A/Dconverter Control - Fluke 8600A Instruction Manual

8600A
RANDOM
NOISE
COMPARE
OUTPUT
TP6
-
Q14
Gate
026
Gate
-
021
Gate
-
INTEGRATOR
OUTPUT
—
INTEGRATOR
CONTROL
—
DE
(+RI
CONTROL
—
DEI—
R)
CONTROL
"
AUTOZERO
—
CONTROL
-f o
<s>
NEGATIVE INPUT
-2.2V
POSITIVE
INPUT
-2.2V
»''•*
<
in'
100ms
Constant
Variable
Dependent
I
on Input
|
Overload
at
200ms
100ms
Constant
Variable
Dependent
on Input
10
/Us
per
digit)
Figure 4-4.
A/D
CONVERTER CONTROL SIGNALS
b.
Apply
OV
dc to
TP2 by
connecting
it
to
TP3
(ground). Refer to
table 4-1
1
for
test
points
and
indications.
c.
Apply
+5V
dc to
TP2
by connecting
it
to
TP
12
(+5V
supply).
Refer to table 4-1
1
for
test
points
and
indications.
4-61.
The operation of the range control system can be
checked by
observing the interaction
of U8, U9, U16, and
the
function switches.
For switching between the lowest
range and the higher
ranges,
U17
changes
the reference
applied to
U4
and
the charge
path of C28. Table 4-12
contains truth tables for
U8
and U9.
It
also
shows which
relays are
energized
in
each
range
and the internal switching
arrangements
for
U16
and U17.
To
check
a
questionable
range,
select
the range
manually and check
the inputs
and
outputs given
in
Table 4-12
that affect that range.
Keep
in
mind
that relay
common
is
+5V
so
in
all
cases
the output
of
U9
goes low
to select a relay.
The
strobe signals are
used
to
program
U8
for the different ranges.
U16
together
with
the
range switches apply the
ST
signals to
U8
as
explained
in
Theory
of Operation.
TP2 INPUT
FRONT PANEL
DISPLAY
AZ
U8 PIN
2
INT
U8 PIN 40
DE{+R)
U8 PIN 38
DEI—
R)
U8 PIN 39
OV
dc
OVERRANGE
PULSE
PULSE
OV
dc
PULSE
+5V
dc
OVERRANGE
PULSE
PULSE PULSE
OV
dc
PULSE
AMPLITUDE SHOULD
BE 15V
(FROM
OV
dc
to-
15V
dc)
Table 4-1
1
OPERATION OF
U8
WITH RESPECT TO A/D
CONVERTER
4-10
1/77