Maintenance
Diagnostic Testing
4
4-7
4-9. Diagnostic Testing
5520A internal software provides extensive self-testing capabilities. In case of a
malfunction, this is an excellent place to begin testing to isolate a faulty module.
Note
Self-tests should only be run after the 5520A has completed its warm-up.
Access the diagnostics menu as follows:
Press S followed by UTILITY FUNCTNS, and SELF TEST. The menu presents the
following choices:
• DIAG -- Runs internal diagnostics.
• FRONT PANEL -- Allows you to test the front panel knob, keys, bell, and displays.
• SERIAL IF TEST -- Does a loopback test between the two serial ports. For this test,
you attach a straight-through serial cable between the two serial ports. At least pins 2,
3, and 5 need to be connected.
• DIGITAL TEST -- Checks the RAM and bus on the Main CPU (A9).
4-10. Running Diagnostics
Press S followed by UTILITY FUNCTNS, SELF TEST, and DIAG. The menu
presents the following choices: OPTIONS and GO ON. Press GO ON to start diagnostics.
The 5520A prompts you to remove all cables from the front panel outputs. Install a low-
ohm copper short circuit across the 20 A and Aux Lo terminals.
After you press the GO NO softkey, an automatic sequence of tests begins. Diagnostics
runs a set of steps similar to zero calibration and reports similar errors.
4-11. Testing the Front Panel
Press S followed by UTILITY FUNCTNS, SELF TEST, and FRONT PANEL. The
menu presents the following choices: KNOB TEST, KEY TEST BELL TEST, and
DISPLAY. These tests are described next:
• KNOB TEST -- Tests the knob encoder by showing a cursor that moves when you
turn the knob.
• KEY TEST -- Lets you check the proper functioning of each key. When you press a
key, the name of the key shows on the display. Press PREV MENU to exit this test.
• BELL TEST -- Lets you ring the bell (beeper) for various timed periods.
• DISPLAY -- Checks all the segments of the two displays.
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