51
SECTION
4
INTERNAL
ADJUSTMENT
PROCEDURES
4.1
ALTERATtON
OF LINE
VOLTAGE
AND
LINE
FREQUENCY
The instrument is set to
50Hz, 205V to 255V
supplies
unless Option
80,
81
or 82 is
specified.
This
information is
carried
on
the
instrument
identification
label located on
the
rear
panel. Alteration to a
different
line voltage/line frequency
may
necessitate
an
instrument
recalibration.
4.1.1
Changing Line
Voltage
1.
Disconnect
power
and all signal
input/output
leads.
2.
Remove
the
lower
cover.
3.
Locate the
link(s) connecting
the
split primary
on
the prirrted
circuit board
in front of the
toroidal
line transformer.
Fig. 2.1
and Drawing No 400295.
4.
115V
Operation:—
Remove
LK1
(link
Hand
fit
LK2
and
LK3‘
‘
.
230V
Operation;— Remove
links LK2
and
LK3,
and
fit
LKl(’).
5.
Amend instrument
identification
label.
6. Replace
lower cover.
7.
Replace
power
fuses with 160mA
anti-surge (230V)
or 500mA
anti-surge
(115V).
8.
Carry out
the
Specification Verification tests (Sec-
tion
8,
User's Handbook)
and
recalibrate if
necessary.
4.1.2
Changing
Line
Frequency
1.
Disconnect power and
all signal input/output leads.
2.
Remove the top
cover.
3.
400Hz
Operation:—
Remove
link
LK5 and
fit
LK?f^J
on
the Digital
assembly,
(Drawing No.
400329).
50/60HZ Operation:-- remove
link
LK7
and fit
LKSt^^
on the Digital assembly
(Drawing
No.
400329).
4.
Place instrument into HOLD. Adjust L2
(Digital
assembly) so that TP7 is 1.05V ±0.03V
with respect
to Digital
Common
(TP28).
NOTE:
This signal contains about 200mV peak-to-peak
high frequency noise.
5.
Amend instrument
identification label.
6. Replace the top
cover.
7. Carry out the
Specification
Verification
tests (Sec-
tion
8,
User's
Handbook) and
recalibrate
if necessary.
Links should
be 22
SWG
TIN.Cu wire with silicone
rubber sleeving.
4.2
BATTERY
REPLACEMENT
The
battery
should
be
replaced on
or
before the
date
indicated
on the
rear
panel
instrument
identification
label. To
retain the
calibration
memory,
the
instrument
must be
powered-up
during
replacement.
Therefore
great
care must
be
taken due
to
voltages
up to
260
volts
being
present
inside the
instrument.
1. Remove top
cover and
locate battery
on
the
Digital
assembly (see
Fig. 2.1 ).
2.
Power-up
instrument.
3.
Desolder
battery
at end
of tags
and
remove from clip.
4.
Replace with
new
battery, (Datron
Part No.
920049)
positive
terminal to
resistor.
5.
Replace top
cover.
6.
Amend instrument
identification
label (Current
date
-t-
5
years).
7.
Carry out
the
Specification
Verification tests
(Sec-
tion
8,
User's
Handbook)
and
recalibrate
if
necessary.
4.3
POST-REPAIR
PROCEDURES
Apart
from the RMS
Module
(which
is available
only
from
Datron),
all
integrated
circuits
and
semiconductor
devices
are
standard
manufacturers'
products,
and
special
selection
is
unnecessary.
During
manufacture
certain
resistors
are
selected
in
value (FSV
=
Factory
Selected
Value)
to
accommodate
circuit
component
tolerances, or
to
bring the
desired
setting
of a
preset
control to
the
middle of its
adjustment
range.
The
thermal
tracking
of the DC
Preamplifier
is part-
icularly
important, to
ensure a
low order
of zero drift
with
variations
of
temperature.
This rather time
consum-
ing
procedure
is
carried out
initially
during
manufacture,
and
need
only be
repeated
following
replacement
of
Q12
or any
component
associated
with the
temperature com-
pensation
circuitry.
NOTE:
A
routine
calibration
as
detailed in Section
1
should
be
carried out
after
completion
of
the
following
procedures.
CAUTION
:
Up
to 260
volts
is present inside the
instrument.
Personal
contact
with these
points
may
result
in injury.
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