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Step
Item/Component
Required Condition
Remarks
1
Check
chopper
amplifier
operation
per
Table
5-7,
steps
1
thru
10.
2
Select
2kQ
range.
Short
Input,
3
Display
.0000
±
1
digit.
4
TP9*
-IV Approximately
Inverted reference voltage
plus calibrated offset of
U107.
5
INPUT
HI to
LO
Remove
short
and
connect
ammeter
If
incorrect,
check
R158
and
from
INPUT
HI to
LO.
Source
switching
to
INPUT
HI
and
current
should be approximately
1mA,
HI terminal negative.
chopper
amplifier.
6
INPUT
Hi to
LO
Remove
ammeter
and measure open
HI
negative with respect
to
circuit
voltage.
Voltage
must
be
LO.
Display
should
be
blink-
-2
to -5V.
ing, indicating
overrange.
7
1
.9kQ
resistor.
Apply
to
INPUT.
Calibrated
resistance.
8
Display
1.9000
+
12
digits.
Subtract
test
lead resistance
from
reading.
Checks
accuracy
of
R158 and
feed-
back
loop
to
U107.
9
19kfi
resistor.
Apply
to
INPUT.
Select
20kQ
range.
Calibrated
resistance.
10
Display
19.000
±
12
digits.
Source
resistors:
R158,
R154
|8.975kQ),
R157
(wiper).
11
190kii
resistor.
Apply
to
INPUT.
Select 200kSi range.
Calibrated
resistance.
12
Display
190.00
±
12
digits.
Source
resistors;
R158,
R157
R156
(wiper),
R154
(89.75kfi,
8.975kf2).
13
ISOOkO
resistor.
Apply
to
INPUT.
Select
2000kfi range.
Calibrated
resistance.
14
Display
1900.0
±12
digits.
Source
resistors:
R158, R157,
R156,
R155
(wiper),
R154,
(all
except 8.975MQ).
15
10MO
resistor.
Apply
to
INPUT.
Select
20MQ
range.
Calibrated
resistance.
16
Display
10.000
±12
digits.
Source
resistors:
all
range
resistors.
NOTE: To
con-
veniently
measure
the
resis-
NOTE:
Reference
loading
by
the
tance
of
all
Q
range
resistors.
ohms
source does
not
affect
0
turn
power
off,
set
all
readout
since
A/D
converter
is
function switches out
and
ratiometric.
measure
resistance
INPUT
HI
to
LO.
*See
Figure
5-1.
Table
5-10.
Current
Shunt Checks
Step
item/Component
Required Condition
Remarks
1
F101
Continuity
2
R101, R102, R103,
Correct
shunt
value
Apply
a
known
Vi
scale
3
R104,
R105
for specified
range.
See
schematic.
Turn
power
on. Select
DCA
and
200;uA
range.
current
and measure
voltage across shunt.
4
External
voltage
source.
0
to
3V.
Clamping
must
occur
at
±2V.
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