16
Connections
Connections are made to the front panel terminals using a 4-wire configuration as described in
4-
Wire Resistance Measurement
. When using Valhalla test leads, the tabbed side of the banana
jack is plugged into the current terminals. This ensures that the current is carried in the largest
conductor and that the voltage input is shielded.
V
HI
☼
☼
I
HI
←
Tab
V
LO
☼
☼
I
LO
←
Tab
Interpreting the Display
All Valhalla ohmmeters use a high impedance voltmeter as part of the resistance measurement
process. This voltmeter is a highly accurate and stable 4 ½ digit analog-to-digital converter (A to
D). Unless it is receiving a definite input signal, the output reading of this A to D is ambiguous.
The display may indicate a randomly wandering number or it may indicate an overrange
condition. This unpredictable display may make it seem to appear that the instrument is
experiencing some sort of malfunction. It is, in fact, just a characteristic of the voltmeter circuit
and should not be mistaken for a fault in the instrument.
The display indications should be ignored unless there is a definite measurement being taken. If
this wandering display is not acceptable, the ohmmeter can be made to indicate an overrange
condition whenever the terminals are open by using a 4-wire Kelvin type lead set or by shorting
the VHI and IHI terminals together.
The display should indicate a stable reading when the test leads are securely attached to the
device under test. If the display appears to be erroneous when connected to a load, recheck the
test leads for integrity and cleanliness. If all external items appear to be functioning properly, the
problem may be the ohmmeter. In this case, please contact your local Valhalla Scientific Sales
Office.
