Operating
Instructions—7A42
Figure
2-10.
7A42 front-panel drawing showing pushbuttons and Indicators
that are
Illuminated
during the
self-test sequence.
front-panel
pushbuttons and
all
of
the
indicators
are
momentarily
illuminated
to
verify
their
operation.
Figure
2-10
shows
which
ones
should
light.
The
SWITCHING
THESHOLD
VOLTS
indicator
will
display
8.8.8.8.
during
the
first
part
of
the
self-test
sequence
to
verify
that
all
segments
operate.
If
there
are
no
self
test
failures,
the
Firmware
Version
number
will
then
be
displayed
for a few
seconds
before
the self
test
is
completed.
Self-test
failures
are
indicated
by
three
different
methods:
1.
on
the
mainframe
crt,
2.
on
the
7A42
SWITCHING
THRESHOLD display,
and 3.
on
the
TRIGGER
FUNCTION
indicators.
Figure
2-11
illustrates
a
typical
self-test
failure,
indicated
by
the
three
display
methods.
Displaying
the self-test
failure messages in three
different
ways
increases
the
chance
that
the
failure
message will
be
displayed,
even
if
the
failure
affects
the
operation
of
two
of
the
three
display
methods.
The
TRIGGER
FUNCTION
display
indicates
a
self-test
failure
with
the
color
red
and
self-test
passed
with
the
color
green.
If
a
failure
occurs,
the
self-test
sequence
will
stop.
2-49
REV
JUL
1984