Agilent Technologies E4418B User Manual page 112

Power Meter Operation
Self Test
• RS232/RS422 Loop Back - A message is sent via the UART and
transceivers using an external loop back connector (refer to the Agilent
E4418B/E4419B Service Guide).
Option 001 Battery
This test checks that the capacity of the option 001 battery has not decayed below 70
% of its original value. The test is only performed on power meters fitted with option
001.
Calibrator
The reference calibrator is turned on (indicated by the POWER REF LED) and
measured internally. A pass or fail result is returned.
Keyboard (Front Panel only)
The power meter enters a mode where you are invited to press any key. When a key is
pressed, its name appears on the screen. You can check that the power meter is
displaying the expected name when the relevant key is pressed. This is a check that
the power meter is receiving the correct keyboard signal. Pressing the same key twice
sequentially exits this mode and returns you to a display that lists all the keys that
were not entered. If the test is exited without all the keys being pressed a list is
displayed showing all the keys which were not selected.
Display
Three tests are available for the display: the display assembly, display RAM and
bitmap display.
A read/write is performed on the display RAM. If the value which is written is read
back correctly, a pass is recorded, otherwise a fail is recorded.
The liquid crystal display/ light emitting diode (LCD/LED) control circuits are tested
by making separate voltage measurements via the multiplexer and digital signal
processor. If the expected voltages are measured, a pass is recorded, otherwise a fail is
recorded. The three circuits which are tested are the LCD contrast control, the LED
brightness control and the display temperature sensing diode.
Bitmap Display (Front Panel only)
A series of bitmaps are displayed on the power meter showing: two checkboards,
vertical lines, horizontal lines, oblique lines, all pixels on and all pixels off. Pressing
cycles you through these bitmaps. The
More
returns you to the previous menu.
2-70
key stops the display and
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Agilent E4418B User's Guide