Fluke 93 Service Manual page 72

PERFORMANCE
VERIFICATION
PROCEDURE 4-3
^/
2
.
LCD
test
While
In
the
SERVICE
menu, press
the
SCOPE
softkey
to
enter the
SCOPE
section
of
the
Performance
Verification
Procedure.
Now
a
(dark) test pattern
is
displayed. This pattern consists
of
a
circle
placed
In
a
square,
and
a diagonal
line
(see
figure
4.2).
Observe
the
test pattern closely.
The
lines
may
not
be
Interrupted;
the pattern
must be
continuous.
In this test
sets the c^splay to
a
high contrast, resulting
In
a dark
display.
If
there
are
defects
In
the
pixel
columns
of
the
Liquid Crystal Display, they
must be
clearly visible
now
as
Intermissions
In
the
pattern.
After
you have checked
the
display,
press
the
upper
select/adjust
key once.
Now
an
oscilloscope
screen
is
displayed.
Figure 4.2
Test pattern
Press the
upper
select/adjust
key again
to
go
to
step
2.
Now
the display
shows
the
same
pattern, but with
a low
contrast
(bright
screen).
This
will
help
you
to
locate
any
failures
in
the pixel
rows
of
the
LCD.
3.
Ground
level
check
P
ress
th
e
u
pper se
lect/adj u st
key
to
go
to
step
3.
The
purpose
of this
step
is
to
check
the
ground
level
position ddjusiments
(OV)
for
both
traces.
The
ScopeMeter
display
shows
th©
text
"
Verif
3",
to
show
that this
is
the
third
SCOPE
Performance
Verif icatron step (see
figure
4.3).
Requirements:
A tOOmV
OND
B tOOfnV
QNO
lOOus/OV
Trig:
A/
a
r
Ag
1
1
ser' VICE
1
—
Verity
CALIBRATE
S
METER
EiU
ScopeMeter
EXrT
Figure 4.3 Reference set-up
Venfy
thal
the traces of both
channels
A
and B
are situated on
the
vertical
middle
of
the screen.