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Chapter 9 Routine Maintenance
General
This Chapter provides general maintenance information and a procedure for calibrating the
ohmmeter. The Model 4100 Series ohmmeters should be calibrated on a routine basis (every 12
months is recommended) to ensure continued accuracy.
Before performing the calibration procedure below, the ohmmeter should be allowed to warm up at
a stable temperature for at least 30 minutes with the covers in place.
Required Test Equipment
The following equipment is required to perform calibration of the product:
1) Precision Resistors with known values to within ±0.005%, having the following values:
0.01Ω
[1]
, 0.1Ω
[1]
, 1.0Ω
[1]
, 10Ω
[1]
, 100Ω
[1][2]
, 1KΩ
[2]
and 10KΩ
[2]
[1] May be replaced by Valhalla Model 2575A.
[2] May be replaced by Valhalla Model 2724A.
2) DC Voltage source with available outputs of 0 to 200mV ±2µV (Valhalla Model 2701C)
3) Four-terminal test lead set (Valhalla Option "K" or Option "C")
4) For 4165 & 4165-1344 only:
a voltmeter capable of measuring 20mV within ±1mV, 50mV within ±5mV, and 2V within
±10mV.
Note: If this equipment is not available, the ohmmeter may be returned to Valhalla Scientific for
calibration traceable to NIST.
Pre-Calibration Procedure
The calibration adjustments are accessed by removing the top cover of the instrument. If the
ohmmeter has been fitted with any of the optional interfaces (IEEE, RS232C, or printer), the blue
interface PCB will cover the adjustments. This installation has been designed to facilitate
calibration by using hinged stand-offs to allow access to adjustments. To enable this board to tilt
upward, remove only the black screw in the rear corner of the interface PCB. Replace this screw
when finished with calibration.
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