMM stabilizes, type the reading value on the PC

8: Hi Ohms, Adjusting High Resistance Measure

When adjusting the calibration for the 5-4000 Ohms Measure range (High Ohms
Measure), the Calibrator will first measure a short and then two resistances. Refer to
Table 19 for a list of equipment used in this section.
Manufacturer
Fluke
Fluke
Fluke
Wavetek
1. Insert a 4-wire short into the 525A 4W RTD Ω jacks.
2. Type 8 then press the Enter key on the PC. The following will show on the PC:
Input 0 Ohms, Press Enter When Stable
3. Allow a few seconds for stabilization, then press the Enter key. In a few moments the
following appears on the PC:
Input ~2000 Ohms, Enter the actual value when stable:
The ~2000 indicates that the desired resistance is about 2000 Ω. The actual resistance is
not as important as the accuracy with which the value is known. The method described
below uses the 1281 to establish a ratio between the 5520A output and the 742 to
improve the accuracy with which the 5520A's output resistance is known.
38
First Calibration Point. Enter the Ohms displayed:
and press the Enter key. After the value has been entered, the PC displays the
following:
Second Calibration Point. Enter the Ohms displayed:
and press the Enter key. After the second value has been entered, the Calibrator will
return to the calibration menu.
Table 19. List of Equipment for High Ohms Measure Calibration Adjustments
FLUKE-525A/LEADS
742A-10K
5520A
1281
Model
Test Lead Set
Resistance Standard, 10K Ω
Calibrator
DMM
Equipment