5.2 When the Device Appears to be a Problem
5-9 ZM2376
Table 5-1 When the device appears to be a problem 3/4
Measured value
differs largely
from the expected
value,
measurement is
impossible,
or
correction values
cannot be
measured
Wrong correction values are set.
Try to turn off OPEN, SHORT, and LOAD correction.
Check the frequency range for correction.
Re-measure or re-set correction values.
Measurement conditions are
incorrect.
Set the frequency and signal level to the specified
values. Measured value may vary largely with the
measurement conditions depending on the DUT.
Improper measurement range is
held.
Switch to a proper measurement range, or enable the
auto selection of measurement range.
The shield-to-shield connection
of connection cables is not
made.
For four connection cables, connect their outer
conductor (shields) together. Otherwise, a return path
of measurement current is not formed, causing a
measurement failure.
Connection cables to DUT or
contacts are defective.
Check the cables for continuity, or the inner and outer
conductors for short-circuit, or the contacts for
contamination.
If a contact failure of the L
CUR
terminal occurs, the
bridge may be unbalanced to cause an error display.
The L side of DUT is grounded.
Or, DUT is grounded with low
impedance.
Do not connect the DUT’s terminal to the ground. It
can be checked with a multimeter. ZM2376 cannot
measure the grounded DUT. This is also true for the
measurement of correction values.
Internal impedance bridge is
unstable (too large capacitance
between L terminal of DUT and
ground).
Including the capacitance of four connection cables,
reduce the capacitance between L terminal of DUT
and ground. Check the capacitance to ground
(capacitance to shield), which may be very large for a
large DUT or DUT having complex construction.
Noise mixes in. Exposed signal
lines (particularly L side) are
near to a portion where potential
variations are extreme.
When measuring high impedance such as OPEN
correction, electrostatic-shield the signal lines or
ensures adequate distance from noise sources.
Ground the case and peripheral conductors. When
the signal level is small or the frequency is high, the
device is likely to be interfered.
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