4 Calibration Procedures
96 Keysight 34970A/34972A Service Guide
(Optional) 34901A Relay Contact Resistance Verification
This optional procedure uses an external DMM to make 4-wire ohms
measurements across the relay contacts on the 34901A. The measured resistance
is the series resistance of the two relay contacts (both contacts are in the same
relay).
Tests 1 - 5:
See the diagram on page 97 for the required connections for each test (be sure to
probe the components at the indicated location). For these measurements, the
34901A 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, 4, and
5. Be sure to verify the connections shown in the table below for each of the four
tests.
Test #
External DMM Ohmmeter Connections
Measured Value
HI LO HI Sense LO Sense
1 L401 J101, C14 L401 J101, C14 _____________ Ohms
2 L402 J101, C15 L402 J101, C15 _____________ Ohms
3 Add (Test 1 + Test 2) _____________ Ohms
4 F501 C21 I F501 C21 I _____________ Ohms
5 F502 C22 I F502 C22 I _____________ Ohms
Connect bare copper wires (approximately 3 cm in length) to the I terminals of
Channels 21 and 22 as shown below. These wires will be used to make shorts
across the channels in Tests 6 through 39.
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