Fluke 8600A - A;Dconverter Control

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
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