Fluke 8012A - 4-54. RMS Converter DC Offset Adjustment; 4-56. AC Calibration Adjustment; 4-58. LO RANGE Ω Calibration Adjustment (8012 A Only)

MAINTENANCE
CALIBRATION PROCEDURE
4.
On
the UUT, adjust R4 (DC CAL)
for
a
display
reading of exactly
“1.888”.
5. Reverse
the
input
leads (V/kH/S and
COMMON)
on the
UUT.
Verify that
the
display
reading is
between
“-1.887”
and
“-1.889”.
6. If necessary, adjust
R4
until the readings
of
Step
4 and 5 are within 1
digit
of 1.888V.
4-54. RMS Converter DC Offset
Adjustment
4-55.
Use
the following procedure to adjust
the
dc offset
of
the rms
converter:
1.
On
the UUT, select the AC
V function,
any
range.
2.
Connect the Low Ohms
Calibration
Lead
between the
V/kO/S and
COMMON input
terminals.
3.
Measure and record
the voltage level on
TPl
using
the DMM. Verify
that
the level at
TPl is
between
-20
mV
and
20
mV.
4.
Connect the DMM
to
TP2.
5.
Adjust R7 on
the
rms
hybrid network
so
that
the voltage
level
on
TP2 is
within 0.5 mV of the
level recorded on TPl.
4-56.
AC
Calibration Adjustment
4-57.
There are four
interacting adjustments
in this
procedure. Two
potentiometers
set the low
and
high
levels at
low
frequencies, and two variable capacitors set
the high levels at high
frequency. Use
the
following
procedure to
calibrate AC Voltage and AC Current
functions:
1. On
the UUT, select AC
V, 2V
range.
2. Set the DMM
Calibrator
for an
output
of
1.900V
at a
frequency of
100
Hz.
3.
Connect the HI output ofthe DMM Calibrator
to the V/kfl/ S input of the UUT.
Connect
the
LO
output
of
the DMM Calibrator to the
COMMON input of the
UUT.
4. Adjust R19 (AC
HI)
for a
display reading
of
exactly
“1.900”.
5.
Set the DMM Calibrator for an output of
190.0
mV at
100
Hz.
6.
Adjust R21 (AC LO) for a
display reading
of
exactly
“.190”.
7.
The
adjustments of R19 and R21 interact.
Repeat
steps
1
through
6 of
this
procedure until
both
readings are within
1
count
of
the
designated
values.
8.
On
the UUT,
select the 20V range.
9. Set
the DMM Calibrator for
an
output of
19.00V at a
frequency
of 10
kHz.
10.
Adjust Cl for
a
display
reading
of
exactly
“19.00”.
11.
On
the UUT,
select
the 200V
range.
12.
Set
the
DMM Calibrator for an output of
IIO.OV
at a frequency of 10 kHz.
13.
Adjust
C4
for a display reading of exactly
“
110
.
0
”.
14. If
any
adjustments were made in this
procedure, repeat Steps 1 through 13.
4-58. LO
RANGE
O
Calibration Adjustment (8012A
Only)
4-59.
Use
the following
procedure
to
calibrate the
circuits of
the LO RANGE O
function:
1.
On
the UUT,
select
the
LO RANGE O
function,
20fl range.
2. On
the UUT, connect the Low Ohms
Calibration
Lead between the COMMON and
LO
RANGE fl input terminals.
3.
Adjust the front panel ZERO
control
until
the
display
reading
is
all
zeros.
4.
Remove
the Low Ohms Calibration Lead from
the
COMMON
terminal, plug the
1
9fl Test Set
into the COMMON
terminal and plug the
Low
Ohms
Calibration Lead into the 19fl Test Set.
5.
Adjust R57 for
an
display reading
of
exactly
“19.00”.
6.
Replace
the 19fl Test Set with the 1.9fl Test
Set.
7.
On
the UUT,
select
the
2fl range.
8.
Verify
that
the display reading
is between
“1.879”
and
“1.921”.
4-9