User`s guide

Maintenance 10
N1911A/1912A P-Series Power Meters User’s Guide 231
and measured internally. A pass or fail result is returned.
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 tested are the
LCD contrast control, the LED brightness control, and the display
temperature sensing diode.