Service manual

8508A
Service Manual
3-38
Procedure
Perform the following sequence for each resistance mode and each range, as listed in
Table 3-10, starting with the 2 Ω range and working up to the 2 GΩ range for the
NormalΩ and NormalΩ LoI resistance modes. Then continue the sequence for the TruΩ
and TruΩ LoI modes, starting with the 2 Ω range and working up to the 20 kΩ range.
Finally complete the sequence for the HiVΩ mode, starting with the 20 MΩ range and
working up to the 20 GΩ range. An input zero operation is performed on each Multimeter
range prior to performing the range verification measurements with the calibrator set to
zero Ω. A separate zero operation is required on each range for each resistance mode.
Note that EX SNS (4-wire) is not available on the 5720A 100 MΩ range, and the 8508-
7000K 1 GΩ standard resistor is used as a 2-wire device with the calibrator 2-wire
resistance zero used for the corresponding zero point.
4WΩ is deselected on the
Multimeter when checking the 200 MΩ and 2 GΩ range, range zero, and range gain
points.
XW Warning
The Multimeter can deliver a lethal electric shock when
operating in the High Voltage Resistance mode. Voltages up to
240V may appear on the terminals.
To avoid electric shock when performing the following
calibration procedures:
• Never touch any lead or terminal unless you are absolutely
certain that no dangerous voltage is present.
• Make sure that signal leads are in a safe condition before you
handle them in any way.
1. Press the
Ω key.
2. Press the
CONFIG key and select Filt, RESL7, and 4wΩ. Ensure LoI is deselected.
3. Select the required Multimeter range.
4. On the Calibrator, select zero Ω and Operate. Alternatively if using a standard
resistor connect the standard resistor for a 4-wire resistance zero. (For the 200 MΩ
range and above, de-select Ex SNS on the calibrator and de-select
4WΩ οn the
Multimeter.)
5. On the Multimeter press the
INPUT key, and select Zero Rng to initiate the zeroing
operation.
The
Busy legend will appear, and then extinguish when the zero operation has
completed.
6. On the Calibrator, select Range Gain point Output value. Alternatively if using a
standard resistor re-connect the standard resistor to measure its resistance.
7. Note the Multimeter’s reading. Compare the result with the allowable tolerance,
taking into account the actual value of the calibrator resistance output for this value
or the calibrated value of the resistance standard used.
8. Repeat steps 3 – 7 for the remaining ranges of the selected resistance mode. (For the
2 GΩ and 20 GΩ ranges the 8508-7000K 1 GΩ standard resistor is used in place of
the calibrator. For the 200 MΩ range and above, de-select Ex SNS on the calibrator
and de-select
4WΩ οn the Multimeter).
9. Set the calibrator output to
STANDBY.
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