Keysight Technologies L4490A, Руководство пользователя

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Keysight L4490A/L4491A User’s Guide 9
L4490A/91A Service Information
6 L4490A/91A Service Information
System Diagnostics
A common problem is getting verification failures upon reset or power up due to
the (improper) configuration of the default states. An example would be setting
the default state of an 87106 to more than one position, or one position and the
open all position.
Often the most common problems with switches/attenuators connected to the
internal 34945EXT di
s
tribution module through plug-in distribution boards are
related to the switch and attenuator cables. A seventh distribution board, the
Y1156A Plug-in Test & Diagnostic distribution board, is used to provide visual
confirmation of the signal path from the PC to distribution board banks 1-4.
Verifying the path from the PC to a selected bank helps isolate suspected
problems in the entire path from PC to switch. Many Keysight switches contain
position indicator options that allow for electronic verification of the switch
position. The 34945EXT contains circuitry to detect these signals, and the
Y1156A diagnostic board can also be used to test the functioning of this circuitry.
Performance Verification Tests
Use the Performance verification tests to verify the operation performance of the
L4490A/91A switchbox mainframe power supply and control module. The
installed switches and attenuators must be tested separately. See the separate
documentation for those devices.
You can perform two different levels of performance verification tests:
- Self-Test - A series of internal verification tests that give a high confidence that
the instrument is operational.
- Complete Selt-Test - An extensive set of tests that are recommended as an
acceptance test when you first receive the instrument.
The repair strategy is module replacement. You can replace the power supply
module and/or the built-in 34945EXT distribution module. Contact the factory if
you need to replace the complete controller/power supply module.
Recommend Service Tool is Y1156A Test & Diagnostic Fixture.