Self-Test Procedures; Power-On Self-Test; Complete Self-Test; Performing Individual Tests - Keysight Technologies 34420A Service Manual

Self-Test Procedures

Power-On Self-Test

Each time the meter is powered on, a small set of self-tests are performed. These
tests check that the minimum set of logic and measurement hardware are
functioning properly. The power-on self-test performs checks 601, 625, and 626.

Complete Self-Test

Hold the shift key for 5 seconds while turning on the power to perform a complete
self-test. The meter beeps when the test starts. The tests are performed in the
order shown below.

Performing Individual Tests

You can perform individual self-tests through the SYStem menu and TEST
command. At the parameter level, you can choose to TEST ALL or scroll through a
list of test numbers. All numbered tests are looped to give a continuous pass/fail
indication when started from the menu (they will repeat the test until interrupted).
601 Front panel does not respond The main CPU U500 attempts to establish serial
communications with the front panel processor U602. During this test, U602 turns on all
display segments. Communication must function in both directions for this test to pass. If
this error is detected during power-up self-test, the meter will beep twice. This error is only
readable from the remote interface.
602
RAM read/write failed This test writes and reads a 55h and checkerboard pattern to each
address of ram U503. Any incorrect readback will cause a test failure.
603 A/D sync stuck The main CPU issues an A/ D sync pulse to U500 and U501 to latch the
value in the ADC slope counters. A failure is detected when a sync interrupt is not
recognized and a subsequent time-out occurs.
604 A/D slope convergence failed The input amplifier is configured to the measure zero (MZ)
state in the 10 V range. This test checks whether the ADC integrator produces nominally
the same number of positive and negative slope decisions (±10%) during a 20 ms interval.
605 Cannot calibrate rundown gain This test checks the nominal gain between the integrating
ADC and the U500 on-chip ADC. This error is reported if the procedure can not run to
completion due to a hardware failure.
606
Rundown gain out of range This test checks the nominal gain between the integrating ADC
and the U500 on-chip ADC. The nominal gain is check to ±10% tolerance.
Keysight 34420A Service Guide
Service 5
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