3.4.4 - Front Panel Assembly
\)
The Front' Panel assembly is hinged to open upwards for
)
servlcmg. The faceplate silk-screening identifies each control. The
three circuit boards, Control Panel, Display and
Slider boards are
attached underneath. The Control Panel
bbard contains mostly
digital circuitry and the
Slider board contains mostly analog
ci rcu
itry.
The Display board consists of the liquid crystal display unit
(LCD)
and
its circuitry. The display shows numbers and text, letting
the user
carryon
a "dialogue" with the instrument. The
LCD
shows
two
lines of 24 characters each. Any letter, number or punctuation
can
be
shown.
The
display
is
used when a more elaborate message
is
needed than a flashing lamp
can
convey.
Control Panel Board
The Control Panel board
is
controlled and monitored by the
CPU
board. The signals from the CPU are decoded to see which
sub-system (switches, lamps, LCD, etc.)
is
to be activated.
The Control Panel board also contains
an
"analog-to-digital
converter" (ADC). This translates analog voltage levels into 8-bit
binary digital values.
The main functions of the Control Panel are:
1.
Control the LCD display
2. Control the LED's
3.
Control the switches
4. Convert AID
Kurzw,U
250
Service Manual, Chapter 3
3-
35
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