Assembly Level Troubleshooting 4
Keysight 3458A Assembly-Level Repair Manual 123
RAM failures
These failures show up when the checksum of either the RAM or the Calibration
RAM is incorrect. If a failure occurs, a message indicating that the checksum is
incorrect will be displayed. Since both RAMs are located on the Outguard
Controller (A5) assembly, replace that assembly for any RAM failure. Use the
Assemblies Removal/Installation Procedures in Chapter 3 of this manual to
replace the assembly.
Self-test failures
General
The 3458A self-tests perform very extensive tests on the instrument circuitry so
that most hardware or calibration self-test failures will be detected by these tests.
Self-test failures can show up either during the power-on self-test or during the
front panel selectable self-test. The power-on self-test is automatically performed
after the instrument is turned on. The complete self-test must be selected from
the front panel. To select this test, press the blue “SHIFT” key and then the 'Test”
(left arrow) key.
Self-test failure indication
The power-on and selectable self-tests use two different ways to indicate failures.
With the power-on test, the “ERR” annunciator in the display normally turns on to
indicate that a test has failed. In addition to the “ERR” annunciator, the message
'SELF TEST FAILED' will also be displayed.
Self-test error messages
Any time the 3458A detects a self-test failure; a corresponding error message is
stored into the auxiliary error registers. To determine what failed, this error
message must be retrieved from the registers and displayed. To display the
message, press the blue “SHIFT” key and then the “Error” key (on the NUMERIC/
USER keyboard). Once the message is displayed, it is then erased from the
registers. Because of this, make sure you note the complete message before
continuing. Use the right arrow key to view the complete message.
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