Calibration Procedures 4
Keysight 34970A/34972A Service Guide 103
(Optional) 34902A Relay Contact Resistance Verification
This optional procedure uses an external DMM to make 4-wire ohms
measurements across the relay contacts on the 34902A. The measured resistance
is the series resistance of the two relay contacts (both contacts are in the same
relay).
Tests 1 - 4:
See the diagram on page 104 for the required connections for each test (be sure
to probe the components at the indicated location). For these measurements, the
34902A is not installed in the 34970A/34972A. Record the 4-wire ohms
measurements from the external DMM in the table below.
Be sure to read “Plug-in Module Test Considerations” on page 94.
The connections to the external DMM are different for each of Tests 1, 2, and 3.
Be sure to verify the connections shown in the table below for each of the three
tests.
Test #
External DMM Ohmmeter Connections
Measured Value
HI LO HI Sense LO Sense
1 L300 J101, C12 L300 J101, C12 _____________ Ohms
2 L301 J101, C14 L301 J101, C14 _____________ Ohms
3 L302 J101, C15 L302 J101, C15 _____________ Ohms
4 Add (Test 2 + Test 3) _____________ Ohms
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